Is is safe and ok to use low pressure 2 3/4" 12 gauge shells in a nitro proofed gun with 2 1/2" Chambers? If so, what would be the recommended pressure to stay under? Thanks!

Steve, absolutley not. Use only 2 1/2" shells and low pressure because that is what that gun was made for when proofed. Others will say it is ok, but the 2 3/4" shell won't open fully causing a lot of extra pressure.
I would stay to around 8,000 psi.

Please see this thread
http://www.16ga.com/forum/viewtopic.php?t=1983

If you need low pressure 2 1/2" cartridges for an older gun, contact Polywad or RST.

http://www.polywad-shotgun-shells.com/

Just noticed that WLM is now offering 2.5" low-pressure shells for 12 & 16 ga. as well. Website is http://www.williamlarkinmoore.com/product_details.asp?id=1443

Here's what they're offering:

Shotgun & Shooting Accessories, Ammunition, 12 GA & 16GA, 2 1/2, 1180 fps velocity& 7000 psi max pressure, extra hard shot, 1 pc plastic wad, Specially developed and loaded exclusively for us by Thunderbird Cartridge Co. Designed for older guns with 2 1 /2" chambers. For use only in sound, quality guns originally built with 2 1/2" or longer chambers and using smokeless ammuntion. Case price $80.00 per flat of 10 boxes. $9

JMC: I shoot the WLM 7/8 oz 2 1/2" 16s regularly. The 16s are only available in 8s. Thunderbird is a local outfit and they use Fiocchi cases. Quality loads similar to RST or Polywad.

It is not that simple and Sherman Bells articles in DGJ have shown that it MAY be ok. The ' a lot extra pressure' has not been documented in Bells articles in which a pressure gun was used.

Also the fact that many historic makers often 'short chambered' their guns.

You will also find that many 2 1/2" shells are actually 67.5mm long and standard 2 1/2" chamber is actually 65mm long.

I am not trying to be contrary but the answer is not as simple as JDW has made it seem.

I have a 2 9/16" singleshot Iver Johnson that replicates the chambers in two damascus sxs guns. I also have a Pressure Trace piezio transducer pressure measurment instrument and a chronograph. The Iver is instrumented and serves as my test gun for pressure testing.

After reading Sherman Bell's article where a true 2 1/2", short forcing cone, chamber was used to test 2 3/4" shells, I went forward with the knowledge that he got a maximum of about 15% increase in pressure after testing a variety of loads, and some had no increased pressure. The average increase in pressure seemed to be about 10%.

I shoot full 2 3/4" paper Fed shells loaded to generate about 6500 psi in the short chambers. The loading manual I have suggests this load should generate around 7000 psi. That loading manual refers to a 2 3/4" chamber pressure gun.

I've shot hundreds of these loads thru my damascus guns. When in doubt, get real data. Everything else is heresay. If someone has direct knowledge that this is an unsafe practice to shoot 2 3/4" shells in a 2 1/2 -2 9/16" chamber, please share.

The American and British "system" of shotshell lengths is confussing. There are 2,0, 2 1/4, (2 3/8?), 2 1/2, 2 9/16, 2 5/8, 2 3/4, 2 7/8. It is so much simpler with just 65, 67, 70 mm.

Then add actual chamber lenghts -- it is widely reported that USA makers once found that 1/8 inch shorter chambers than fired hulls gave tighter patters. Then add the modern tendency to increace forcing cone lengths in old guns from those essential with card and fiber wads.

Most of my old doubles have 65 or 67 mm chambers and short forcing cones. I shoot 65 and 67 mm ammo in them rather interchangably, as "allowed" by CIP regs. I DO NOT shoot American-made ammo with actual 70 mm hulls and near SAAMI chamber pressures in any of them.

I don't even shoot low pressure handloads in true 70 mm hulls in any of the 65 mm chambers. Reason? More recoil, which can only be higher velocity, which can only be result of increased chamber pressure, which can only be because of additional 5,0 mm of hull in short forcing cone. I do not find this with 65 vs 67 mm hulls.

Some shooters get the short (about 1.0 cm) forcing cones lenghtened to 3-4 cm. They claim it lets them safely shoot 70 mm hulled ammo in these guns, without lengthening the chambers.

Take any simple statements about chamber vs fired hull lenght with ample salt, including Tom Bells qualified statement.

Niklas

The Winter 2001 Double Gun Journal has the article by Sherman Bell called "Finding Out for Myself" Part V "Long Shells in Short Chambers".

After extensive testing carried out in a very professional manner he concludes:

"With loads that are sensible in a light 2 1/2 inch gun, we see no dangerous pressure levels produced. I see no reason, related to safety, to modify an original 2 1/2 inch chambered gun to shoot 2 3/4 shells, If The 2 3/4 Inch Load You Intend To Use Would Develop Pressure That Is Safe In That Gun, When Fired In A Standard Chamber!

I personally perceive slightly greater recoil with my 2 9/16" chambered 16g LC than with my 2 3/4" chambered 16g LC using the same 2 1/2" shells, and for that reason the brls are with Dan Lammers getting the chambers lengthened right now.

Steve

I will not tell anyone that it's safe to shoot longer 2 3/4" ammo in a 2 1/2" gun. I will however tell you that I reload to below 7000 psi in the longer hulls and shoot them in my 2 1/2" light game gun. I have been watching several boards for about 5 years and I have never heard of any problems with this practice. If you are concerned just buy the factory ammo for the peace of mind. That has to be worth something.

Jim

Jims advice is good. You have to do what makes you comfortable.

Some folks will shoot damascus guns, some won't. The same advice applies.

It is absolutely not the same choice as shooting damascus guns or not shooting them. A damascus barreled gun proofed for use with 70mm loads is as safe as a steel barrel proofed for the same - it has been 'prooved' to be so. Shooting an out of proof steel gun or an out of proof damascus gun is equaliiy stupid and risky.

This is especially true of old British guns, that were constructed carefully to certain dimensions and tolearances according to the job they were required to do.

Anybody putting 70mm ammunition in a 2 1/2" proof stamped shotgun is a fool in my opinion. Anybody advising others that it is a safe practice is irresponsible to put it mildly.

Some people feel comfortable doing 100mph on an old motorbike without a helmet - that doesn't make it safe or sensible!

British guns are proofed to withstand regular use with the ammunition designed for use in them (that is the point of the various proof options; otherwise everything would have been built to weigh 8lbs, given a 3" chamber and 4 tons per square inch proof).

Why is it so difficult to understand that if you use the wrong ammo, it will eventually damage the gun and is potentially dangerous?

Perhaps it is dumb thinking like this that has led Beretta et al to put 3" magnum steel shot proofed barrels on even their light 20-bores today - because the shooting public can no longer be bothered to follow the simple instructions given about selecting the correct load for their guns.

If you are going to shoot old shotguns, understand what they were built for and load them with the right ammo. I can see no excuse for putting a 70mm shell in a 2 1/2" chamberd gun.

Then I'm a fool. Sometimes I use light 2 3/4 case loads in 2 1/2 chamber English guns, because UK chamber dimentions standarts are not so tight as German ones for example. Also it depends on forcing cone length and bore gauge. 12G, 13/1 and 13G are o'key in this case.
I feel I'm pretty much educated to check guns and to choose right ammo for these guns. Sometimes 2 1/2" case doesn't mean at all it could be used in 2 1/2" chambers.
Who says use ONLY 2 1/2 ammo in 2 1/2 chambers probably a fool, because ammo has to be proper to particular gun in many aspects and not only in case legnth.

Gough Thomas must have been a fool as well as 20 years before Sherman Bells' article, he intimated in "Shotguns and Cartridges for Game and Clays" that proper pressure 2 3/4" shells were ok in 2 1/2" chambered guns.
I have never had any problem using plastic 2 3/4" low pressure reloads in such guns.
That being said, RST makes 2 1/2" 12 gauge shells that are milder and burn cleaner than I can duplicate and they deserve your business.

Here is what I have in mind. A 12 ga reload using Remington hull, Rem 209P primer, PurplePC wad, 16.7 grains of Clays, 1 oz shot. This load produces 1125 FPS @ 6100 psi. (Data from Hodgdon Manual, 2002) The gun that this will be used in is a Wm Lee (circa 1890) SLNE with nitro proofed barrels. For very ocasional use, mostly at vintage events and skeet.

I plan on evenutally using a similar PSI load in my 16's as found in the data from that I received from the 16 ga reloader's organization.

I have a case of Westley Richards, Classic Game Load 2 1/2" (65mm) Shells. After using a couple of boxes, I feel uncomfortable using them in this gun because there is no pressure data (that I could find)

I would appreciate any and all feedback.

PS: I went back over my DGJ's and found Sherman Bell's article.

Since I am a fool, I wouldn't hesitate.
I see this load as a very sensible choice.
My personal 12 gauge load for 2 1/2" brit doubles
consists of 24 grains of SR 7625 in a Win AA or Rem STS case, win 209 primer and Win AA or Claybuster wad.
I don't recall the exact ballistics as I have been using this load successfully for ten years. It ias right out of the old IMR booklet. It is a bit dirty as most slow burning powders are. Using less than one ounce of shot with this powder produced duds for me.

"It is extremely dangerous to shoot 2 3/4-inch hulls in a gun chambered for 2 1/2-inch cartridges. The reasons against such a practice cannot be stressed enough."

"First of all, the cartridge itself is too long to fit into the chamber properly, the end result being that the front end of the hull is forced into the chamber cone. This will cause serious rise in pressure, a dangerous factor in itself."

Beyond that, powder and shot charges in 2 3/4-inch cartridges are usually heavier than those used in 2 1/2-inch shells, for which your gun has been proofed. By combining these two factors, you run the risk of building up a higher pressure than your shotgun can withstand, thereby increasing your chances of an accident."

"To be on the safe side, stick with 2 1/2-inch cartridges."...

From the editor of SHOOTING SPORTSMAN magazine Feb/March 1988 page 89.

"Sherman Bells articles in DGJ have shown that it MAY be ok."

May is still not definitive.
I'm still having a hard time believing that most of the educated people here talk about gun safety and do this. First of all WHY would you want to do it. There are loads out there made for 2 1/2" chambers, why take a chance on ruining a great old gun and possibly hurting yourself or a bystander.
It's the same as saying I can shoot 3" shells out of my 2 3/4" proofed modern gun. It will fit right into a 2 3/4" chamber why not use it, and it's only figurativly a 1/4" longer.
Those of you that have done it and are still doing it, bless you, though I won't be doing so and I hope that all goes well for you. I hope there will be no pictures posted of blown barrels like the gentleman who shot bizmuth through his old gun.

Small Bore has hit the subject square on the head in his statement.

I fully understand the prudent concern on this subject. And I also fully understand the very real danger of someone reading this thread and only walking away with overly simplistic mantra of "it is now OK to shoot long shells in short chambers" because I read it on the DGJ BBS.

That all said, the issue is pressue - specifically the impact to pressure due to the slighlty longer shells in shorter chambers.

Bell, Burrard, and others have shown that while there undoubtably IS an increase in chamber pressure with slightly longer shells, that the pressure increase is not huge - nominally about 15%. If that additional 15% increase in pressure pushes the total pressure above the working pressures the gun was designed to operate in, then I agree you have a problem. If that pressure is still well below the safe threshold, then you are within the pressures that the gun was designed to handle.

I agree with several posters that it is pretty easy to obtain 2.5" shells that are loaded to lower pressures. So there is no pressing need to do this. Still, it makes me uncomfortable to hear the overly simplistic cries of "extreme danger" when the people who have obviously read up on the issues and taken the time to think hard about the subject are characterized as some type of looneys for doing so. Reminds me of the "damanscus" threads on other boards.

Geno is also right. Just because you are shooting 2.75" shells in 2.75" chambers (or 2.5" shells in 2.5" chambers) is no guarantee in of itself of safety in older guns. The issue is pressure. And of course the biggest problem here is that MOST commercial 2.75" shells are loaded to higher pressures than 2.5" shells. So it is not an apples to apples comparison from the start.


We have thrashed out this topic on the board before. For the vast majority who do not want to work through the intricacies of the pressure issues on their particulr gun, then it is best to stick with the low pressure 2.5 shells in 2.5 chambers. It just irks me to be characterized as doing something dangerous from some have not read in depth on the topic. It reminds me of the time a fellow "expert" shooter about yanked the double out of my hands on the range because he saw it to be a nice damascus double.

Ken

This question has been debated ad nauseum on this and other Forums. What is often cited as Gospal is Sherman Bell's writings in the DGJ. As a Degreed Engineer with Graduate study and research in Metalurgy, I have found Bell's articles to be superficial in content and approach as well as potentially dangerous for others to use his results to justify thier use of shells for which a shotgun was not chambered. When an item is manufactured, it is engineered for a specific set of requirements. To change those requirements is folly when dealing with shotgun chambers. I will not debate this again but simply note that there is at least one person with academic credentials that does not agree with Bell. EOT-Dick

I didn't mention proof or any other technical issues in my post. I was referring to CHOICES that folks make.

It is about pressure, pressure & pressure.

Dick it is spelled 'gospel'.

All I can suggest is the you read Sherman Bells articles and anything else you can get your hands on. The naysayers will always yell loudest. Gather information and make a decision for yourself.

'May' was my word to condense thousands of words on dozens of pages in his articles.

Why not use 3" shells in a 2 3/4" gun. Because there is not a single 3" shell ever produced that is LOW PRESSURE. Many fine British, Spanish and other guns have 2 3/4" chambers but are still designed for LOW PRESSURE.

Dude, bizmuth(sic) was designed for older guns that can not handle STEEL shot.

Last comment for the moment on this thread.

This has been studied forever. I have an American Rifleman article from the 1930's concerning shotshell pressures and chamber length (among other items) as they were setting up SAAMI.

No one has mentioned cost. 2 1/2" shells are not common on the shelves of American gunshops. Having them delivered to your home is prohibitively expensive for many of us. Particularly when we have already stretched the budget to its breaking point to buy a fine older gun.

In fact loading LOW PRESSURE shotshells is one of the few areas of reloading whre you can still save signifigant money.

Of course you can (and I have) trim hulls to 2 1/2" but this adds time, cost and complexity which can quickly make the process not worth the effort.

I recently got my first English sxs, a hundred year old 2 1/2". Spent the first 60 years of my life KNOWING you can't shoot 3" in a 2 3/4" gun, etc. I researched the topic for a couple months. Gogh Thomas and Sherman Bell both say, with proper pressure loads, you may be o.k. That said, I'm reloading and buying 2 1/2" for my gun. First reason, it is fun to have something new and totally different, second reason it seems prudent to me.

That said, there is a portion of this topic I've never seen addressed. Does anyone know, if you do shoot 2 3/4" in a 2 1/2" gun, does it affect patterning? Any additional pressure would be generated by forcing the payload into a more restricted area. My flawed logic tells me that would deform shot, and possibly cause the pellets to "bounce" through the forcing cone.

Steve

OK, How low a pressure would be considered low enough? The load I have in mind to use will produce no more than 6700 PSI. Not to mention that I doubt that I will shoot more than 250 rounds per year in this gun.

I try to stay below about 8000 psi service pressure. This is slightly below what the gun was originally proofed for as a service pressure.
The former owner of my gun, shot boxes and boxes of modern field loads that were most likely loaded to about 11,000 psi with no ill effect.
If upon firing your handloads, you find that the ends of your cases are getting torn and shredded, then I would say that you might want to stick with 2 1/2" cases.
Just to save on cases! Thin walled hulls like the old style AAs are probably least likely to give you trouble.
I am speaking from ten years of my own experience with nitro proofed guns in good condition. I have read all the books and have made my choice with the particular guns that I use.
It really is up to you to decide.

FYI to Steve and anyone else loading for 16X65s or 16X67s,

ALL the recent 16 gauge Remington (black hulls) and Fiocchi marked hulls I have are actually 67 mm, even though marked 70 mm. These hulls I use unaltered for reloads to be used in 65 and 67 mm chambers. All my old doubles are Husqvarnas (actual 65 mm chambers) or German-made (actual 67 mm chambers), nearly all with the unaltered, nice tight chambers and bores common to such guns. 24 gram (7/8 oz) and 28 gram loads at 1100-1200 fps in 67 mm hulls perform really well in these guns -- as they should, those are the loads these guns were designed for. Ditto for some lightweight Husqvarna and German 12X65-chambered hammer doubles.

Elsewhere on this Board are data giving chamber pressures for the Remington and Fiocchi 16 gauge shotshells. I know that the factory Remington shotshells with 28 grams shot and actual 67 mm hulls have chamber pressures well above 10.000 psi, but, think I recall that the chamber pressures of the Fiocchi 28 gram loads are well below that.

Niklas

Mike,

But Dick has technical degrees for godsake . . . from a University no less!

Dick,

For the record there are several other people with technical degrees on this board who do agree with Bell's work - within the carefully delineated limits of his testing. Please note the many caveats that are used by him throughout his articles.

Until more extensive empirical experiments are conducted on damascus barrels by you or anyone else, I'll stick with Bell (and the host of others, including the proof houses, that agree with him.)

I'm out on this thread. I don't mean to be rude in my response, but admit to responding to what I perceived as "I have an engineering degree and Bell doesn't, therefore, I am the only one capable of understanding this."

Ken

"Dude, bizmuth(sic) was designed for older guns that can not handle STEEL shot"

From the 16 ga Reloaders Group

"Okay, I'm going to step in here. I used to use a 1918 Field Grade L.C. Smith 12ga. to shoot trap with. I shot several thousand handload and factory load target shells AA's, STS's, etc. and never had a problem. Then I used the gun for goose with factory loaded 2 3/4 in. bismuth loads. I learned a lesson the hard way. Just because a shell fits the gun does not mean it is safe to use." Take it from Nine Fingered Mark.
This is from the gentleman who posted a picture of the gun with the blown barrel.

Again this is a gun that isn't proofed from Hunter Arms in 1918, proof didn't start until around 20's.

So what you are saying Mike is that it is ok to shoot bizmuth in "old guns not made for steel". You better define "OLD" dude!

Cobbhead,

In the one case where I did use 70 mm hulled, American-loaded shotshells in old gun with 65 mm chambers and cm-long forcing cones (I was lied to by person I bought gun from, and did not check chamber lenght) I got frayed ends of hulls and worse patterns and much greater recoil. I then cut hulls to 65 mm and used hartin crimps, which resulted in much tighter patterns and much less recoil.

In contrast, I have gotten slightly better (tighter, more even distribution) patterns when the tappered end of plastic hull extended about one half way into short (cm-length) forcing cones. Probably same effect as found by USA ammo companies in 1920-1940s with card and fiber wads. The ends of these hulls did not fray, like the ends of 70 mm hulls in 65 mm chambers. Would presume that the 50% protrusion of hull into short forcing cone simply reduces the extent of the discontinuity that shot and wads must traverse.

Niklas

JDW,

Given its softness, Bismuth shot is DESIGNED as a safe, non-toxic lead alternative for older guns. I regulalry shoot LOW-PRESSUE bismuth loads in many "older" guns (1875 - 1915).


PRESSURE is what blew this gun up. He should not have been shooting modern high-pressure loads in an old gun period - with lead or bismuth.

Ken

Ken, you are correct, and when I originally posted said statement, and being a reloader myself, I was refering to that gentleman who had shot thousands of reloads and factory rounds out of an old gun before proof. It is like he stated "just because a shell fits a gun does not mean it is safe to use" That has been my whole point right along, I just referred readers to that one particular case to make a point.
So when someone comes on the board saying that bizmuth was made for older guns that cannot handle steel and not being specific, then I have a problem with that.
Like I said I won't be shooting shells not designed for my old guns and definetly not longer shells in a shorter chamber.

I've heard a lot of opinions in this thread. Some opinions, by proponents of 2 3/4" shells in shorter chambers, are based on Bell's work and extrapolated to their reloads. While Bell provided some informative data, unless I were using the exact loads he tested, I'd be uncomfortable.

I think Bell simply cracked the door open for a promising outcome of those wishing to further pursue testing of their selected long shell/short chamber load.

I realize that there is a vast diversity of knowledge/education/experience here on this bbs, but have yet to hear that anyone has pressure data that indicates the subject practice is unsafe. I work with hundreds of engineers and often represent many of them in front of our regulatory agencies. They are all educated and knowledgeable people...in their respective fields and within their education and experience. I challenge them all the time, because they can't know everything, they are people and put on their trouser's one leg at a time like everyone else...they can err.

Sure, cramming a WallyWorld modern 2 3/4 load into a shortchambered 100 yr old gun is potentially unsafe and without a doubt foolish.

I have explained my approach to obtain direct data on this in my first post on page 1 of this thread. I think those that are pursueing the loading of long shells for short chambers should obtain pressure data of their particular load in the chamber dimensions they will be using. It's not a huge investment.

So, I'll say it another way; If someone has direct knowledge that this is an unsafe practice to shoot 2 3/4" shells in a 2 1/2 -2 9/16" chamber, please share. To me, this means actual pressure data. If any of our membership out there has real pressure data to share, I think it would truly be a service to our community.

JDW,

I am not picking a fight. I have been a member of the 16ga group since its inception and saw the pictures. Someday I'll actually own one.

I didn't type in a pressure reference to the bismuth because as you might notice, I had addressed pressure immediately above.



In fact in my posts I have been typing PRESSURE in all caps to reinforce that point.

Old is well old. Since I gave my 11-87 to my son my newest shotgun was made in 1933. My regular waterfowling guns are damascus barreled W&C Scott hammerguns. 10ga made 1875ish and a 12ga made 1880ish. Both used with nitro and blackpowder loads shooting bismuth.

I followed the load in the published manual using Clays, 1 oz. and windjammers for a 5500 psi load cutting down my Rem hulls to 2 1/2". I shot about 500 of them but somethng was telling me it wasn't right. I had Tom Armbrust test them and they came in at around 7500 psi. They were also a pain to make. The Harten crimp requires an overshot card which halves the output from either my RCBS Grand or MEC9000. I therefore used a load that is much more popular and well know using PB which comes in around 5200 psi and further made the decision to eliminate the harten crimp and use 2 3/4" Rem hulls figuring the loads would come in at 6000 psi. I have no proof that my assumptions are correct though. I also decided to go with gun club hulls instead of STS since they were more flexible and thinner.

It was fun to watch the confetti come out of the barrels when shooting with the overshot cards. For some unknown reason, I also found that the cut down 2 1/2" hulls took a bit of a beating and were covered in black- much like a 28gauge Rem reload after several uses.

I shoot with a lot of guys from the Vintagers and although I don't think it is wise (and I don't do it) many shoot 2 3/4 dram Rem STS loads in their Parkers and other stout guns, both steel and damascus barrels, and so far there does not seem to be any problems. A lot of these guys are serious shooters and we are talking a lot of rounds per year. I guess they are looking at the thickness of the chambers and barrels and deciding nothing will hurt them.

I, on the other hand, am a chicken and hate hospitals so I will stick with my low pressure loads. I should have Tom test the ones I make and extrapolate the increase of pressure from the short chambers. I do feel comfortable with the info in the finding out for myself article. I will let you all know if I have a problem.

Best,
Ten finger Milt(so far)

Are the factory Bismuth 'Sporting Game' loads considered low pressure? The Cabela's site quotes "Safe for use in standard lead chokes and nitro-proofed barrels." but I take this as a attribute of the softness of the shot, not pressure.. Am I wrong?

thanks,
jmc

I think there have been some posts on this BBS concerning this. Many historic American makers 'short chambered' their guns to get a better seal as the crimp openend into the 'short chamber/forcing cone' area. This was intended as I remember for paper hulls and fiber wads but you might be getting some 'blowback' if your shorter hulls are not getting a complete seal at the junction of the chamber and forcing cone.

From the Parker Gun Collectors Forum:
http://www.parkergun.org/forums/forum1/2164.html

Parker "borrowed" English chamber measurements (for paper shells) and manufactured 12ga and 16 ga 2 1/2" chambers until about 1895...then the 12 ga went to and continued with 2 5/8"chambers (16ga went mostly to 2 9/16" ) for a long period...possibly until near the end of regular Parker production...about 1934. By 1930 most (but not all) shotshell and gun manufacturers agreed to 2 3/4" chambers for field and target guns. As far as I can determine, 2 5/8" shells were manufactured at least until 1940. The 1945 Stoegers Shooters Bible lists Xpert and Xpert Super Skeet loads, Ranger Field loads, and Leader Staynless loads as being available in 2 5/8" 1 1/8oz. By that time all Super-X, Super Speed, Leader Super Speed, Ranger Brush Loads, etc were 2 3/4" 1 1/4oz. Original chamber length is a strong clue as to the correct MAXIMUM shot load.

I don't know what to make of the 1920 "2 1/2" Standard Shotgun Chambers drawing" (p519 TPS). Some information is obviously missing. In original 12ga chambered guns (frame size #2 and smaller), a 12ga .798 chamber gauge will stop most commonly at either 2 5/8" or 2 3/4". Why does a .798 gauge not stop at 2 1/2" as depicted in the drawing? The difference due to chamber taper is of course, negligible, but why would Parker make a "shop drawing" and not use it? Why was this 2 1/2 inch "standard" adopted in 1920 when Trap Guns were standardized at 2 3/4 inch chambers much earlier? Is there documented evidence to validate the "better gas seal" claim? Is there "short chamber" patent?

In the recently published book "The Parker Story" the Remington vintage specification sheets on pages 164 to 169 call for a chamber 1/8-inch shorter than the shell for which it is intended. I have a 1930-vintage VH-grade 0-frame 20-gauge and its chambers are 2 3/8 inches intended for the old 2 1/2 inch shells, eight years after the 20-gauge Super-X shell was introduced in a 2 3/4 inch case!!

New subject: Why would manufacturers continue to make 2 5/8" shells 15 years after they had adopted a 2 3/4" standard?

Presumably because 2 5/8" shells were designed to work in 2 5/8" chambers with a maximum 1 1/8oz shot load AND those shells worked equally well in 2 3/4" chambers. If there was gas leakage around the overpowder wad or in the forcing cone, no one was the wiser...or complained apparently. We shoot 2 3/4" shells in 3" chambers today (ex Ruger Gold Label) and no one raises an eyebrow. Conversely, 2 3/4" 1 1/4oz loads were NOT DESIGNED to work in light guns with 2 5/8" Chambers.

Thank you Mike. One mystery solved. I think I will stick with the thin flexible Gun club 2 3/4" hulls from now on. They seem to hold up pretty well.

One thing I would like to insert into this thread;
"Years" prior to Bell & also some time prior to Thomas as well, actually the late thirties, British ammo makers pretty well settled this matter. Upon introduction of the "Fold"/"Pie" crimp overall length of the "Loaded" cartridge became shorter. To accomadate the same load internal capacity had to be increased. Whether they acomplished this by reducing base wad height, wad thickness or wall thickness or a combination of these I have no idea. Anyway there was then a fear that these shorter shells (nominal 2½") would be mistaken for 2" shells due to their shorter length. Subsequently, experimentation was carried out with case length to give a similar "Loaded" length to the older roll crimp shell. Testing revealed that as long as the load was the same pressure & balistics remained virtually unchanged. "NO" drastic change was noted in pressure, velocity or recoil. All of this is reported on by Burrard. This work was not done by Burrard himself, but by the makers. Burrard was not so Egotistical as to think results could only be determined by "Himself", but relied heavily upon those in position to "Know". I do not have any old fired English cases to measure, but it is my understand that from approximately WWII time on all British "Cartridges" "Designed to be fired from a nominal 2½" chambered game-gun closed with a fold crimp have a "Fired Length" longer than the chamber they were "Designed" for. "IF" this can be proved not the case I will then stand corrected. As stated several times here the answer is "Designed Pressure", not case length up to a point. The British's conclusion was shells should "NOT" be used having a "Loaded" length long enough to enter the cone, as this could very well inhibit the opening of the crimp, leading to excessive pressure.

2-piper, I do know for a fact that an opened 12 gauge, old style AA case is the same length as a Gamebore "Super Game" hull which states on the box that it is 67.5 mm and safe for use in 2 1/2" chambered English guns.
As I recall, the Gamebore kicked quite a bit more.
This was my first hint that paying $10 a box for special ammo is not always all it is cracked up to be.

Steve, for the # of shells you plan to shoot, cutting 2 3/4 plastic shells down to 2 1/2" and loading on a MEC progressive is not bad. It does require the 16 ga overshot card, but no other modifications to your press. Light loads made this way have less percieved recoil than most factory 2 1/2 shells. Others may disagree, but I have found light 7/8 oz loads will break any clay that I have the ability to hit.

"My mind is made up, don't confuse me with the facts".
This seems to be the prevailing philosophy.
Hopefully someone will answer Chuck's request
(but I honestly doubt the facts will come from the "engineers" out there).

I had the audacity to cite Mr. Bell's article in the 16ga. forum, when asking about this
same issue concerning my Manufrance Ideal prooved for "PRESSION 1100 KILOS".
I mentioned I was using 67mm shells loaded to CIP standards and received a sanctimonious
bashing for it.
To make a long story short, I was ostracised and frankly felt relieved.

JC(AL)

My goodness JC-I'm sorry if that was your reception on 16ga.com
Do you recall when you posted so I can look up the thread? And who was the 'basher'?

I entered this thread quite late, so please forgive me. If I am not mistaken, even though Mr. Bell may not be a graduate engineer, his partner in the investigation was Tom Armbrust, who I believe IS an engineer (ballistic engineer?). As a graduate engineer myself, I find no problem following documented and properly done experiments by a field experienced non-engineer, especially when assisted by an expert in that field. Following Mr. Bell's admonition, using shells whose PRESSURE IS DESIGNED FOR THE GUN, I find no problem with my 2 3/4 reloads (Federal paper hulls) which I make having approximately 6,000 psi in my older guns with shorter chambers (2 1/2, 2 9/16, & 2 5/8").

If anyone wishes to have a spreadsheet of low pressure loads compiled from various powder manufacturers' reloading handbooks, please send me a PM with your email address. I will send the multipage spreadsheet as an attachment to the return email. Jim Haynes

Revdocdrew, sorry, I do not remember. And I also apologize for not mentioning that
there were exceptions like Utah and surely yourself there, but.....

JC(AL)

This Eley catalogue page explains itself as far as case lengths go:



67,5mm for 2,5" guns.

JC(AL)

Seems like an excellent time to point out that 2 1/2 inches is actually 63,5 mm. And that 65 mm is 2,559 inches, that 2 9/16 inches is 2,563 inches (who wants to quibble with 0,004 inches?), that 2 5/8 inches is 2,625 inches, which is 66,68 mm (can we approximate this to 67 mm?).

Also seems like a good time to ask ---"Are there really any 2 1/2 chambers on those old double so marked?"

But, what is 1/16 of inch among fellow posters, especially in the midst of a lively discussion? Even 1/8 inches?

Niklas

The chambers of my 1922 20g Parker were closer to 2 3/8", and the recoil was WICKED with 2 3/4" AA 7/8 oz. target loads (the ONE shot I took!) No doubt the case mouth was extending into the forcing cone.

Thanks revdocdrew,

Now, to keep my metric sanity, 2 3/8 is 2,375 is 60,33 mm.

IF those AA target loads really do have 70 mm hulls, well, then, 9,67 mm of extra hull would sure give some extra recoil, at least in my personal experience. More extra recoil than I got the one time I fired some true 70 mm hulled-ammo in true 65 mm chambers.

My personal standard, as appreantly is yours, is that if a few mm longer hull gives distinctly more recoil than hull same lenght as actual chamber lenght (same loads in hull), THEN that longer hull is raising the chamber pressure, which increases both muzzle velocity and recoil. MAYBE the increase in pressure still results in pressure the old gun can handle for thousands of rounds, MAYBE. I personally will stick to hull lenghts same as chamber lenghts (in the actual 65 and 67 and 70 mm chambers), or to the use of 67 mm hulls in 65 mm chambers of my old guns. I might even be willing to use lower pressure 70 mm-hulled loads in 67 mm chambers, BUT, I have done no testing in my old doubles.

Niklas

Juan Carlos,

I do want to make a quick distinction. I was referring to the 16ga reloading group that Russ Gray founded and is email and Yahoo based. 16ga.com is a different animal and the two groups while having alot of overlap in membership are NOT the same.

I am registered at 16ga.com but didn't find anything there that the 16ga reloading group and this site didn't already offer.

Best regards,

Niklas;
I have wondered many times about that 2½"/65mm my self, since is as you pointed out not an exact conversion. On page 254 of Greener's 9th edition he shows a drawing of "The 12-Bore Cartridge Chamber". Along with dias ranging from .813" down to .798" at approx ½" increments I suppose he shows the length as "2½" or 2 9/16" Long" + an .074" rim c'bore. This would give an overall depth of from 2.574" to 2.636" (65.4mm/2 9/16") to (67mm/2 5/8").

Mike, sorry for the mix up. There was another poster there who is also "one of us",
and he was one of the exceptions.

The mentioning of my "16ga.com" episode was just to make a point and not really a
complaint.

JC(AL)

2-piper,

One can make a strong case that cartridge names often give only approximate information about the dimensions of the bullets, amount of powder and case lenght. One can suspect there is some of that imprecision in dimensions and specifics for shotshells. Actual chamber lenghts, hull lenghts, shotsizes, shot weights, etc. being some of the specifics that seem to often diverge from nominal.

Is there not some saying in English that "Consistency is hallmark of constrained intellects." ?

Niklas

Well friends:

Once again we have a demonstration that the simple answer is not alwasy the right answer, and even the right answer SOMETIMES does not make a hill of beans worth of difference.

Thats where judgement, based on knowledge and experience, becomes relevant.

Just thoughts ...

Regards

GKT

The European switchover to sillimeters and the early misguided efforts to slowly switch over and "blending" systems may have contributed to this?

[quote=... Thats where judgement, based on knowledge and experience, becomes relevant. [/quote]

Or even better, getting real data.

JC,
there are quite a few of us who left that 16 guage.com,I dare say you are in good company! Of course with the exception my friend Drew and couple of others ,untill they are able to clean it up and remove at least one poster we ain't missing much.
Don't feel bad there is a long list of "left the 16 gauge board"
we could start our own group in fact.
Best,
Dave

Maybe Chuck, but I always thought English folks were capabile of such all by themselves. When folks are calling 2 9/16 and 2 5/8 inch chambers "2 1/2", I would think they are already safe from rational advantages of metric system. Is excentric a good word here? One that Brits are proud to wear?

Don't forget that even USA's NASA has been reported to have sometimes been unable to square the metric units with English ones, with notable failures resulting.

Niklas

Dave, thank you! I am very happy to be in this company, :-)

Best to you too.

JC(AL)

There seems to be an understandable confusion among many posters as to the use of proof terms as a historical point of reference and the way that modern ammunition manufacturers cater for these.

A British gun stamped 2 1/2" or 65mm or with a diamond with a 'C' inside it (which mark you get depends on the age of the gun and when it was proofed)is designed for a 'normal' game load.

It is proofed (and in some years also stamped) with a service pressure of 3 tons per square inch. You need to consider the 2 1/2" chamber length, because you do not want the end of the crimp entering the forcing cone, failing to open fully and therefore increasing pressure. Ammunition in cases of 65mm, 67mm and 67.5mm is olny allowed to develop pressures in keeping with guns proofed at this (lowest) proof test.

BUT

You also need to be aware that modern 70mm cased shells are allowed to develop higher pressures because a gun stamped as proofed for 2 3/4" shells will have longer chamber, thereby acccommodating the crimp and allowing it to open fully but also because the proof pressure for these guns is done to 3 1/4 tons per square inch.

Therefore, a 24g 70mm shell may have a lower pellet payload than a 30g 65mm shell but it may well produce higher pressures.

In the UK, this is common knowledge and no shooter would put 70mm cased shells in his 2 1/2" game gun any more than he would put diesel in his motorcycle.

A few cases in poit:
My 1889 Purdey - has 2 1/2" chambers and is proof tested to 3 tons per square inch. In it I regularly and safely use the following:

34g bismuth shot loads 'Eley Maximum' brand in 67mm cases in boxes marked 'Suitable for guns proofed for 2 1/2" shells'.

30g Game Bore Pure Gold lead loads in 65mm cases marked as above.

24g Express HV lead loads in 65mm cases,marked as above.

I do not use:

White Gold 28g lead in 70mm cases marked 'suitable for use in guns proved for 2 3/4 inch shells' because although they are lower in pellet weight, they are more powerfully charged and the cases will not open fully in the chambers of my gun.

That same goes for any case marked 70mm or 2 3/4".

I hope that helps a bit - and I apologise for the grumpy tone of my earlier (early morning pre-coffee) message - I stand by what I said but I should have worded it more respectfully.

Smallbore
After reading your post above, I can see your perspective and why you posted your thoughts in the earlier post. UK logically limits pressure standards to progressively higher pressures for progressively longer shells. Simple, logical, and fits with the progression of both shell length and gun strength. From what I've learned here from our more historically aware members, American shell length progression and pressure progession follow a similar path.

However, in my earlier post, I was referring to reloading. As such, pressure can be controlled regardless of shell length. Since I have an instrumented test gun with a chamber that matches my field guns intended to use the reloads, I have relavent data regarding any restriction that may increase pressure due to any constriction caused by a long shell/short chamber.

From your perspective, I'm sure you are still wondering WHY? Why would I want to do this even if it's possible to do safely in this manner? Well, it's probably been a long, long time since I saw a shell less than 2 3/4" in my part of the country. I could order them for something like $8-10 a box and get whatever load the mfrs chose to offer. But, being of the type that likes to go my own way often, I chose to work up my own low pressure loads, the long shell, short chamber was simply a matter of bypassing a step (cutting long shells down) if I can get the same performance.

With my limited testing, I've convinced myself that it's a practical and safe approach and eliminates a trimming step in the reloading of the only commonly available length of shells here. I've also done enough pattern tests to believe the pattern is good out of my guns with these loads.

Smallbore

You need to chill out bud. Nobody on this board is advising anyone to shoot anything. They are simply stating what they practice or have read.

Maybe you should try preaching to those who participate in some seriously dangerous sports such as mountain climbing or auto racing. Plenty of people actually die every year in those sports.

The folks shooting 70mm shells in 65mm guns have no desire to make excuses for what they do so you don't need to excuse them.

Can we all be dismissed now kind sir?

Jim

A couple of points:

First, everyone seems to assume that Mr. Bell has no "degree" in engineering, therefore his research is invalid. I have corresponded with him on numerous occasions, and can confirm that he is, in fact, a degreed engineer. Even if he weren't, I've seen recent research (in other fields) from degreed scientists that was pure junk, and I've seen other research done by laymen that was flawless. A degree doesn't equal competence, it's just a starting point. I immediately see red flags when someone tells me to "believe what I say because I have a degree". I have those degrees, too, and I know colleagues with the same degrees that I wouldn't trust to have sense enough to come in out of the rain. They are the ones who seem to crow the loudest about their degrees (insecurity, perhaps?).

I have seen the term "fools" and similar used in this thread describing the practice of using longer shells in shorter chambers, even though they are low pressure. I have seen real data produced to support the practice from several sources done by different organizations at different times (eras, even), but oddly, NO data of any kind that shows it to be unsafe. If it is such an obvious danger, where is the data that shows it? Surely if it is such common knowledge, someone had to have proved it somewhere. In the case of Bell's research, they used an industry-standard test barrel (Mr. Armburst's), not some home-made device. If that data can't be trusted, then how could we trust any data from the industry?

Someone already pointed this out, but the analogy of 2-3/4" shells in 2-1/2" chambers is the same as 3" shells in 2-3/4" chambers is completely ignorant of the situation as it exists. There simply are no low-pressure 3" shells produced anymore (they all say "magnum" on them). The reason we don't do this is the inherent PRESSURE of the shell, even when fired in a 3" chamber, not the length.

Someone mentioned that it was equally stupid to shoot a gun that is out-of-proof. OK, then most of the early American guns are out of the question, because they were never in-proof, even when they left the manufacturer. But do we really believe that these stout-barreled, heavy guns can't handle the pressures of the little lightweight British and European game guns of the same era with proof marks on them?

If you feel, or "know" that the practice of 2-3/4" shells in 2-1/2" chambers is unsafe, or you just aren't comfortable with it, then fine. I support your decision to avoid the practice. But unless you can provide data to prove the results, please refrain from the smugness and name-calling. As the saying goes, money (or data) talks, and the other stuff...walks.

I just re-read what I wrote. JEEZ I've gotten crotchety. It's gotten way too late and I've got a gobbler to chase at dawn tomorrow. I'm off to bed, so no more tirades from me to suffer through. I'm sorry, fellas, I'm really not that grumpy!

Ever messured shells after firing?
67,5 mm shell becomes 70 mm shell after firing.
An if you reload it again, you will reload 70 mm shell allready.

Well before Bell ever ran his "Finding Out for Myself" tests--which provide still more confirmation of the practice--the late British gun gurus Maj Burrard and Gough Thomas both reported on the practice of shooting 2 3/4" shells in 2 1/2" chambers, which has been common in Great Britain for some time (provided that the shells in question were made within the pressure parameters appropriate for 2 1/2" guns). And both Burrard and Thomas concluded that the practice was perfectly safe--although in Burrard's case in particular, he can be misquoted on the subject if you do not read ALL of what he said. Thomas gives the actual pressure figures for a 10-shot string, 2 3/4" Eley Grand Prix shells fired in a 2 1/2" chamber; same in a 2 3/4" chamber. There is no difference in pressure and velocity from one to the other.

It is very easy to reload 2 3/4" 12ga hulls, especially 7/8 oz target loads, to pressures of under 6,000 psi. At least here in the States, most of the 2 1/2" shells we can find are field loads vs target--heavier shot charge, greater velocity, greater pressure. So chances are you're actually doing your old gun a favor by shooting low-pressure 2 3/4" reloads in it, unless you can find a good source of low-pressure factory 2 1/2" shells.

Well said, Larry!

Well it seems that some people are going to shoot the longer shells in shorter chambers anyway.
On some of the drawings of the forcing cones, and the length given of the chambers by various manufacturers, I'm still going to abide by using 2 1/2" low pressure shells in 2 1/2" chambered guns because I still don't believe that the longer shell opens fully creating more pressure.

As to the statement made by vh20, I was the one that gave the statement of using a 3" shell in a 2 3/4" chambered gun as a comparison of 2 1/2" to 2 3/4". Nowhere did I state that it was low pressure, it was just an analogy of using a longer shell in a shorter chamber.
Also you stated that older guns were never in proof even when they left the manufacturer. Wrong, they tested their guns before leaving the factory with loads that were twice the powder and shot of the loads available at the time. (Hunter Arms Co.) They just never put any proof mark on the barrels until the 1920's on some.

"The reason we don't do this is the inherent PRESSURE of the shell, even when fired in a 3" chamber, not the length"

Actually the pressures in a 20 ga. 2 3/4" Heavy Field Load 1 1/8oz shot is equal to the pressures in a 3" of 1 1/8 oz of shot.(Lyman's 5th Edition) 2 3/4" shells also had Magnum written on them.
Yes the loaded shells do cost more to buy, but there are companies out there that sell componants including 2 1/2" shells for reloading.

It's like one previous poster said, why encourage someone that is new and has a 2 1/2" chambered gun to shoot longer shells in a shorter chamber, it must be ok becasue he read it here.

It has been noted in this discussion that American manufacturers often chambered short even though longer hulls were in use. I find this typical hang tag from Parker to be quite informative. Look at the chamber length and then the recommended shell. And these were from the days of thicker paper hulls. Today's plastic hulls are much thinner, offering even less constriction in the forcing cone. For me, I'll go with what the old men suggested. They wanted the hull to open up well inside the forcing cone to provide a better gas seal. Even though today the plastic wad is universal I think the same principle applies.

Larry;
To borrow from Jim, "Well Said"
To comment on this statement "although in Burrard's case in particular, he can be misquoted on the subject if you do not read ALL of what he said." This is very true. It is in fact "Fact" that both Thomas & Bell were guilty of this, taking his "Warning Against" using the higher pressure "True 2 3/4" shells in guns built for the normal 2½" load as complete condemnation of hulls longer than the chamber. He did of course also fully cover the putting of the 2½" load in the longer hull with no undesirable effects.
It might also be mentioned that Bell did in fact fire some "Low Pressure" loads put up in 3" cases in 2½ chambers which stayed within the pressure range for the gun. He "Did Not" advise doing this purposely but checked it out just to see what would occur if it happened accidently. Note this was not a factory loaded shell as there are, as mentioned, no factory loaded low pressure 3" shells.
Personally I am not too concerned about the fired case lapping into the cone a little, but would never intentionally fire a shell in which the loaded case entered the cone (likely to occur with the 3" hull in 2½" chamber. The pressure begins to fall virtually with the first movement of the charge, so long as the crimp is not impeded in it's initial opening, pressures would seem to be not much affected.

Larry,

I have selectively quoted from your previous post to focus the point of my question.

Are ANY of those "2 1/2" inch chambers really 2,50 inches? If 2-piper's post quoting diagrams from Burrard is accurate (that is, Burrard's diagrams are accurate), perhaps NONE of those "2 1/2" inch chambers were 2,50 inches (63,5 mm) but really 2 5/8 inches (67 mm). Firing a true 70 mm hulled shotshell in a 67 mm chamber is quite a bit different than firing it in a 63,5 mm chamber.

It keeps seeming to me that talking about firing 2 3/4 inch shotshells in a perhaps (apparent, even really) non-existent chamber lenght (2 1/2 inches)is really misstating reality, thereby keeping discussions like this one in fantasy land.

Perhaps this discussion might converge IF it were widely understood that expression "2 1/2" inch chambered shotguns and shotshells really means 2 9/16 (16 gauge) or 2 5/8 (12 gauge).

I am still awaiting reportage of shotguns with true 2,50 inch chamber and factory loaded shotshells that are true 2,50 inches long.

But then, maybe 65 mm shotshells in Britian are really 63,5 mm (Eley shotshell box shown in one post) and in Russia 67 mm shotshells are really 70 mm (Geno's post).

Niklas

I have a 55 gal. drum of old AA hulls that I load to shoot in damascus Parkers with 2 5/8" chambers. The load is from IMR data and I have had it tested by Tom Armbrust @4100 - 4250 PSI in a 2 3/4" chamber. I'm very comfortable with this. I just measured a random sample of these hulls and not one was over 2 11/16" in length. I would suggest that manufacturing tolerances in case thickness, internal base height, variation in powder and primer lots might cause more pressure variation than 1/16" to 1/8" inch in case length. Forcing cone configuration would be another factor. I don't believe you can really tell what you have in the way of pressures unless you test in the individual gun in which the loads are to be fired. I also believe that if you err on the side of conservatatism, it doesn't really matter.

I didn't say that, Niklas, but it's fact that shell becomes longer after firing. Take brand new shell, messure it, reload it, fire it and messure it again.
That's why factories load heavy slugs in 67,5 mm shells for 70 mm chambers.

The chamber drawings I mentioned were from Greener, 1910 (9th Edition)
From Burrard:
Vol II page91;
"The ordinary 12-bore cartridge is ""Nominally"" (emphysis mine) 2½ inches long, although to be exact the unfired (I think he is here referring to a new unloaded case) case is 2 9/16 (65mm??) inches in length."
"The standard American case was always slightly longer than the nominal 2½ inches and was actually 2 5/8 inches in length.
Vol II, page 154;
"In 1938 I tested some of the first lot of British fully crimped paper-tubed cartridges which were issued. These, as has already been explained, were loaded in 2 9/16 inch cases. I fired a series of ten shots for pressure and obtained very even and perfectly normal results. Two months later I tested another lot which were loaded in ""2 3/4"" inch paper-tube cases. the shot charge in both lots was 1 1/16 ounce and the powder charges were similar. I fired twenty-five shots for pressure and again obtained a very even series with ""NO"" higher pressures than those given by the first lot. Since 1946 I have tested many more lots and these results have ""PROVED"" quite definitely that ""For All Practical Purposes"" any increase in pressure due to the ""LONGER"" case really does not exist ""Provided"" the correct powder and shot charges for a nominal 2½ inch cartridge are used. It is true that all American fully crimped cartridges loaded with but 1 1/8 ounce of shot develop pressures which are considerably higher than those given by the corresponding British cartridges, but this is due to the relatively higher powder charge adopted by the Americans rather than to their use of the 2 3/4 inch case."
This was all virtually settled well over a half century ago, what part do we fail to understand??
The "Load" should be suitable for the gun in question.
The "Loaded" shell should have clearance & not enter the cone.
""IF"" an exceedingly old gun with very short & abrupt cone results in tearing of the crimp, use shorter shells.
Otherwise concern yourself with pointing the gun.

Thanks 2-piper!

Now, does that Burrard feller give comparable informations about chambers of those "nominal" 2 1/2 inch chambered shotguns?

Niklas

Geno,

ALL the factory slug loads I ever tested did, indeed, stretch the cases. Chamber lenght was not a factor in this. However, shot loads did not stretch the case when fired in chamber same lenght as fired case AND with chamber pressure normal for such shotshells (have seen with rough interior cases and dry, rough and tough fiber wads).

Niklas

Since some of you are using Burrard and Gough thomas to support thei sposition, i offer the following quotes from the two gentlemen in question:

Gough Thomas:(1975) "Cartridges were hitherto denoted by the length of the unloaded case, which was never greater than the length of the chamber. Since crimp closures became the rule, they have been denoted by the minimum length of the chamber for which they are designed, as stated on the carton THEY MUST NEVER BE USED IN CHAMBERS OF ANY LESSER LENGTH".

Burrard: (1932)"If cartridges are used which are too long for the chambers the pressures generated will be excessive and will cause irregular patterns irrespective of the risk of straining or even smashing the gun.....For these reasons it is always important to use the proper length of case for a particular gun, the proper length being always stamped with the proof marks on the barrel flats"

Still, these authorities, the two proof masters and the whole of the British gun trade must be wrong since one or two of you have been using the wrong ammo and have not yet shot your guns loose. I do not find your arguments compelling.

JDW,

(JDW:)As to the statement made by vh20, I was the one that gave the statement of using a 3" shell in a 2 3/4" chambered gun as a comparison of 2 1/2" to 2 3/4". Nowhere did I state that it was low pressure, it was just an analogy of using a longer shell in a shorter chamber.

No, of course you didn't, and I didn't say that you did. I'm not sure what you mean by that, it wouldn't have made sense. My point was that it is NOT the same BECAUSE there are no 3" low pressure shells manufactured anymore (although there used to be). You didn't mention ANYTHING about pressure, and that is where my disagreement came from. We don't stick 3" shells in 2-3/4" guns because they are magnums, and unless we know the pressure, we EXPECT it to be very high (same with the 2-3/4" magnums you mentioned). I can find some 3" loads in the manuals that are close to being low enough for my comfort, but not quite. Then we expect we are going to add another 10 or 15% more pressure to that because of the mismatched length. In other words, your analogy violated the premise of the practice of shooting longer shells in shorter chambers to begin with, that being that the longer shell must produce a pressure in its designed chamber length that would be appropriate for the shorter-chambered gun. Bell's test showed that even the 3" hull, if loaded to appropriate pressure, didn't cause drastic pressure increases in the short chamber, but generally speaking, 3" hulls are never loaded to appropriate pressure by any manufacturer.

(JDW:)Also you stated that older guns were never in proof even when they left the manufacturer. Wrong, they tested their guns before leaving the factory with loads that were twice the powder and shot of the loads available at the time. (Hunter Arms Co.) They just never put any proof mark on the barrels until the 1920's on some.

I'm quite aware of that, and later on they even marked them as such. But try and sell one of these guns to the gentleman in England who brought the subject up. You won't be able to because they won't accept it (i.e.illegal). They are most assuredly NOT in-proof as to their definition, and that is what I was addressing. In-Proof means a Proof House has certified it and it has not been altered or damaged since, not just the manufacturer's assurance that it is OK (which I am personally fine with, by the way).

"The reason we don't do this is the inherent PRESSURE of the shell, even when fired in a 3" chamber, not the length"

(JDW:)Actually the pressures in a 20 ga. 2 3/4" Heavy Field Load 1 1/8oz shot is equal to the pressures in a 3" of 1 1/8 oz of shot.(Lyman's 5th Edition) 2 3/4" shells also had Magnum written on them.

Again, the premise REQUIRES that the longer hull must generate a low enough pressure in its proper chamber to be appropriate for the shorter chamber (I don't have Lyman, but I'm willing to bet lunch that neither of the two loads listed are low pressure). If you skip this requirement, then the whole thing is null and void, and the discussion meaningless, and yes, all your comments on the danger could be realized.

I certainly didn't mean to offend, but I guess what I was trying to do is explain that the example you gave violated the premise the whole practice is based on. If you HAD stated 3" LOW PRESSURE, I would have said that the only data available says "no big increase in pressure". In the end, all we have to go on is data, and gut feelings. Your gut feelings obviously tell you not to do it, and that is great. I would never encourage you to. But there is NO data that I've seen that supports it. Those in the "don't do it" camp seem to imply that it is common knowledge and only a fool would try it. My question, then, is if it is common knowledge, where did we get it from? Someone had to have proved it once, right? I would just like to see those results so I can make better decisions in the future for my own practices.

I would not stick a factory 2-3/4" shell in a 2-1/2" gun because we don't know the pressure, but we do know that it could be (and likely is due to the popularity of autoloaders) near or at SAAMI max. But careful reloading practices ensure that we CAN know the pressures of our handloads (and control them) and it is ONLY then that the option becomes available. (Plus the exception of the few boutique factory loads that have published low pressures).

I think there has to be closure on this subject, it doesn't seem to be any different from the begining.

I thought that I had said modern guns when I said about putting a 3" shell in a 2 3/4" chamber. Meaning new guns. I wasn't refering to low pressure 3" shells, again I was trying to make a point about using a new manufactured 3" shell in a new modern proofed 2 3/4" chambered gun. To me that is the same difference as what the topic is.
As someone stated earlier, more gun manufacturers are making guns now with 3" chambers because they know people are going to stick a 3" shell in a 2 3/4" chambered gun.

I must have missed the part where the gentleman was from England, I thought he was from S.C.

Also did you get a long beard this morning?

JDW, there shouldn't be any problems shooting a factory 3" shell in a modern American double with 2 3/4" chambers. Why not? Well, because the SAAMI pressure standards are THE SAME (11,500 psi) for both 2 3/4" and 3" shells. However, why would one want to do so?

2 3/4" in a 2 1/2" chamber, on the other hand . . . For one thing, here in the States, 2 3/4" is our standard case length. All sorts of very low pressure reloading data is available for 2 3/4" 12ga hulls--lower pressure, in fact, than the vast majority of the factory 2 1/2" shells available in this country. Not to mention a lot cheaper! So why not use the reloads, to the appropriate pressure standards?

As far as the actual chamber length of a gun with a "nominal" 2 1/2" chamber . . . I have a pair of such guns, marked 2 1/2", and unaltered. Using my chamber gauge, I get just slightly over 2 1/2"--probably less than 2 9/16", and certainly less than 2 5/8".

Some measurements of once-fired American and British shotgun shells, all plastic, all crimp-closed (with a digital caliper):
Remington STS: 2.69"
Winchester AA: 2.70"
Federal Gold Medal: 2.71"
Gamebore Super Game (Nominal 67MM): 2.63"
Eley Blue (Nominal 70MM): 2.59".
Note that the 67MM Gamebore (marked on the box as suitable for guns with 65MM or 2 1/2" chambers) is only .07" shorter, on average, than American factory 2 3/4" hulls. That's almost exactly 1/16th inch--not likely to go very far into the forcing cone.

As for Gough Thomas, I refer once more to his "Gun Book", chapter entitled "Danger in Case-Length"--the conclusion of which is that there isn't any danger in case length. He specifies that the test he conducted used crimp-closed shells in 2 3/4" cases (to pressure standards appropriate for 2 1/2" guns) and had them fired in pressure barrels with, first, 2 1/2" chamber; and then 2 3/4" chamber. NO DIFFERENCE IN PRESSURE OR VELOCITY.

I'm not interested in convincing anyone here to use 2 3/4" hulls (even if loaded to low pressures) in 2 1/2" chambers, unless they wish to do so. I am presenting the evidence, which I find to be overwhelmingly convincing--and from 3 separate sources who conducted separate tests (Burrard, Thomas, and Bell)--that, providing the shell is loaded to the service pressure appropriate for a 2 1/2" gun, the 2 3/4" hull, in and of itself, presents no additional danger.

And Joe, that's a very interesting Parker hang tag. At the time that gun was built (1902), there would have been no difference in pressure between a 2 3/4" and 2 5/8" American factory shell. It was not until the 1920's that the higher pressure, "modern" American 2 3/4" loads appeared. Once more, the extra length would not have made a difference.

Control of "BREECH PRESSURE"is the key safety concern when shooting 2 3/4 shells in British 2 1/2 chambered guns.Quoting from Eley literature they state,"Some 12G,cartridges having 2 3/4cases can be safely used in guns having 2 1/2 chambers!"
If you measure your typical 2 3/4 shell you will find that the actual loaded length is 2 1/4 - 2 5/16. After firing the case length measures 2 5/8-2 3/4. [You will also find that cartridges sold as 2 1/2 have almost the same dimensions as the 2 3/4 shell!]The thickness of a plastic shell case is .020 approx; therefore this 1/4 inch extension of the shell case can easily be accomodated, without constriction below bore size, in the the forcing cone as it transitions from chamber diameter to bore size.
Noted English balistics experts, Burrard and Garwood [Gough Thomas] have published test results that show 2 3/4 shells correctly loaded for the design pressure of 2 1/2 chambered guns can safely be used in nitro proof [In Proof] British guns with 2 1/2 chambers.
I use the following reloads in 2 1/2 chambered guns:-
22.0 Gr.Dupont SR 7625 powder.
Winchester AA Hulls.[or similar 2 3/4 case length shell]
Remington 29930 wad.[or similar]
1 1/8 ozs; shot.
Approx breech pressure is 6900 LUP.

Chuck:

I hope you comment is not a dig.

[quote=... Thats where judgement, based on knowledge and experience, becomes relevant.

Or even better, getting real data. [/quote]

I hope you understand that I wasn't suggesting "wives tale" decision model or anything like that. Experience produces the ability to use judgement, and experience includes the gathering of real data. In this case that measn seeing what the pressure gun says and not listening to cracker barrel "truisms" such as "black powder is lower pressure than smokeless". I am always in favor of real data.

In engineering the judgement part comes in when you look at the data and make a decision as to whether or not the differences make a "hill of beans" or whether a given option is worth the additional cost or risk versus the actual benefit.

regards

GKT

[quote=JDW]
I thought that I had said modern guns when I said about putting a 3" shell in a 2 3/4" chamber. Meaning new guns. I was trying to make a point about using a new manufactured 3" shell in a new modern proofed 2 3/4" chambered gun. To me that is the same difference as what the topic is.

OK, got it. I believe that the data has shown that if both the 3" shell and the 2-3/4" shell are loaded to the same pressure, and the 2-3/4" chambered gun is designed for that pressure, then there will be no significant pressure rise (10 to 15 %, significance is up to the one interpreting the results). But as someone said before me, there really is no motivation to do this because there is no cost or convenience-based motivation. In fact, 2-3/4" shells are easier to find and cost less to begin with. But whatever the outcome or motivation, I must agree with you that it is something we generally don't do.


(JDW:)I must have missed the part where the gentleman was from England, I thought he was from S.C.

Yes, London in fact, according to his profile. And I don't disagree with his view point when I take it in context with where he is from and what he's used to over there, and what he probably meant. But I wanted to point out that there are other guns being discussed than British, and in the end, wall-thickness and condition trump a set of proof marks, especially on guns that never had them.

Also did you get a long beard this morning?

Heh! Well, no. But I did have an enjoyable hunt. We are having a record-setting cold spell this week, and the wind has been up over 20 mph for 3 days straight. I got in the woods among the swaying trees this morning and could hear one gobbler proclaiming the Gospel with conviction. But, he was 100 yds. across the property line roosted on the edge of a field on that property. That was where he intended to go and I could not convince him otherwise. He must have stayed in the tree for over an hour past normal fly-down time, riding the swaying limbs and arguing with a bunch of owls. I had two jakes come to investigate me up to about 15 yds. and I managed to not spook them, and watched them feed away. By 8:00 I was frozen, and packed it in. Enjoyable morning, though.

ONE MORE TIME:
You have to read in the "Context" of which it was written. The part SmallBore quoted from Burrard is in fact totally out of the context to this question. It applied to loading, as he called it, the "True" 2 3/4" cartridge, put up with 1¼ oz shot, a heavier powder charge, higher pressure & at the time he wrote that, in a roll crimped shell which would come about even with the end of the chamber as loaded.
I quoted to you "WORD FOR WORD" exactly what Burrard said concerning putting up the regular 2½" load in a longer 2 3/4" case when the fold crimp replaced the roll crimp. There was NO increse of pressure, Apparently you are totally unable to Read & Understand. This was also borne out by both Thomas & Bell.

Greg,
No, I didn't intend my comment as a dig (no offense intended at Mr. Digory Hadoake (sp) either). If it sounded otherwise, my appologies. I agree with your elaboration. Mine was more from the perspective that "knowledge and experience" was used in terms of previous experience and education applied to the current subject through association and extrapolation. When an engineering issue has numerous factors that influence the outcome, actual testing of the article with all the factors included sometimes is the best way available to assess the issue. (Example: when we build a new airplane, we do hundreds of tests even though we have much knowledge and experience with very similar designs from the past. This is because the interaction of many variables in the design create complexity in analyzing as opposed to testing the actual article) Hence my comment; "Or even better, getting real data."

Sorry 2-piper, but wrong again.

Burrard states on p.175 of Vol III about the crimped cartidge "I doubt whether its use can make any practical difference to the conclusions I have ventured to draw".

He goes on to mention the heavily loaded Eley Maximum cartridge, introduced in 1933 and still available from Eley (I use them loaded with bismuth for duck shooting).

"it contains a low-velocity load 1 1/4oz) ... but at a pressure which is normal for the standard 2 1/2" 12-bore load." (Again- showing case length and pressure to be key rather than pellet load).

On p.162 he illustrates a gun with 1 1/2" chambers used with 2 3/4" nirto cartridge.The barrels burst.

When manufacturers moved to crimp closed shells, they made the nominal chamber length markings they put on the boxes refer back to common proof markings:

I have in front of me a box of Hull 'Imperial Game' 28g 2 1/2" shells. The box states:

"These cartridges should only be used in guns proof marked for a shot load of at least 1 1/8oz and/or marked for a service pressure of at least 3 tons per square inch. DO NOT USE IN GUNS OF CHAMBER LENGTH LESS THAN 2 1/2".

Also, from box of Game Bore Pure Gold; "for 70mm case length; These cartridges are suitable for use in guns with a chamber length of 2 3/4" or longer, nitro proofed to a service pressure of 3 1/4 tons per square inch (900kg per square cm).

Ammo makers load 2 3/4" cartridges to higher pressures and they require higher proof charges to test for them. This is irrespective of the pellet load in the case.

So, the manufacturers say don't use 2 3/4" shells in 2 1/2" proofed guns. I also spoke in person about this with the Proof Master of the London proof house last week. He told me in very clear terms that it was not safe and that 70mm cases should only be used in 2 3/4" chambers.

I believe the message that goes out from here to readers should be 'Use the right ammo in your gun' not 'use the wrong ammo if you like because sometimes it is OK'.

There are issues of public safety here and we should be giving out the right messages. Too many people will come away from reading this with the impression that you can pop into Wallmart, pick up a slab of whatever normal 2 3/4" shells they have and happily fire them off in their 2 1/2" chambered Webley 700 with no ill effects. Bad idea.

I would like to thank L. Brown for confirming that at least two of those 2 1/2 inch chambered British doubles do indeed have 2 1/2 inch chambers. Hopefully, this is true in general.

Well before magnumitus became endemic, 65, 67 and 70 mm hulls were sometimes loaded with an additional 1/8 to 3/8 oz of shot and reduced powder charges. Old loading manuals often include various such loads, generally with pressure data showing normal chamber pressures. I have shot lots of those in older, but still strong, doubles, with heavy loads of larger shot (the ancient low velocity, heavy shot approach for waterfowl, etc.). Don't recall there ever being a fuss about these loads being unsafe in guns designed to hande these chamber and barrel pressures and breechface forces, guns still in excellent condition.

I do agree with Smallbore's concern about an unsavvy shooter using highpressure USA shotshells in an actual 2 1/2 inch chambered, lightweight British double. Do many such folks follow this Board? However, this is a BB where the savvy reloader and shooter can get rather detailed informations about ways to increase the versatility and satisfaction of their hobby. Many of us follow this BB closely for just such informations. So, can there be an acceptable balance of these two concerns?

Niklas

Niklas, Well said and exactly why I posed the question to begin with. I never thought it would develop into such s firestorm of strong opinions.

I do not recall a "Single" person here recommending to go out & "BUY" shells having a higher pressure than a gun was intended to fire, whether of the same or longer length. I did not omit that part of Burrard but you very conveniently keep omitting the part you don't agree with. That's fine, OK by me, but I don't feel I have given out any un-safe info. As I understand it the reason for changing from an "Ounce" proof to a "Pressure" proof was because of the situation you mentioned where a 1¼oz "Low velocity/standard pressure" was quite acceptable for firing in a "Normal" 2½" gun proofed @ 1 1/8oz. Many did not recognize this & thought it not with-in proof parameters. A similar circumstance was the changing of "Not-for-Ball" to choke. The change allowed shooters to "Think-for-Themselves" & realize a ball was quite acceptable as long as it was small enough to go through the choke. If you were to "MEASURE" all the fired shells made since the introduction of the fold crimp, & sold in the British trade in boxes marked "For use in 2½" chambers" or whatever is normal, I truly suspect you would be ABSOLUTELY FLABBERGASTED at just how mny of them were in fact longer than the chamber they were marked to fire in. You simply can't seem to understand we are not talking here of reading boxes, but putting up "Identical" loads in empty hulls by reloading. No one is recommending firing those loads made for higher proofed guns in a lesser gun.

I know this sound.
When I try to epxplain the same 2-piper said here on Russian board, some people tell me: Ts-s-s-s! Stupid-heads could hear this and begin to use hot 70 mm ammo in 65 mm guns.
For me it's good idea all stupid-heads would use the hotest loads in their weak guns, but I can bet there are only few of such around the world!

I suppose using a very low pressure 2 3/4 inch shell would be better than using a 2 1/2" round that produces very high pressures!

Another great When is an elephant not an elephant? argument!Been "loads" of fun listening to this and I'd have to say Niklas has got you all ("traindrivers" and otherwise) beat for "in the trenches" empiricism and apparently his research didn't require much more than a cheap slide caliper. When everything's "nominal" there are a heck of a lot of special cases each with its own specific risk factor which our many "take it on authority" gurus seem unable to pin down.

jack

It really is hard to "get one by" ALL of the folks on this board.

Niklas

Smallbore, did you discuss reloaded 2 3/4" cases with the proofmaster, or did you refer only to factory 2 3/4" shells? Many of us here have clearly drawn that distinction--as did both Burrard and Thomas, with their very clear warnings NOT to use American factory 2 3/4" shells in guns with 2 1/2" chambers. All of us agree 100% with those warnings.

We also have the issue of the nominal "67MM" Gamebore shell--which, you will note, I measured with a digital caliper to have a fired length of 2.63". That's almost exactly 2 5/8", or 1/8" longer than the chamber length of a 2 1/2" gun. Yet right on the box, Gamebore will tell you that that shell is suitable for use in guns with 2 1/2" chambers. If case length is the problem, how can that be so? Answer: case length is NOT the problem, per Burrard, Thomas, and Bell. IF the case is loaded to pressure parameters appropriate for the gun in question--and most of us on this side of the pond are reloading VERY low pressure 7/8 oz reloads for our short-chambered 12's, around 6,000 psi--it doesn't make any difference whether the case is 1/8" or 2/10" longer than the chamber. Tests by Burrard, Thomas, and Bell--using instruments to measure pressure--have shown either no increase in pressure from the longer case, or only a very slight increase in pressure.

When the length of the fired hull exceeds the length of the chamber by no more than 1/4", the danger comes not from the extra length, but from what's inside the hull to start with.

Steve-

I think you have masterfully stated in one sentence what has taken 10 pages of discussion! I suspect that a lot of the "do's and don'ts" were very valid for the guns and ammunition for the time of the rule.

This discussion is likely so full of passion because so many of the forum members have been using low pressure reloaded 2 3/4" shells in their shorter chambers for years without any problems and it appears that there is no credible evidence (all things being equal) that the longer shell length significantly increases pressures.

Nonetheless, who among us would not purchase 2 1/2" low pressure loads for our older guns if they were available at $3.59 a box?

I can understand why the larger manufacturers do not cater to this need. It is for the same reason new made private aircraft are no longer widely manufactured...product liability concerns.

Midway markets a very sweet 7/8 oz 2 3/4" 5000psi load which one would think ideal for an older damascus barreled gun...and no doubt Midway and Federal are very much aware that the consumer would use the load for these more delicate applications, so they expressly state that the load is not intended for damascus barrels.

Doug

Builder mentions getting unexpected pressure yield from shortened hull and Hartin crimp which if I remember right is a fold crimp of the remainder of previous factory crimp on top of overshot card. Makes me wonder about the relative "containment" strength of the various crimping methods and if this has any effect on chamber pressure. Does anyone know if either the Hartin or the outmoded roll crimp would generally be associated with a higher pressure yield than would the industry standard fold crimp, given same payload and charge?

jack

I think any of us that have read Sherman Bells articles in DGJ
as well as some of the English articles feel very comfortable with "2 3/4" ammo in 2 1/2 chambers. I use STS cases and 22.5
gr. 7625 with 1 oz of shot and they are low pressure and fine. As stated many times there is only about 100 psi increase and of course the STS and WW are about 2 5/8 in length.

Jack,

I have a bit of information bearing on this. I have long used the hartin crimp on 65 mm hulls (made by cutting down 70 mm hulls) and also under the star crimps of 70 mm hulls to give better (non dished in) crimps. The latter usage is generally with lightened loads that do not fill the case enough for non-dished star crimps. With these lightened loads in 70 mm hulls, I use 12 gauge overshot card wads in 12 gauge and 16 gauge overshot card wads in 16 gauge. "Normal" hartin crimp practice seems to be to use overcard wads one or two gauge size smaller (16 or 20 in 12 gauge, etc.).

With the addition of same gauge overshot card wad under normal star crimps I seem to consistantly get more complete burning of the powder and seem to get this same more complete burning if the hulls have been shortened. This seems as it should be because any strengthing of this "compound" crimp would logically occur along the hull walls. With sub gauge sized overshot card wads this same strengthening would not be expected.

I do have one chamber pressure datum and it does indicate that use of same-gauge sized overshot card wads does increase chamber pressure at least a few hundred psi, maybe even a thousand psi. However, there is not the degree of control on this result that I would like.

Niklas

In my Harten crimp on the cut down 2 1/2" Remington STS hull I was unable to get the 12 gauge overshot card into the hull due to the irregular shape of the open crimp and had to switch to 20 gauge overshot cards. These are the ones I had tested. I attributed it to an error in the published book. Intuitively, I would think that the Harten crimp using the 20 gauge overshot card would lower the pressure since it looks like it would be easier opening than a standard crimp. Intuition does not always work and Jack may have a point.

Since we're making a book out of this thread, I thought I'd ad some pictures 'cause I hate a book without pitchers.

This little unit is how far consumer products have come. Oehler was the first to introduce a consumer level of pressure measurement device in his "Ballistics Lab" quite a while back as I recall. It was expensive (still is) and didn't keep up with the times IMO. The Pressure Trace system is based on laboratory grade strain gages and a common PC with software that takes the raw strain data and crunches it instantly to useable data by factoring the strain gage calibration offset, barrel measurements, etc.. The sample rate is very high (a lot faster than the Oehler) and can provide very good resolution of peak pressure, even in pistols and high intensity rifle cartridges.




Using one of the common singleshots (H&R and similar) provides for a constant diameter (not highly tapered like a sxs) at the chamber and reduces the chance of measurement error of the wall at the precise location of the strain gage. Strain gages rely on known E-modulus (Young's modulus/modulus of elasticity) which is very consistant for steels (another reason to instrument a steel barreled gun instead of a damascus gun (maybe))




This trace is of a WallyWorld Federal 16ga shell. Note the pressure. I don't believe every SAAMI compliant shell is SAAMI max pressure, quite the contrary.

Chuck,
Can you relate time to distance from the breech?

Nah, I don't have any data on that. Jim Ristow at mfr for the PT had some data on rifle time/bullet travel down the barrel.

Oehler's Model 43 Ballistic Lab used basically the same type of strain gages as does his professional Model 83/84. When I posted about this device in the past, some were very skeptical. That's o.k., they should be. They should learn how and why this type of device collects data before they invest and trust in it. I've been around instruments nearly identical to this in years past for industrial applications and I'm comfortable with them.

Now we're getting somewhere. Be very interested to see more results Chuck and I'd be happy to send samples of some of the 2" and 2-1/2" shells I have.

Chuck,

Can that pressure transducer be used as well on old doubles? Say ones with little or no taper over chambers. If so, then the door is open to getting direct data on actual old doubles and diverse ammo fired in them.

Niklas

Nik,
The less taper in the wall thickness the better. It will work on just about any gun you can get an accurate wall thickness measurement on. However, nearly all the sxs shotguns I've seen have lots of taper on the outside of the chamber. This increases the likelyhood of a measurement error by the fact of where it's placed on the chanber and the span of the gage itself over a taper.

I looked for quite a little while to find a short chambered singleshot. But, it's the simplest way to go. I bought a 12g and a 16g as well.

I've thought of ordering a barrel blank and making my own bench pressure gun for this purpose, but I'm not trying for absolutes here nor do I test much. I worked up some loads a couple years ago and haven't taken it out since. This is the kind of thing a group of guys or a club could really benefit from. I bought it specifically to work up some loads for my damascus guns. I found my 1 oz load with components and pressures I was satisfied with and stopped. I'm thinking about working up a 1 1/8 oz low press load someday, for those phez trips to SD.

Wife says I have a point, on top of my head. Thanks for the assessment of the crimp situation.

jack

I don't think anyone is saying that all American factory shells will reach SAAMI max service pressure. That's simply a ceiling. The problem is, American ammo makers load to achieve constant velocity, using bulk powders. Therefore, while one batch of American factory ammo may be well under SAAMI max service pressure, the next batch may not be, because they've changed powders.

A careful reloader has a much more exact idea about the pressure of the loads he's working up than you do if you run out and buy a box of factory shells. All you know with the factory ammo is that it's within SAAMI parameters.

Regarding the case length of 2 1/2" shells loaded to pressures deemed safe for guns proved to a service pressure of 3 tons per square inch, all meet the pressure safety requirements of proof.

However, choose the actual shell depending on the forcing cone dimensions of a given gun. Those with steep forcing cones will be better suited to 65mm cases than 67mm or 67.5mm cases, even though the pressures are the same.

This is because the opened case will partially narrow the cone urther and prouce greater pressure. It is a matter of common sense that if your cases are ragged at the ends after firing, they are too long and you should use shorter ones.

I'm glad we all now seem to be in agreement that it is not safe to put factory loaded 70mm shells in a 2 1/2" proofed and chambered gun.

If your re-loads are opening out in the gun you are using and not showing any fraying, then they must be opening fully in the chamber and are likely not a problem. If they are fraying, then you need to use shorter cases or lengthen your chamber - which, of course requires the gun to be re-proofed.

Or, you could lengthen the forcing cone.

"I'm glad we all now seem to be in agreement that it is not safe to put factory loaded 70mm shells in a 2 1/2" proofed and chambered gun."


This is a very prudent statement. I can only ammend to say that it would not be safe to use 70mm shells UNLESS they are those that are of very low pressure..... i.e.: Under 7000 psi.

Page 8
This was a summation of what had already been posted & it still took 3/4 more pages to agree.

I would suppose that this is progress of sorts. I keep remembering threads like this that never seemed to come to this agreement, at least not before I quit reading them.

Niklas

LB,
I don't disagree with your assertion that pressures will change on a factory made load due to powder lots. I do believe that pressures will not likely be wildly all over the map, especially for popular high quality target loads. The consumers of a STS or AA load are shooting these loads because they can depend on them. Remember who they have to deal with, target shooters are a persnickety group if there ever was one. The least little thing upsets their carefully balanced biorythem, star alignment or whatever. A shell that has a different report than they're used to will set them off for sure. A Win AA 1 oz/1200 fps skeet load will likely never see near SAAMI limits just due to Win's need for a powder loading density similarity and velocity consistancy, and that they undoubtedly spec the powder, albeit the tolerance of the powder may be different than the stuff we buy. Promo loads are yet another animal, especially the high velocity stuff with heavy shot charges.

However, to be prudent, lot testing of factory ammo should be done for pressure data if unusual pressure limits are critical to your application/safety and that mfr doesn't provide pressure data in the packaging. Which brings me to ask; why should we trust an inquiry (letter, email, phonecon, etc.) from an ammo mfr regarding pressure, if it's not on the published data for that load? I get the impression that some of the sources of shorter shells that didn't publish pressure data have provided data in correspondence to those that inquired. Why would this be more trusted than Winchester, Rem, or Federal?

Taking advantage of all the previous interchange of information and data
I would selfishly appreciate feedback on the following combination I am going to
use (no 2,5 shells locally available and I have no reloading equipment)

-Manufrance Ideal 16/65 proofed/prooved to 1100 KILOS (1079 BAR according to some
conversion tables from <http://www.convert-me.com/en/convert/pressure>
-Locally made TEC 16/67 shells, 57mm unfired length with 26grams of #7 shot,
loaded to CIP standard 570 BAR (581.2 KILOS according to same tables,or 8,267lbs)

Local CIP Proof House (yes, 3rd World country does have a proper Proof House) told me
the TEC and Fiocchi shells made locally are extremely consistent in their pressures.
A lot more consistent than the imported shells from USA or Europe they have to test.

Even allowing for a 15% increase in pressure I would be a lot lower than the proof
pressure of the gun (unless my conversions are totally off).

Thanks in advance,

JC(AL)

All of the "2 1/2" shells I have seen have in fact been 67.5 mm.
I use the Eley grand prix and impax in paper.
I have never seen any specs but I believe these are fairly mild loads.
I have used black powder 70 mm reloads in my Damascus guns without issue having read both Thomas , Burrard and discussions here before.
However I now use the paper hulls from the aforementioned Eleys,which last longer as well.
Anyone have any idea what pressures these factory Eleys produce?

GDU

Chuck, not being one of those who has corresponded directly with shotshell makers, I'd hazard a guess on why they trust the responses given them by the makers of short shells: The makers of short shells would seem to be catering to their clientele, just as are Win/Rem/Fed. And their clientele wants shells which are within the service pressure parameters of 2 1/2" chambered guns. Win/Rem/Fed, on the other hand, are in the business of producing shells, within SAAMI standards, which go "bang" reliably when you pull the trigger, deliver consistent velocity, and--with the exception of some very light loads--have enough push so that an autoloader that hasn't been cleaned since last hunting season will still function.

Horses for courses, as they say.

Larry,
'seems a little thin to put faith in when fingers and eyes are on the line. Their choice I suppose.

"Can you relate time to distance from the breech?"
Milt, this might be a question Miller or other readers of Burrard or Gough Thomas may have an answer for. I thought Miller may have quoted a reference that touched on payload travel/time/pressure at one time long ago.

Burrard shows at least one time, pressure, velocity chart but is rather hard to decipher in the early stages. This was taken with the old 33 grain bulk "Smokeless Diamond" with a 33 grain charge (3 DE) & 1 1/16oz shot charge. He did not show the actual pressure rise but simply started it at the peak @ approx 1" from breech. Both time & velocity were showing a very near vertical rise at this point with time at about .0002 sec & vel about 100fps. Max pressure was 2.8 TonSqIn. By the 4" point pressure had fallen to about 2.5 ton, vel risen to about 750fps & time to about .0007 sec. 8 inchs pressure @ about 1.25 ton, vel @ 1000fps & time @ .0011 sec. In the 30" bbl velocith reached about 1285fps, pressure dropped to under .2 ton & time was just over .0026 sec.
I don't know just how this would apply to more modern powders but suspect would be very close to a powder having a medium burn rate, say on the order of Green Dot & similar.
PS; He also stated that upon the powder being ignited the initial pressure rise was on the order of 10,000 tons per second. Of course as the wads/shot begin to move, giving increasing volume, the rise slows, then peakes & starts to fall all in about that .0002 secs. This initial point is of utmost importance & shows why crimp strength can play a vital role in developed ballistics & also why the loaded shell length should never project into the cone, possibly delaying that initial opening. Things are happening "Very Fast".

It is worth looking back as to how the concern over shell length developed.In the era when rolled over shot wad was the method used for shell closure a loaded 2 3/4 shell measured 2 5/8 It normally contained 1 1/4 ozs, of shot and the appropriate powder charge.Likewise the 2 1/2 shell was 2 3/8 inches long it normally contained 1 1/8 ozs,of shot with a proportionally reduced powder charge. The chambers of the guns at this time were machined to correspond with expanded case length [2 1/2 or 2 3/4] At the same time, forcing cones were shorter in length than todays practice. In these circumstances it was absolute folly to attempt to shoot a 2 3/4 shell in a 2 1/2 chambered gun, always assuming you could force the action to close.
Most sportsmen of the day were well aware of the dangers presented by attempting to shoot 2 3/4 shells in 2 1/2 chambered guns , this concern has been passed down from father to son. Whislt this concern is still legitimate, the advent of the crimp closed case with its reduced case wall thickness and reduced closed length, has for all practical purposes eliminated the primary reason for barrel constriction caused by the shell case length. The remaining safety problem, one that has been repeatedly stressed by other comentators is control of breech pressure.," For your safety, use only shells that generate breech pressures within the allowable limits for 2 1/2 chambered guns!"

Thank you. I am simply trying to understand, to get a minds eye general understanding of what is taking place after ignition. I am sure we are all(well almost all) struggling with the concept of barrel bursting every time we see a picture of one. We all like our fingers and want to keep them intact.

I already have an understanding but each time I see a picture of a barrel burst I need to rethink it so I don't wake up in the middle of the night with a bad dream. Often in life there is one small piece of information that is missing in our knowledge base that causes things to go wrong. An example of this might be a stepped end of a chamber in a barrel designed for brass shells. Now, I have heard about this and I may even have a Parker that has it but I am not even sure if there is such a thing. Easy enough to find out before I shoot the Parker again but if you never heard of this kind of thing you would have no reason to even think about it or the safety issue that might develop. Clear as mud but I think you know what I am getting at.

Notable quotes;

"You don't know what you don't know" by an NTSB employee

"The only thing to fear is fear itself" by FDR

Maybe a balance of the two is a good place to be.

Builder;
Stepped chambers did indeed exist, & for paper shells also. I am not personally knowledgable as to whether or not Parker used then. Greener discussed them & stated shell lengths were not controlled close enough to provide the desired advantages & they left a stress point & also were hard to clean right at the point of the stress riser. They are most apt to be encountered on extremely old guns & any gun of this age should be given a through examination prior to firing with anything, even black. This is certainly not meant to imply they should never be fired, only to proceed with utmost caution. I would certinly think one of these guns chambered with a sharp step should never be used with shells having a longer than chamber fired length, even though they were shorter in their loaded length.

I suspect an 1879 Parker hammer underlifter G grade equivalent (I think) with .750 bore diameter that I was shooting with 2 1/2" shells. It has been in the safe for a while waiting for a cast of the chamber. Just have not gotten around to doing it. Too many things to do right now. It is all original and in very nice condition so it won't be changed but it seems important to find out for safety reasons. Thanks for the reply.

Milt

I have two 65mm chambered 16s. One of them weighs 5# 11 and I shoot reloaded light 2-5/8" 7/8 ounce and light 1 ounce factory loads in the gun. I don't see any difference in the fired shell relative to another gun with factory 2-3/4" chambers. I am considering lengthening the chambers in at least one of these so that I can feel better about using 1-1/8 ounce loads for pheasant.

These guns were purchased used and I'll bet they have been used a fair amount with 2-3/4" loads. Not everyone reloads or buys RSTs.

Recently there was a lengthy discussion of forcing cones and lengthening them. I believe that reaming a chamber has the potential to thin the barrels in the most dangerous place while lengthening forcing cones does not. That is not intended to imply that lengthened forcing cones have any real value. Are these guns from England? If so reaming the chambers invalidates the proof while forcing cones is a grey area. If they were my guns, I would not ream the chambers, but find suitable low pressure loads commercially even if they're 2 3/4.

I just found this thread that goes back over a decade, very informative debate.

I remember when this thread was active, and when I just reread it a thought came to mind that was not directly addressed. There are a number of 2.5” originally chambered guns that have had the chambers lengthened and reproofed in England. My thought is just because they have been reproofed for the longer chambers should modern 2.75” ammo be used? If pressure is the primary factor, are shooters mistaken in the notion that 2.75” chambers can accommodate modern ammo? Seems like if a gun was originally proofed at 2.5” with the associated pressures of that shell nothing has been done for the sake of safety, particularly when metal has been removed from in front of the chambers. I’m convinced low pressure in 2.75” shells is probably better than removing barrel wall even if the gun is reproofed. If the gun has had the chambers lengthened and been reproofed lower pressure ammo should still be used.

The Internet and forums on the Internet are not reliable sources for much valuable information. So I will add to that with my own experiences.

I used to visit with Bill Heckman when he had his shop in Livingston, Montana, about Damascus guns and how strong they were. He told me how they proofed guns and and I was amazed at how simple that process was. They put the gun in a brace and test it with their proof loads that are developed for proofing guns at a pressure above what the gun is actually designed for. II the gun didn't blow up, it was in proof.

I took several Damascus guns to him to get his opinion on shooting them with smokeless ammunition and what to expect. He told me that the good Damascus guns were as strong and even in some cases, stronger than the fluid steel barrels of the same era.

Since then, I have shot lots of older shotguns with Damascus barrels and had no issues at all. Before doing so, I did check to see they were in good working order with good wall thickness in the barrels and no rust or pitting.

I have shot plenty of 2 3/4 inch shells in my Webley SXS that has 2 1/2 inch chambers and had no ill effects at all. I do keep plenty of 2 1/2 and 2 inch shells around and shoot them exclusively in those shorter chambers as that is the best way to shoot them.

I have seen blown up shotguns that were from other reasons than 1/4 inch difference in shell length. The best rule of thumb is to shoot what you are comfortable with and if you are afraid of blowing your gun up, by all means use shorter shells.

I would also bet that the pressure is less likely to damage the gun as much as recoil would shake it loose.

shrapnel: IMHO there are many on this Forum with the bona fides to provide accurate and reliable information
Actual strength testing of pattern welded barrels
https://docs.google.com/document/d/1cvqRzkg0wEjhAAcFWr8gFi7aPFRsSIJ_hahfDxmrNAU/edit
and vintage steel barrels
https://docs.google.com/document/d/1dnRLZgcuHfx7uFOHvHCUGnGFiLiset-DTTEK8OtPYVA/edit

eeb:
John Brindle, author of Shotgun Shooting: Techniques & Technology published a review of Proof and Service pressures in Part 5 of his series in The Double Gun Journal, “Black Powder & Smokeless, Damascus & Steel”; Volume 5, Issue 3, 1994, “Some Modern Fallacies Part 5”, p. 11.
His estimated post-1954 but pre-CIP standard pressures by LUP converted to piezo transducer PSI

..............Standard Service.....Max. Service.....Proof
12g 2 1/2”.....6,800 psi..........8,800 psi..........12,250 psi
12g 2 3/4”.....7,800 psi..........9,800 psi..........14,050 psi

Great Britain adopted the 1969 Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives standards March 1, 1980 but continued using Lead Crushers to measure pressure until 1989.
The CIP transducer “Maximal Statistical Individual Pressure” is 850 BAR = 12,328 PSI for a “Maximal Average (Service) Pressure” of 740 BAR = 10,733 PSI, and “Mean Proof Pressure” of 930 BAR = 13,924 PSI.
900 BAR is for a “Maximal Average (Service) Pressure” of 780 BAR = 11,313 PSI and Proof pressure of 1020 BAR = 14,794 PSI.