doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Turn-of-the-century shotshell pressures

We are fortunate today to have an abundance of turn-of-the-century pressure data, which can be found here
https://docs.google.com/document/d/1F2sQuPm05IE4VWYYnCkvuXmYEzQoWd_SQgaAfUOZEFU/edit

I stumbled upon another interesting source; “Shotgun Ballistics”, Charles Askins, Outdoor Life, July 1917
https://archive.org/details/sim_outdoor-life_1917-07_40_1/page/76/mode/2up

Pressure X 2240 converted to PSI (not Burrard's formula and I am confident that is how DuPont did it), which requires adding 10-14% for modern piezo transducer numbers.

Note modern SAAMI standards allow +/- 90 FPS and +/- 900 PSI = .4 Long Tons

12g 2 3/4” 1 1/8 oz.
……...…………...3 Dram…..3 1/4…..3 1/2…..3 3/4…....4
DuPont Bulk…...7,750……7,840….8,019…..9,744….10,640 PSI
“Schultz” Bulk…8,064……8,960….9,520…..9,878….9,744 PSI



16g 2 7/8” 1 oz.
………...……….2 1/2 Dram…..2 3/4…....3…....….3 1/8..…..3 1/4
DuPont Bulk….7,683…….....8,243..…9,223......9,811…..10,080 PSI
“Schultze”…….8,333…………9,677..…10,461..…12,790..…11,200 PSI



20g 2 7/8” 7/8 oz.
………….…...…..2 1/4 Dram…2 1/2…....2 3/4…..3
DuPont Bulk……10,685…..…12,208..…12,902…14,538 PSI
“Schultze”………11,715...…12,499…..12,858…13,530 PSI

Note the maximum pressure observed for the standard 7/8 oz. 2 1/2 Dram “Schultze” load was 13,978 PSI + 10-14% is approaching proof load pressure at > 15,500 PSI

Thank you for posting this! The black powder pressures in comparison to the Smokeless are interesting considering, I assume, quite a few older guns would have been fielded using the "new" loads. I know my one uncle used a Damascus barreled Baker 12 gauge up until he died in 1986, his shell of choice was the Winchester Super X 1&1/4 ounce loads. I don't know the pressure of those shells and that may have changed since? The gun was choked full in both barrels. Thanks again.

Now if we could only get current shotshell companies to cough up their pressures?

Serbus,

Raimey
rse

liverwort:
The 1928 edition of “Smokeless Shotgun Powders” by Wallace Coxe, ballistic engineer of the Burnside Laboratory of the E.I. du Pont de Nemours & Co. reported 3 1/2 Dram Eq. 1 1/4 oz. loads:
NOTE: pressures were measured by crushers (LUP) and modern transducer measurement pressures would be 10 – 14% higher
DuPont Bulk smokeless powder - 11,700 psi
Schultze Bulk smokeless powder - 11,800 psi
28 grains of Ballistite Dense smokeless powder - 12,600 psi
(Note all 3 are greater than the SAAMI 12g 2 3/4” recommended maximum pressure of 11,500 psi)
40 grains of DuPont Oval Progressive Burning powder used in the Super-X loads - 9,400 psi

There is a Hunter Arms Co. Pressure Curve dated June 10, 1929, from the McCracken Research Library, Buffalo Bill Center of the West (found by Gary Rennles) very likely from DuPont
http://library.centerofthewest.org/cdm/singleitem/collection/WRAC/id/8149/rec/107
12g 3” ‘Record’ 1 3/8 oz. shot presumed 1275 – 1295 fps = 13,250 psi
12g 2 3/4” Super-X ‘Field’ 1 1/4 oz. shot presumed 1330 fps = 10,750 psi
12g 2 3/4” 1 1/4 oz. 28 gr. (Dense) Ballistite = 12,900 psi
12g 2 3/4” 1 1/4 oz. 3 1/2 Drams DuPont Bulk = 10,000 psi
+ 10-14%

I suspect they prefer to be vague about pressure to allow for lot to lot variances in pressure, all the way up to SAAMI maximum. The only guys who care about pressure, are us, and we won’t be around forever.

Best,
Ted

Pretty simple to send 5 to Tom Armbrust to determine the pressure(s). 'Twould be nice to get chamber pressures for free from the shotshell manufacturers but, peace of mind is worth far more than Tom's fee, sometimes.

Which, will tell you the average pressure of five rounds from THAT LOT. The next lot, or the lot produced just before, may have different components and/or powder, and may test completely differently, and as long as they do not exceed SAAMI max, will be considered by the producer to be compliant. If anything at all changed, the pressure can be assumed to be different. But, you have no way of knowing how or which way different, much less what components were changed.

I don’t actually have a dog in this fight, but, we do have to consider US production ammunition suspect, from the standpoint of pressure, unless it is specifically stated on the package.

Best,
Ted

Agreed, Ted. But, isn't it still better than the current alternative?

No.

If you are a guy shooting one of those guns with .018 wall thickness, 9” from the breech, (or, actually having a dog in that fight) you really have to know what your pressure is. Every time. Yes, there were guns produced with tubes that thin that are in proof. None are mine, however. Too big a feet for that in my world.

The last lot you had tested, is not the same lot they are loading. They are different. That is why they have different lot numbers. Simple as that. SAAMI framework allows for a wide variation of pressures to be sold. The guy with an auto or pump doesn’t know, or, need to know pressure.

Old double gun guys, different deal. I probably should not have posted “US produced” ammunition, above, rather, I should have typed “SAAMI Compliant ammunition”. I have no idea if SAAMI spec ammunition is produced outside the US, or, if it will be, someday.



Best,
Ted

Ted, there IS no way to know your pressure everytime, even with RSTs or handloads. Variations in wad seating pressure, powder drop, crimping, even hull to hull plastic elasticity all will affect pressures. The best low pressure reloads that can be turned out have variations in pressure, sometimes significant. I have proven that with loads sent to Tom for testing. But, by having them tested you CAN get your loads within an acceptable range, or determine if factory loads are within an acceptable range. B & P Comp One loads are claimed to be in the 8000 psi range, by the manufacturer. Tom's testing for me has proven that to be true.

I accept pressures in the 8000 range as fine for my Foxes, Parkers, and other vintage guns, even sound Damascus. You may believe differently, and that's fine, but no way do I believe the variation, lot to lot, of this load will yield pressures that get close to SAAMI max, or enough to be a problem.

I don't shoot guns with barrel walls as thin as .018", there's too many fish in the sea. My point in advocating pressure testing of factory loads, to satisfy one person's curiosity, was/is not to try to find some factory loads that can be used in a .018" MWT barrel. You misunderstood my intent, obviously. My wife says I often do not make myself clear on a subject. Perhaps .......

P.S. Tom's testing data shows you more than the AVERAGE pressure for 5 loads, it shows you EACH load's pressure, and the standard deviation, high, and low pressures are determined from that. Much more information on the data sheet than just average pressure for the five loads.

Pretty sure anything B&P is a CIP load, Stan. Anything CIP is going to be more consistent on pressure, and OK to use in any gun that remains in proof, even twist or Damascus. SAAMI, not so much. It will be at or under SAAMI max. That is about all you will know. That is by design, by the way. It give the manufacturers great leeway in how and what they use to load ammunition.

I agree with your number for old guns, but, I suspect that getting that number, consistently, with factory loaded ammunition that makes no claim to being anything but SAAMI compliant is a tough thing to do. The boutique ammo guys can and do make it. But, expecting to get it off a shelf at the local mart from run to run is perhaps a bridge too far, even with testing a few from time to time.

My oldest gun has steel barrels with .060 wall, 9” from the breech. I was always suspect of thin walls, but, it was more of a worry of denting them, for me. Somebody right here posted the results of testing on about half a dozen, older, 20 gauge factory promo loads that were right up against SAAMI max a few seasons past. That, was sobering to me, and, changed how I think about old doubles and ammunition. Pressure is the bugaboo.

Be well, Stan.

Best,
Ted

Ted, that barrel looks like something was lodged in the bore, not high pressure. High pressure loads have the chamber opened up, not the bore. Now, if the reason for your post was to show a gun with very thin walls, that's a little different. But then who in their right mind would shoot a gun with .018 barrel wall thickness 9" from the breech ? That's not a over pressure question, but one of sanity.

There exist English 12 bore guns proofed at .018 wall. If the correct ammunition is used, no big deal. Unless you are me, and bang the thing into a tree taking a leak in the woods.

A man has just got to know his limitations.

I posted the blown up American gun as it doesn’t seem to have excessive wall thickness.

Best,
Ted

Do you have first hand knowledge of the reason it blew up ? I've always been lead to believe that a gun blown up in the chamber is from over pressure, one blown up down the barrel is an obstruction in the barrel. I'm not trying to start an argument, but just thought a gun blown up from an obstruction maybe shouldn't be shown in a discussion about over pressures.

Thin barrels do split

Perazzi MX2000 inexpertly "backbored" to a wall thickness of .012"



Honed to .739" with resultant wall thickness .018". I do not know the load which caused the split

I’ll bet that was exciting.

Not as exciting as this Tom. 1st shot with 12g 2 3/4" Bismuth Magnum Game Load 1 3/8 oz. Unfortunately, I don't have the wall thickness measurements or the pressure of that load

I shoot doubles with walls as thin as .018-.020 on a fairly regular basis. I am very strict about what loads I use and keep the pressures down to sane levels, 8,000 psi for 20 and 5,000-6,500 psi for 12's. The important thing to know is where are they thin and what your real pressure is on the load you want to use. Barrels at .020 are more likely to dent than blow up with sane loads. Thin barrels 20" from the breach do not scare me but anything less than that or closer than tat will need careful consideration before I shoot them. Very careful.

Preacher, why do you post stuff like this???


And you also post stuff like this below, concerning your one-and only Damascus barreled OE Grade L.C. Smith 16 gauge gun...


You can get pissed at me for pointing out the obvious, and I'm sure you will be blinded by personal animus in your response. But it sounds like KYJon feels the essentially same way about guns like your one-and-only Damascus barreled OE Grade L.C. Smith. And he was commenting about barrels that are not only thicker than yours, but also have that .018" to .020" wall thickness a full 6" further from the breech than your gun.


It is little wonder that your friend Ed is repeatedly questioning everyone about what barrel wall thicknesses they consider safe, and why they feel that way. Nobody here, who has any good sense whatsoever, would advise someone to buy or shoot a ratty old Damascus L.C. Smith O Grade that has barrels with an .016" wall thickness at 14" from the breech. If you really wish to pass yourself off as a copy-and-paste internet shotgun barrel expert, then you really need to stop posting flawed and conflicting data, and potentially dangerous advise.

That would be only two reasons barrels ever blow up, and it would leave out barrels honed too thin, and loads too hot used in those thin tubes. I also saw a Darne that had a crease dent in the barrel, that the GI importer tried to remove with a Peter’s high brass load that resulted in a very neat split exactly where the crease was. Undented, the Darne would have been up to any factory 16 gauge load the fool could have stuffed into it.

Best,
Ted

ah don git hit...

if you know the barrels are thin...

why shoot guns with barrels so thin...

why take the risk...

Some people actually know what they are doing, ed. Don’t trouble yourself with it.

Best,
Ted

so hits bout ego den...

"here, hold mah beer while ah show youse how hits done"

Found another DuPont ballistic table
Clearly the c. 1920's published pressures as significantly higher than the c. 1900 pressures. Some can be explained by different powders, and it may be that by 1920 the DuPont Brandywine Experimental Station testing was more accurate

Capt. Charles Askins and E.M. Sweeley, “Patterns, Velocities, Ballistics”, May 1921 Outdoor Life
https://archive.org/details/sim_outdoor-life_1921-05_47_5/page/300/mode/2up

DuPont Bulk Smokeless
Numbers require adding 10 - 14% for modern piezo transducer pressures.



12 gauge 1 1/8 oz. in 2 3/4” Winchester Leader hull
3 Dram = 7,616 psi.....Max. 9,565 psi
3 1/4 Dr. = 7,840 psi

16 gauge 1 oz. in 2 7/8” hull
2 1/2 Dram = 7,683 psi.....Max. 8,176 psi
2 3/4 Dr. = 8,243 psi
3 Dr. = 9,363 psi

20 gauge 7/8 oz. in 2 7/8” hull
2 1/4 Dram = 10,550 psi.....Max. 11,715 psi
2 1/2 Dr. = 12,208 psi.....Max. 13,285 psi
2 3/4 Dr. = 12,902 psi.....Max. 14,022 psi + 10-14% - WOW!

June, 1922 Outdoor Life
https://archive.org/details/sim_outdoor-life_1922-06_49_6/page/414/mode/2up

12 gauge with DuPont Bulk Smokeless. + 10 - 14% for transducer numbers. No. 6 shot (the standard)
1 oz.
2 3/4 Dr. Eq. = 5,958 psi
3 Dr. Eq. = 7,190

1 1/8 oz.
2 3/4 Dr. Eq. = 6,944 psi
3 Dr. Eq. = 7,840
3 1/4 Dr. Eq. = 8,758 psi

1 1/4 oz.
3 Dr. Eq. = 8,602 psi
3 1/4 Dr. Eq. = 9,610 psi
3 1/2 Dr. Eq. = 10,595 psi
3 3/4 Dr. Eq. = 11,581 psi

Once again: Excellent information, Doc Drew!

That right there got my attention! I shoot a number of "restored" vintage American doubles I've never had wall thickness confirmed for. I try to shoot low pressure loads, but there are those times people have handed me "whatever" shells so I could continue a hunt.

Those of us who are Flatwater veterans will recall a modern Spanish 28ga on which one barrel blew. That's after having passed modern Spanish proof. Somehow bored with a thin spot of (IIRC) .014". Taking part of the shooter's hand with it. So even having passed modern proof is not necessarily a 100% guarantee.

July, 1922 Outdoor Life
https://archive.org/details/sim_outdoor-life_1922-07_50_1/page/48/mode/2up
16 gauge with DuPont Bulk. Plus 10 - 14%
7/8 oz.
2 1/2 Dr. Eq. = 7,325 psi
2 3/4 Dr. Eq. = 7,728 psi
1 oz.
2 1/2 Dr. Eq. = 7,930 psi
2 3/4 Dr. Eq. = 8,400 psi
1 1/8 oz.
3 Dr. Eq. = 11,670 psi


August, 1922 Outdoor Life
https://archive.org/details/sim_outdoor-life_1922-08_50_2/page/120/mode/2up
20 gauge with DuPont Bulk. Plus 10 - 14%
7/8 oz.
2 1/4 Dr. Eq. = 10,550 psi
2 1/2 Dr. Eq. = 11,715 psi
1 oz.
2 1/4 Dr. Eq. = 12,029 psi
2 1/2 Dr. Eq. = 13,373 psi or about 14,750 psi by transducers

28 gauge Plus 10 - 14%
5/8 oz. 2 Dr. Eq. = 8,714 psi
3/4 oz. 2 Dr. Eq. = 10,259 psi
3/4 oz. 2 1/8 Dr. Eq. = 10,998 psi
7/8 oz. 2 Dr. Eq. = 12,387 psi

Standard loads from Outdoor Life Sept. 1922



Note the standard trap load was still 1 1/4 oz.

In 1913 the Interstate Association submitted a poll to trapshooters:
Are you in favor of restricting loads for target shooting to 3 Drams Bulk, or the equivalent in Dense powder, and 1 1/8 oz. of shot?
Frank Butler – “Let me say that the shooter can break targets with a three dram one and one-eighth load if he holds right. Harold Money, who traveled as a professional for years, always used three Drams “Schultze” Powder and one and one-eighth shot.”
https://books.google.com/books?id=fZBBAQAAMAAJ&pg=RA5-PA10&lpg

DuPont began an advertising campaign promoting 3 Dram loads in 1914

In 1919 the Executive Committee of the American Trapshooting Association voted on whether to establish the standard load a 1 1/8 oz. 3 Dr. Eq. The proposal failed.
Arms and The Man, August 2, 1919
https://books.google.com/books?id=TBofKvr1Fi4C&pg=PA377&lpg

It was not until April 1940 that the ATA disallowed 1 1/4 ounce loads.

Thanks, Doc.

The testing by Capt C. Askins and Sweeley, along with De Pont progressive powder and help
from John Olin at Western Cartridge; eventually resulted in some powerful Super-X shells.
The research eventually culminated in 3 in magnum shells and the AH Fox HE Grade Super Fox along
with the LC Smith Long Range shotguns.

The wall thickness and pressure-related incidents are sobering. Particularly as relating to our 100-yr old
fine American fluid steel barreled shotguns. Has anyone or any company done steel metal fatigue testing in older shotguns?
Thanks for the research, DH.

New or vintage shotgun barrels, made with the appropriate steel that is free of defects, do not "fatigue" unless stressed above the yield strength, by loads for which they were not designed, obstruction, or corrosion/pitting.

We have published data from the gun makers regarding yield and tensile strength, and a good collection of actual testing for vintage pattern welded, decarbonized and fluid steel barrels
https://docs.google.com/document/d/1cvqRzkg0wEjhAAcFWr8gFi7aPFRsSIJ_hahfDxmrNAU/edit
https://docs.google.com/document/d/1dnRLZgcuHfx7uFOHvHCUGnGFiLiset-DTTEK8OtPYVA/edit

Drew;

I have often thought about, but do not know, what happens to the structure of the material of shotgun barrels when they are stressed above the yield strength. Would you be so kind as to discuss what the effects of such stress does to the metal as well as the future life of the barrels after they have seen such stress above the yield strength.

Kindest Regards;
Stephen Howell

I'm not a metallurgical or mechanical engineer, and only know what those that are tell me, and what I've learned from reading.

The non-deep thinkin' non-expert version:
Cleavage occurs when the pressure exceeds the ultimate (tensile) strength of the steel.
Low cycle fatigue occurs when the pressure exceeds the yield strength (or elastic limit; the stress which gives a permanent deformation of 0.2%) and it has a characteristic micrographic appearance described as "wave in the sand" or "beach marks".
The barrel wall stretches (elastic deformation) with each pressure event (shot) until cleavage occurs. The number of cycles required for cleavage depend on the pressure, steel yield strength and ductility (% elongation), and wall thickness...and no doubt a lot of other things I don't understand.
The wall of a barrel that ruptures from an obstruction will of course "stretch" until cleavage (with a characteristic "ring bulge"), and this is not low cycle fatigue.

600X Scanning Electron Micrograph