doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com 2.75" shells in 2.5" chambers

Can you post the muzzle velocities of any of these cited circumstances?? Did Fergus report the MV's of the shells fired in guns having different cones?? If the increased pressure resulted in an increase to the MV of the load, then there is an obvious reason for an increase in recoil. IF on the other hand the increased pressure was a result of a retardation of the opening of the crimp &/or the movenment of the charge & no increase in MV occured, then no increase in recoil occured. If, with no other data, we accept that he reliably reported an increase in recoil, then we "Must" of necessity asume the end ballistics of the load were also altered. I have no problem accepting this. If, however you are promoting that this rise of pressure, increased the recoil without an acompaning increse in the discharge velocity of the charge, then I have an "Extremely Great" problem in it's acceptance.
Pressure moves both the charge & the gun. Resistance to movement results in an increase in pressure. When only weight of either gun or charge is entered into the equation the movement is directly proportional to those weights. Any other factor I am aware of which can be entered into the equation which give a resistence to movement applies equally to both gun & charge. Thus no change of the movement of one can occur without an equal change of the movement of the other.
The only part of this entire diatribe still even really open to debate is just how much change in the rate of acceration of that movement is required for an average shooter to detect it. This I feel will remain un-answered until we have some very reliable accelerometer data coupled with "Extensive" input from a large number of "Unprejudiced" shooters, done under conditions which prevent "Preconceived" ideas affecting that input.
Less there be any misunderstanding due to various statements attributed to Burrard, I will state I have had the "American" edition of his works which combined the three volumes & appendixes into two books for some 40+ years. I have over these 40+ years referenced them extensively. "IF" Burrard ever attributed any factor to recoil other than; Wt of total charge (IE shot, wads & powder), Discharge velocity of that charge, VS weight of the Gun I would love to "Re-Read" it as I have totally forgotten it. Volume; Chapter & Page "PLEASE".

"Jim, if you don't believe that an increase of 1500 psi and blown ends on shells might also result in an increase in recoil, why don't you try it for yourself and see? Sort of in Bell's "Finding Out For Myself" mode. Personally, I am more than willing to accept the reports from Thomas and Fergus that long shells fired in short chambers with short cones produced similar visible results to the ends of the shells; so why is it unlikely that they also produced similar increases in pressure? And in both cases, they reported significantly increased recoil. And in Fergus' case, he fired the same long shells in another gun, also with short chambers but with longer forcing cones, with totally different results: no blown ends on the hulls, no noticeable increase in recoil. He also reported that true 2 1/2" hulls worked fine in the gun with the short cones."

An increase in pressure of 1500 psi MIGHT increase velocity and therefore increase recoil. BUT, the increase in recoil WILL be because of the increased velocity, NOT because of the increase in pressure.
And NO, I don't believe blowing the ends off of shells will increase recoil.
I'm amazed at the lengths you pressure believers will go to prove that pressure CAUSES recoil. It does not! rates of accelleration and all the other smokescreens offered are just smokescreens. Recoil is caused by the gun's reaction to the velocity of the ejecta, period. Learn to live with it. Facts are facts. Physics is physics. BS and speculation are just BS and speculation.
You might as well say the primer causes recoil because without it, there would be no burning of powder and expanding gases to cause the velocity of the ejecta. Or maybe it's the trigger's fault.

I think your average 6lb shotgun firing 1 oz. loads at 1200fps recoils at a velocity a bit over 12 fps. I didn't even have to take off my shoes for that one! Probably should put one on rails and time it.

jack

Miller, I can't tell you where to look in your copy of Burrard. I have only an extract, and he addresses the effects of compressing the hull in the cone about 5 paragraphs into his discussion entitled "Length of Cartridge": "If the mouth of the cartridge is compressed by being held in the chamber cone, the resistance to the initial movement of the shot charge will be greater and the pressure will be increased." Well, we know from the Bell test (cited earlier) that there was a significant increase in pressure when a hull extended well into a forcing cone. If that "squeezing" effect initially retards the acceleration, with the greater pressure building behind it, does it not make sense that the acceleration--once the "obstacle" (case mouth) is removed--will be greater? And could that not explain an accompanying increase in recoil?

You are correct in stating that neither Burrard nor Thomas nor Fergus give velocity figures. However, both Thomas and Fergus report the same visual evidence (blown case mouths) that Bell reported, when he also reported a significant pressure jump. Or are you doubting three separate reports of blown ends on cases? And if, in the case of Thomas and Fergus, they report the same visual evidence, why is it not possible that they also experienced significant increases in recoil? Just because they didn't measure velocity does not mean that it did not increase. Or, the increased recoil may have been due to the change in acceleration when the charge was finally released, with greater accompanying pressure.

Fergus describes his experience with British shells "approved for use in 2 1/2" guns" in a pre-1900 Westley Richards and in a Jeffery (also 2 1/2") from the 1930's. (The Westley, by the way, was stamped as having passed reproof some time after 1954.) In the former, blown end and "stiff recoil that caused me to stop and examime the discharged cartridge". Yet the gun performed fine with true 2 1/2" hulls.

Thomas is well aware of the same situation and comes to the same conclusion: On some guns with "exceptionally abrupt" cones, "the use of the longer case may give rise to objectionable, or at least enhanced, pressures." Same thing Burrard says, using very slightly different words--Burrard referring to the compression of the case mouth. (But how else is that going to happen, except in the forcing cone???) Thomas also verifies that the gun in question works fine with true 2 1/2" shells, whereas "with 2 3/4" cases, though designed for 2 1/2" chambers, it recoils unduly and makes his arm numb." And the crimps are blown off.

We already know that the pressure increase is real. All the authorities agree, and Bell's tests prove it--significantly so, when the case extends well into the forcing cone. We also know that the blown ends are real: Bell, Thomas and Fergus all report the same evidence. Bell was using a pressure gun, so he couldn't comment on recoil. Nor did he report velocity, other than to say--for all the tests he conducted--that "velocity of all loads remained essentially the same", without additional specifics. (I would've liked to see the velocity on that 3"er with the blown ends and the big pressure spike.) So perhaps the difference in acceleration resulted in the increased recoil--which, given that the other two pieces of evidence (pressure increase and blown ends) are measurable or observable, I believe really did increase. Why doubt the third effect when we know for certain that the other two happened, and they're being reported by the same people?

But hey, if you guys want, go ahead and continue telling people that any 2 3/4" hull loaded to the appropriate pressure will work just fine in any gun with a 2 1/2" chamber, regardless of differences in cone length and angle. For that matter, while you're at it, tell them to disregard it when they blow the ends off the hulls. And if they feel increased recoil . . . well, it's all in their heads.

Larry;
I have definately not made any such atatements as that & "YOU" JOLLY WELL KNOW IT!!!
I in fact made the statement "IF" I fired a shell in a gun & the result was torn case mouths I "WOULD STOP IMMEDIATELY" & it did not matter "IF" it had excessive recoil "OR NOT". I have also on several occasions even stated I would not fire shells whose loaded length extended into the cone. I have been generally Fru-Fraued for this, but have stood by it. Neither Thomas or Bell to my knowledge addressed this situation, but Burrard did. Also note I "Have Never" advised anyone to ignore an increased recoil.
Now here is a quote you made back on page 9.

Note by the word "AND", as well as You put the excessive recoil "First", this would be quite easy to interpret that one could ignore the torn case "If" they did not get excessive recoil. This is simply not the case & I will continue to warn people that it is indeed possible for conditions to exist which can create an excessive max chamber pressure without increasing the velocity & recoil of the gun. Your continuos use of the terms Stiff, Vicious, Excessive, Brutal etc can quite easily leave the impression on a reader that if they put a load in their gun & fire it & don't "Get their Teeth Kicked Out" they can go merrily on their way & have no fear for themselves or their gun. Now Larry you are a noted Gun Writer & held in high esteem by many (Myself included in all I have read of yours "Other than Ballistics"). You need to be extremely careful here as you can quite easily lead someone into trouble by seemingly indicating it is inevitable that an increase in max pressure "Will Always" result in an increased recoil. An increase in velocity & recoil will indicate an increase of the total average pressure under the curve, but this is altogether different than max pressure. Max chamber pressure is not a "Direct Indicator" of either Velocity or Recoil. While this is strictly speaking a shotgun board, these principals apply equally to Pistol, Revolver & Rifle. Many guns have been Wrecked over the years without the shooter ever feeling an excess recoil.

Good catch, Miller. I should have said "If you're getting significantly increased recoil and/or blowing the ends off shells . . . " Goes to show you that all of us can use help from sharp readers (or editors who understand the subject).

That being said, I don't think the issue addressed by Fergus and Thomas has anything to do with the loaded length of the shell extending into the cone. Unfortunately, the only unfired Brit shells I have at present are true 2 1/2". However, I have a fired 67MM Game Bore 16ga, and it is exactly the same length as a fired Remington 16ga Game Load. Both crimped, so it seems to me their unfired length would also have to be the same. And while I agree with you that an unfired shell extending into the cone should be avoided (that's almost certainly what happened when Bell touched off a 3" shell in a 2 1/2" chamber), the only way that could be the issue in the cases reported by Fergus and Thomas is if the guns in question (in which the ends were blown and sharper recoil reported) had chambers shorter than 2 1/2". We know that the 67MM shells, which the Brits say right on the shell boxes are approved for use in guns with 2 1/2" chambers, do in fact function just fine in MOST guns with 2 1/2" chambers. So my strong inclination is to agree with Thomas and Fergus that the culprit is the length and taper of the forcing cone, not the length of the chamber--although it would be interesting to measure the chambers on those guns in which problems have been reported, then do the same with other 2 1/2" guns that handle the same shells with no problems.

I suppose it could be that Brit gunmakers prior to 1900--like some of their American counterparts a few decades later--were intentionally short-chambering their "2 1/2" guns, and for the same reason: in order to get improved patterns. That'd work fine as long as the shells were true 2 1/2", but might indeed result in the unfired shell extending into the cone if the chamber were somewhat shorter than 2 1/2". Haven't ever read anything indicating the Brits adopted that practice, but since some American gunmakers did, I guess you never know.

Miller, Jim and Larry, Chuck, and others,
All of you bring up great points and a lot of your knowledge about this subject. For me it is a little too deep. I reload low pressure, low velocity shells in 2 1/2" and 2 3/4" for some old L.C. Smiths I have. Mostly because I have the time to do it and because of the loads I want. None were ever tested by me, but all the loads were from either tests done by Tom Armburst for the 16 ga Reloaders Group or form reloading guides.
I don't shoot 2 3/4" shells in 2 1/2" chambered guns, why, because I don't feel it is safe. I'm positively sure that previous owners of the 20 ga "elsies" and 16 ga "elsies" I have had 2 3/4" shells through them, why, because ignorance is bliss. Most people that buy older guns have no idea what the chamber length is and just shoot todays modern loads designed for heavier payloads. This is why a lot of the L.C. Smiths we see have cracks behind the sideplates. This was especially true from the 50's-80's when we didn't have the selection of shells we have now. Shells then were loaded Magnum or Maz loads and people just used them, and I'm sure they noticed the recoil.

I believe Jagermeister stated a good statement, people think 2 1/2" shells mean low pressure-low velocity, why would it, it's just a shorter shell.

Also firing a 3" shell in a 2 1/2" chamber, idiotic for one and even though it was a test and nothing happened, you can't tell me recoil wasn't greater. First of all the 3" shell had more powder and more payload of shot than a 2 1/2" shell.

JayCee, your picture of the blown barrel, I don't reload black powder but the difference between the two powders is probably 3-1, so he used approximately 100 grains of smokeless, talk about excess, he's lucky.

AH Fox HE Becker bored 2 3/4" chambers, after abundant 3" magnum loads. Courtesy of David Trevallion.





Suspect the recoil was a tad...uh...brisk

Besides the gun flying open, and after messing his pants I wonder if that had anything to to with.......pressure?

When most of us speak of pressure, we're speaking of the "spike" and the peak pressure produced. Peak pressure certainly has very little correlation with ballistics or recoil. Pipes mentions pressure "under the curve". I'd think you could average the plot for sustained pressure over time and that psi number would be the same for all powders and powder charges producing the same ballistics for a given payload. I continue to think that the time to "peak" is bound by necessity to the inertia of the payload.

jack