doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Short chambers and recoil?

None of the complicated formulas have anything to do with my test. It dealt with PERCIEVED recoil as reported by shooters who didn't know which barrell had a lengthened cone.

There was no statistical difference. If you think you gun will kick less after you lengthen the cones, you have a preconcieved notion that will affect your perception. Happens all the time.

When I ran the NC Civilian rifle team I had a shooter I was using in the National Trophy Match who had a bad day before the match. He was certain the barrel in his M14 was going bad. An All Guard Coach who was helping me showed me how to me correct the problem.

We took the gun and shooter to the repair trailer having advised the armorer what we were doing. The armorer told the shooter he'd found a big problem and had corrected it. The next day, the confident shooter shot better than he had in months and talked the rest of the trip about how his gun had been going south for weeks. The coach and I just looked at each other and grinned.

Wonky,
I don't see several as an unfortunate thing in either case.

Best,
Ted

Good job, 2-p. Very well explained.

Chamber length has nothing to do with recoil, so unless the short chamber produces more velocity, it will not produce more recoil. Beside that, "more recoil than what"? Unless you lengthen the same chamber, in the same gun, and use the same shells, what would be you comparing it to?

I think there is a horsefly in the yogurt on your explanation as well, Jim. If one has a short chamber gun, and uses 2 3/4" ammunition, only to discover the cases ripped off down to the contact length at the cones, velocity will not automatically increase-but, recoil will. I suspect pressure would, also, but, I can't prove it.
A friend owns a French Charlin that rips the cases down to a bit below 2 1/2", sometimes even with European spec 65mm ammunition. To say the gun is unpleasant to shoot is an understatement.

Best
Ted

Your statement doesn't prove anything, either. There would obviously be SOME increase in pressure and likely some increase in velocity(if it's ripping the cases off). You don't say what length your imaginary chambers are but if your example even exists, they would probably have to be 2", in order to "rip off the 2-3/4" shell "down to the contact length at the cones". Ripping off part of a case that extends past the cone, into the bore is believable, not barely into the cone. Of course, you don't say what the chamber length of your friend's Charlin is, and more importantly, how much it weighs. I'll bet it is a very light gun. Ask him to lengthen the chambers and report back if the "unpleasant shooting" becomes pleasant. Maybe he's putting the shells too far into the chambers, resulting in the Gough Thomas recoil syndrome.
Best to you, as well

Why would recoil automatically increase? If pressure goes up, acceleration of the shot load will also go up. This would tend in the direction of higher MV, but, I agree, not automatically assure it. The pressure spike will increase powder burn rate and might cause burn-out enough early to result in similar MV's.

My thinking is the effort it takes to uniformly rip the end off a case, in the direction of the shot, would have an equal and opposite effect going the other direction-toward the shooters shoulder. More recoil being the result. The effort expended by the cartridge powder charge to rip the end off may or may not increase velocity, but, I'm guessing not, since more "work", has been done, the work of ripping the case mouth off. Even if it it undesirable work, it costs energy. The expenditure of more energy in this example is more likely to cost velocity, inspite of higher pressure.
My opinion, proven nowhere I know of.
Unless you can think of a reason for this not to be true, I'll run with it, based solely on the one example of a gun that I've seen that does it.

Open to any theories you may have, however.

The gun in question has 65 stamped on the tubes, but, a 16 gauge chamber tool from Brownell's stops a good 1/4" prior to the 2 1/2" mark. Monday morning gun at the proof house, maybe? It is well used, so, someone isn't/wasn't sensitive to recoil. Owner doesn't hunt or shoot it, just a collector. Nothing will be altered on this gun, by him.

Best,
Ted

Charles Fergus reported something along these lines with two Brit guns he owned. Both 2 1/2", one late 19th century with short, sharply angled cones; the other 1930's with longer cones. 2 1/2" shells were fine in both. However, the longer Brit ammo (67.5 MM, I think) loaded for use in 2 1/2" guns resulted in the ends blown off the cases and increased recoil in the older gun; no problems in the newer one. Don't know whether those shells were getting past the cones on the older gun, but something was causing very different results in one compared to the other.

If I remember correctly the gun Fergus reported on was a very early gun which essentially had "No Cone" but a step at chamber. It could have been cut with something like a 45° angle rather than being absolutely square, but this would still be essentially not a forcing cone as such. In such case the longer shell would indeed open into the "Bore" of the gun.
As to more Work producing more recoil, if one placed a fitted solid steel plug into the forcing cone which effectively blocked the bore & totally prevented the crimp even opening at all or any movement of the charge enough "Work" would be performed to "Rip Open" the chamber walls but no recoil would occur because nothing moved.
Anything which "Retards" the movement of the shot, friction etc, produces a "Forward" push on the gun equal to the retardation of the charge. This is the reason "Pressure" is not a factor in recoil formulas. Recoil is the result of the gun moving in an opposite direction to the charge.
One more time, Anything which "Retards" the movement of one "Retards" the opposite movement of the other. Mr Jim Legg's statement is absolutely true, any "Anecdota" statements notwithstanding. Any statement of increased recoil without accurate velocity checks is totally "Worthless"