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

I know this subject has been beat to death, but I need it to be beat a bit more. I read that early manufacturers liked to shoot 2 5/8" shells in 2.5" chambers because they felt it gave a better seal and performance. I have also heard that 2.75" shells in 2.5" chambers can dangerously increase pressures and tear the edge of the shell off, while I have also read that the increase in pressure by doing so is not all that much, say 500 psi +/-. There's a lot of conflicting info out there. Bottom line: would a 7k psi low pressure 2.75" shell be dangerous in a 2.5" chamber Lefever? I am reloading 2.5" shells anyway, but I would like to know if I can shoot some of the shells I already have.

Bottom line for my pea brain Mark:
Will it increase pressure? (assuming the opened case mouth does NOT extend into the forcing cone) Maybe alittle.
Will it increase recoil? Likely and possibly alot.

Why in the world put your gun's 100 year old stock wood (and your rapidly aging shoulder and cervical spine) through the abuse when 2.5" shells are now readily available?

Why would it increase recoil and what do you mean ''alot''?

I'm thinking paper hulls would increase pressure more (because of being thicker) than a plastic hull would.

Pressure has nothing to do with recoil.

Using 2 3/4 low pressure shells in a 2 1/2 chamber will result in only a very moderate increase in pressure.

You can safely shoot your Lefever using those loads as long as the gun is in good shape.

Pete

I'm going to shoot some 2 & 3/4 Federal Vintage shells (advertised at 5000 psi) out of my 2 & 1/2" Scott hammer gun shortly if the rain holds off.

GJZ: I can personally testify that the recoil in my less than 6# 1928 20g Trojan with chambers 2 7/16" using factory 2 3/4" Win AA 7/8 oz. target loads was absolutely brutal, and obvious to everyone observing on the skeet field. The perceived recoil with 1 oz. 2 3/4" 1150 fps. 16g loads in my 2 9/16" chambered 6 1/2# LC 16g was clearly less after lengthening the chambers. 1 oz. 2 3/4" target loads in my 2 1/2" chambered No. 2 frame 12g Trojan weighing 7 3/4# felt no different than 1 oz. 2 1/2" shells.
But my anecdotal data may not apply to other's experience, as I have a terrible flinch and am very recoil sensitive.

"Bottom line: would a 7k psi low pressure 2.75" shell be dangerous in a 2.5" chamber Lefever? I am reloading 2.5" shells anyway, but I would like to know if I can shoot some of the shells I already have. "

Bottom line is, no one can tell you.
There are many opinions and in some cases back of the barn tests but as an Engineer I use the correct shells for the gun I am shooting.
It's really up to you and at your own risk.-Dick

Just my recollection of Bell's article, but I thought he said he tested paper hulls as well and they didn't show an increased pressure outside of the average of the plastic hulls. Also, my memory says that he got between 0 and 15% increased pressure from 2 3/4" shells in a 2 1/2" very short (1/2"???) forcing cone chamber.

My personal experience with only one load in a couple damascus guns is that my 2 3/4" Federal paper hull loaded to what a manual says should be mid 7K psi is actually coming out to mid 6K psi measured in a short chamber. I feel no significant recoil and velocities are super consistant at 1150 fps.

So, from all the above I've formed the opinion that short chambers (mainly 2 9/16 to 2 5/8" in American guns as I understand it) is not a reason to change my reloader setup to load 2 1/2" shells. It's inconvenient to change to shorter shells and I see no benefit at this time. However, if someone has convincing evidence that my information is wrong, I'm always willing to change that opinion.

I do have to take exception to the statement that pressure has nothing to do with recoil. I believe it is one of several key components in acceleration of the payload in a gun, the others being time and weight of the payload, and surface area of the payload upon which the pressure and time work to accelerate the payload and conversely, the gun in the opposite direction. I'm no physicist or ballistician, but I think that covers the basic physics of a gun. Sorry Pete.

We played with exactly that scenario this past weekend My 2 daughters, my son and I, ran through about 600 16 bore loads in 3 different doubles, a Stevens, a Cz and a "G" Lefever. We shot short shells in one bbl and LP handloads in the other, a number of times. All shooters tried the test. Which recoiled more? The short shells...in all guns.We all agreed on that. I dont know what chamber length my Lefever has. The load I am using is 1 oz shot, SG16 wads in both Fiochi and Federal/estate 2 3/4" plastic hulls.......pressure supposed to be under 7k, velocity 1220 fps...Non Scientific eval..FWIW