doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com 2 1/2" chambers and 1" cones

WTS, nobody in his right mind would suggest using modern (think SAAMI standard) 2 3/4" loads in a 2 1/2" chamber. The learning has been, and remains, that low pressure loads in 2 3/4" hulls have minimal pressure increase in a 2 1/2" chamber, especially with a known 1" cone. If you are not sure of a load's pressure, don't shoot it. If you have any doubts, order Vintager type 2 1/2" loads. However, for maximum economy and convenience, roll your own using loading manual low pressure loads in compression formed 2 3/4" hulls.

There are all kinds of good reasons to reload 2 3/4" hulls for 2 1/2" guns. To start with, the very conservative Brits have been shooting 2 3/4" shells (loaded to the appropriate pressures) in 2 1/2" guns for a very long time. Both Burrard and Thomas refer to the practice as being quite safe--although they can be quoted out of context saying otherwise.

Economics are, of course, a prime consideration if you're going to shoot a lot with an older shotgun. There are very good 12ga hulls available for reloading, better (and cheaper, starting with factory ammo) than the factory 2 1/2" stuff.

With the exception of light loads made by RST and Polywad, a lot of the 2 1/2" shells out there are field loads, not target loads. You can work up 2 3/4" reloads with far lower pressures and far less recoil. So depending on which short shells you select, you can easily be better off with your own reloads.

The reason people used to pay attention and use "the right shell in the right gun" is that there were all kinds of short loads readily available--both target and field--in both short and long hulls. Looking at my 1940 Shooter's Bible, there were roughly twice as many 12ga factory loads availabe in 2 5/8" as there were in 2 3/4" back then--which meant you could get them anywhere. Far more trouble finding short shells today, and the only way to get any sort of real selection is to order them.

And the importance of using the right shell in the right gun, back then, speaking of factory ammo: different pressure standards for the short vs the long shells. Made lots of sense, if you were getting your ammo off the shelf--as it still does today.

As for marking short chambers, Wonko . . . how many American guns have you seen with short chambers "marked"? I can't recall having seen a single 12ga factory marked 2 5/8", nor a 16ga marked 2 9/16". As a general rule, I don't believe American shotgun makers started marking chamber lengths until they converted to a pretty much uniform standard of 2 3/4". My advice to those looking at vintage American guns is that if it's NOT marked 2 3/4", then chances are very good the chambers are short--or were, when the gun left the factory.

Thanks Larry....you saved me alot of typing. You hit all the points. Nice job.

I have in my possesion some 2.5" shells (Italian mfg. and loaded to CIP standards) that recoil more than my 3" Kent Faststeel duck loads. My 2 3/4", 1 oz. and 7/8 oz. loads are below 5500 psi and the payload leaves the barrels going 1150 fps. Easy on the guns action, the stock and more importantly...ME.

Bell & Armbrust have proven time and time again that there is no danger in using 2 3/4" shells in 2 1/2" chamber. Read up.

Dustin

There is actually only one 'right' method to check long cases in short chambers. Just load lead caliber slug in long case and fire it through your gun with short chambers. If fired case, its throat looks not good or broken, these particular cases are not suitable for this gun.
Actually I don't care about peak pressures, light or hot loads and Sherman Bell article, but if cases throat is damaged or broken after slug firing, I'd suggest to stay away from these cases or cut them to right length.

Correct Geno.....!.....

If you fire 2.75" hulls in a 2.5" chamber & forcing cones that have not been "butchered" it will usually exit the chamber with the star crimp still partially closed...visible in your hand.....and the modern plastic wads will strip off plastic while passing through the forcing cones with the 2.75" star crimps folded partially out into the cones, thus leaving plastic residue in the barrels..........

2.5" hulls will open properly and will not strip plastic while passing the forcing cones because the star petals are completely open and laying flat in the chamber.....as they are supposed to.......

All the old 2.5" chamber guns were made when roll crimped paper shells were in vogue........as an example:---if you shot a fiber wad, roll crimped paper hull of 2.75" length in a 2.5" chamber it would open flat and create no problems........roll crimped paper, not plastic star crimp...........again the key words are "un-butchered cones and chambers"....i.e. original factory short chambers and cones........these 2.5" chambers deserve 2.5" hulls, plastic or paper, rolled or star crimped.....loaded to whatever suits your needs............IMO..........

Interestingly enough, prior to the advent of plastic shells and wads, there were quite a few "experts" who advocated the use of longer hulls in short chambers. The result, as evidenced in various tests, was improved patterns. Reason: the paper hull, opening into the cone, provided some protection for the shot on its initial contact with the barrel (since it was not contained in a plastic wad).

From my own experience, which is fairly extensive in terms of firing 2 3/4" standard crimped shells in both 12ga and 16ga guns with short chambers and "unbutchered" cones, I can't say I've noticed that the crimp is any more "partially closed" than it is when fired in a 2 3/4" chamber. And the author of the article on long shells in short chambers in "The American Rifleman" back in the 30's showed graphic photographic evidence that 2 3/4" paper shells, fired in 2 1/2" chambers, did indeed show evidence of contact with the shot charge: "Viewing, in Figure 2, those shells that have been shot in short chambers and as a consequence are tapered on the ends and have the paper cut by the shot to a thin edge . . . " A.P. Curtis, "Advantages of Short Shotgun Chambers", The American Rifleman, July 1936. Curtis thought this an advantage, as mentioned above. But it does not exactly leave the shell "open flat".

For several years, I had a pair of British 12ga boxlocks with unaltered 2 1/2" chambers and forcing cones. I shot thousands of 2 3/4" shells (loaded to appropriately low pressure) through those guns. Cleaning them revealed no evidence of excess plastic fouling. Bores came out nice and shiny with the same combination of Hoppe's 9 followed by a light coat of gun oil that I used on my modern guns.

To the best of my understanding from the beginning of the fold/star crimp in the late 30's british shells sold 7 marked for use in "2½" chambered guns were all longer than the chambers. This was done for a two-fold reason. The new crimp resulted in a shorter overall length of the loaded shell which reduced the internal volume resulting in a shorter less effficient wad column unless the "Fired" length of the hull was lengthened giving a similar "Loaded" length to the older roll crimped load. Also it was feared the shorter loaded length of the new crimp would make the shells appear to be of a 2" length & be used in these lighter wt guns with possible disastous results.

The OD of a shotgun bbl normally tapers at a more rapid rate than the chamber body itself, but not as rapid as the forcing cone. There are few bbls existing in which a thinner wall would be produced than that of the end of the chamber by lengthening the cone unless it were carried to some extreme length. Moving the chamber end forward will result in a thinner wall. This is why some proof laws require re-proof for a lengthened chamber, but not for a lengthened cone.

Just personally I would not fire even that first shell loaded with a slug or other solid projectile from a bbl in which I knew the hull length was longer than the chamber. This presents an altogether different circumstance than firing a load of shot which can flow through the slight reduction of diameter. I would likewise not fire a shell which had a loaded length long enough to reach into & engage the cone prior to firing.

Have ever try buckshots? It will be the same like with slugs or worth even.
I remember Collath' double 16g 2.5" (btw, bores were marked 16) broke half of plastic 2.75" shell and buckshot flew away like solid slug. Kick was significant.

What would shooting that slug or buck shot do to the end of your barrels if you tried pushing it thru, oh lets say say a .040 choke or tighter?

I think I'll keep on doing what I've been doing for years with absolutely ZERO problems, shooting light recoiling, low pressure 70mm shells in 65mm chambers. I own a few guns with short cones, I shoot them often and I usually get around 10 to 15 reloads out of a single Remmy STS hull, when the hull starts crackin at the mouth (crimp area), its because I shot it to death, not because of the short cone. Do what ya'll want to do, at the same time I'll be doing what most other people are doing who've read the published material and have put many thousands of rounds down range with ZERO problems.

Dustin

I think I will keep doing what I've been doing for over 50 years with ZERO problems........2.5" hulls in 2.5" guns.......

Tried 2.75" Nitro Gold Rems once and after no more than 5 loadings they were cracked and burnt junk with 7/8 oz. light loads........

I have been shooting 2.5" hulls ALSO in 2.75" LC Smiths with over 20 reloads per hull.......that's all the proof I need........and I shoot every day............

Do what you want............takes all kinds to make a world..!..!..!..