doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Impact of opening 2 1/2" chambers to 2 3/4"?

I have a Churchill SXS made about 1896 with original, presumably Whitworth steel barrels. The barrels have two sets of proof marks, the most recent marked as .729, 2 1/2", 3 tons, nitro proof. Wall thickness is good. The chambers have been opened to 2 3/4".

Are there any safety issues in shooting a gun that has had its chambers opened up and what 2 3/4" loads might be safe to shoot in it, but from a safety standpoint, and the standpoint of not wanting to damage the gun? Thanks.

Most of us here sing the "Swing Low Sweet Pressure Loads" song when we shoot old guns. david

The safety issue I'd be concerned about would be how much metal is left in the walls around the new front end of the chambers. Even if there is plenty, I'd surely stick with low pressure loads, as David suggested.

Kent TM 2 1/2-inch No. 5 will kill anything out to 40 yards.

Check out the B & P low pressure shells. They have sub-sonic loads and the Competition 2000 7/8 and 1 oz loads which are great as well as 2 1/2" shells in various pressure loads. David

Why not just sell it and buy another gun that does not require it to be opened up?

If you care about such things, the gun is no longer in proof.

I always worry about what type of loads they put through them and how many of those loads. You know 2 3/4" shells went through gun, you just dont know how hot they were. Many on this site might suggest the damage if not to barrels or action could be more to wood.

Or the danger to the shooter or bystander.

I'm assuming from your post that there's no 2 3/4" (or 70MM) mark at all on the barrel flats, which would indicate the chambers were opened at the time of its modern, 3 ton reproof.

If that is the case, take it to someone with expertise in English guns. Have them measure barrel wall thickness, and in particular have them measure thickness immediately in front of the lengthened chamber. I seem to recall that the figure I've seen for minimum thickness at that point is .100"; elsewhere on the barrels, I'd hope for a minimum of .025" or better--but let the gunsmith provide his expert advice.

If you shoot the gun at targets and reload, there are all kinds of 12ga formulas that will get you down in the 5-7,000 psi range, using standard 2 3/4" hulls, which is plenty safe with that gun, assuming the barrels are OK. RST's MaxiLites are also very nice, light 1 oz loads for targets and light game. For heavier hunting purposes, both Kent Gamebore and Eley make some very nice 1 1/16 oz field loads. In spite of the fact that your gun has 2 3/4" chambers, you should avoid all American factory 2 3/4" shells. The pressure will be excessive for a gun proofed at 3 tons.

Don't forget the AA Featerlites, their pressure used to be posted here on the site, somewhere ... & it was 7,000 PSI.

After you have the barrels inspected and if they are safe consider what high pressure loads will do to the stock. It is likely that the stock will crack if the barrels hold up to the stiffer loads. The wood is 100 years old after all and made for the lower pressure loads. Why bother with high pressure loads anyways? Both low pressure factory and reloaded ammo is very easy to come by these days. Better safe than sorry and one restock job will make you sorry. Cracks suck.

The AA Featherlight loads are now the AA 'Low noise Low recoil'; 15/16 oz at 980 fps and run 6,200 psi.

If the gun has been lengthened to 2 3/4 without having been subjected to re-proof it is out-of-proof an will be illegal to sell in the UK (which may not matter to you but may be a useful reminder to those considering purchase of such a gun).

Then it depends on what the lob has been done like.

The advice re-low pressure loads is sound. Factory loaded 2 3/4" shells are generally loaded to a pressure -safety expectation of 3 1/4 tons per square inch.

As the "Latest" proof stated .729", 2½", 3 Tons Nitro it is obvious the chambers were opened after that proof & thus are technically "Out of Proof". Pressure as such will be of most concern as to what the bbl will take. The stock will be more affected by total load than by pressure per se. You can find loads that will push a 1½oz load with slow powders at pressures lower than a real fast powder would push a 1oz load to a similar velocity. The heavier load is going to be more punishing to the stock (as well as your shoulder) even though having a lower pressure.

Featherlites . . . the problem with them (other than their extremely low velocity, which might make them OK for targets but not for hunting) is that I've heard a bunch of them go "poof" on the range when the temperature is down around freezing.