doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com No RST at the Southern this year

Damn Putin, it's all his fault!
All kidding aside, they just emailed out a flyer informing us about limited shotgun ammo for the upcoming Southern Side by Side event this year. I know I have had issues finding 2 1/2" shells, but have picked up a few boxes from some friends.
One friend I have said that lengthening the chambers ever so slightly to 2 5/8" will not make the gun out of proof.
Recommend or not recommend?

If the gun has sufficient metal around the chamber there is no reason not to shoot 2 3/4” ammo in it as it is without changing anything. But if you’re uncomfortable with that send the gun out and have the forcing cones lengthened to 1” or 1 1/2”. Accomplishes almost the same thing as chamber lengthening without removing as much metal in a critical area. Not sure about the English proof law but not relevant on this side of ocean.

It is too bad, but should come as no surprise to anyone. Let's hope this shortage ends sometime soon

English proof laws don’t apply here. I’d shoot as is with low pressure 2 3/4” loads or reload.

Is your friend a European trained gunsmith? Is he familiar with English and European proof, did he measure the walls, note the original proof dimensions, account for any honing of the bores, examine the chamber and forcing cone area with magnification, inspect for corrosion under the ribs? Is the gun in proof, now?

Asking for a friend.

Best,
Ted

as to lengthening chambers to 2 3/4... its about barrel wall thickness in front of chambers...generally speaking, if after lengthening chambers, you still have .090 in front of chambers, you should be ok for safe shooting with light loads...might as well have forcing cones done as well...

always seek professional help...

and be aware that any alteration to a gun may reduce its resale value...

What Ted said.
ANY chamber/forcing cone alteration is considered by the British Proof House to take a gun out of proof.
Joe is correct regarding forcing cone lengthening; slightly increase volume within the chamber/cones = slightly decreased pressure. At least Bell's study (WITH 12G - we have NO data for 16 and 20g) suggested such.
I would not lengthen the chambers of a lightweight British game gun, of any gauge, and would do so with caution (and only by an expert) if a U.S. maker's 16 or 20g.

So as an interesting aside to this discussion I thought I would mention a lovely Purdey that recently came through the shop. In very high condition and built as a 2&1/2" gamegun that was ordered in the late 20's, never collected by the chap who ordered it and remained in stock until the the US Naval attaché was dispatched to London in the early '40's who then purchased the gun. The gun had its chambers lengthened to 2&5/8" and the proof marks defaced but the gun was NOT re-proofed. Purdey verified that the chambers had been lengthened before the sale. I do not believe a 2&5/8" proof length was ever a standard. While I generally agree that lengthening chambers on British guns takes them out of proof, I am a bit uncertain as to how 2&5/8" chambers fit in the equation.

Pretty sure altering even the choke takes a gun out of proof in Olde ‘Blighty, and pressure is way lower out there than in the chamber area.

Might be safe to alter a bore, but, you are going to nick gun value by altering anything in the bore on an English gun.

Best,
Ted

Certainly choke tubes take a gun out of proof, I do not believe opening chokes does but I could be wrong.