doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Chambers lengthened from 2 1/2" to 2 3/4"

I am looking at British box lock for sale. It is proofed at 1 1/8 oz. Nice gun, however somewhere in time, someone lengthened the chambers from 2 1/2" to 2 3/4". It's here in the States, not in England. It appears to have adequate wall thickness (.040") and tight bores (.023").
Would you:
Pass on the gun because it is out of proof,
Expect a significant discount on the asking price, how much?
Buy it anyway and shoot 2 1/2" RST shells and enjoy it.

4. Have someone with the interest, equipment and expertise carefully measure the wall thickness at the end of the chambers and at the forcing cones before purchase.

If barrel wall thickness at end of the extended chamber is adequate, I would buy it anyway at some price. Proof would only matter if sold in the UK with little bearing at all in the US. But that's just my opinion...Geo

From my understanding, part of the definition of "Proof" involves the guns bore dimensions. When was the gun originally proofed?

If the chambers were opened in the USA and the gun not returned to UK for re-proof, it would be out of proof...Geo

Definitely have it checked at the forcing cones - my in proof damascus barreled light weight Birmingham BLNE with original 2.5 inch chambers is only about 90-100 thousandths thick at the forcing cones. I am comfortable with that with suitable loads. Extending the chambers would significantly affect wall thickness in that area.

As others have stated; Have that guns barrels measured for thickness.
Have a read of a thread here, now on page 3, about shooting 2 3/4 shells in 2 1/2 chambers. I consider the little lengthening of the chamber to be as safe as what is being recommended in that thread. If not over reamed in the chamber or overly cut in the forcing cones or had a heap big honing of pits done to it then only little metal has been removed. Measure chambers, measure forcing cones, measure bore, measure barrel wall thickness.
I personally own & shoot a 12g British hammer gun with 1 1/8 Oz proof & chambers lengthened from 2 1/2 to 2 3/4. Now out of proof.
In respect for the guns original proof shot weight & the lengthened chambers I load & shoot 1 Oz low pressure loads for it & have no problems. One ounce is actually a nice shooting load & frugal on powder & shot whilst still getting the job done in this light game gun of mine.
If I want to shoot high, long, heavy, hard, & loud I have other guns with that capability & use them. One friend named one of them, "The Master Blaster" & another friend named another one "The Howitzer"
O.M