Ive always noted on this Board and elsewhere that chambers increase to the standard lengths they are today right around 1925 to 1926. I havent encountered a double built in the thirties that has the smaller chamber. Not saying there isnt one but by then I would think hes safe. But if you are going to buy old guns buy yourself some way to measure the chamber. Theyre real easy to find and I agree with Doug, I wouldnt change that gun at all not one in that condition.