The chamber should have a definite ending. This is the ledge the chamber length guage sit on also. An older gun can have had many things done to it, some may not have been such a great idea. That said I have seen older single shot shotguns with no chamber at all! They simply had tapered bores that allowed the maker to dispense with chambering and choking. The barrel if cut at a certain length was a modified another length produced another constriction. The gentleman who owned this old gun(a 20 guage) was using 3 inch shells for turkeys. I assumed he was in danger but an old friend assured me there was no need for concern. He may have lessened the gun life span but I suppose all shooting would do that. I always hate to make guesses but it is possible that someone in the past was a little heavy handed with the polishing tools and has blurred the chamber s definition. I would certainly take this gun to a competant smith for a check up. This kind of thing can lead to thinning of the barrels to a dangerous degree. I would not shoot this gun until checked and approved..
