1. Great detailed books are available for each major maker's guns...in these books, usually are schematics of how the maker's cut their chamber's and forcing cones, with dimensions...........the information age elctronically as well.....
2. Most older classics (pre 1930) had shorter, sharper forcing cones, as compared to modern shotguns, for ammunition of that day........so, if you do your homework and are looking at a classic gun, and you find long tapered forcing cones, it is likely the gun has been ground on.....
3. If the forcing cones have been ground up it is most likely someone altered the chokes as well......and possibly some honing also.....?
4. If the proper loads are shot, the older uncut guns shoot fabulous.....
All of which is great . . . except even when I asked the man who wrote a very good book on Ithacas, and who has access to the factory records, he couldn't tell me whether my 1920 Flues 12ga came from the factory with 2 3/4" chambers (which it now has) or 2 5/8" chambers. No problem at all spotting forcing cones that have been lengthened to the extent they typically are on modern shotguns. However, if you read the great, detailed book on Foxes, you'll learn that Savage supposedly lengthened all chambers to 2 3/4" (which would have required some cone alteration as well, although not as long as they're done today) whenever a short-chambered gun was returned to the factory for any work. The cones on the Flues I referred to above certainly have not been lengthened to modern preferences, but that doesn't mean the chambers might not have been lengthened and the cones done a few decades back, when shorter cones were still the style.
Chambers and cones are on one end of the barrels, chokes on the other. I've had a lot of chokes altered on older guns; far fewer chambers and cones. Why would the reverse not be equally true, assuming the guy having the tampering done liked the chokes as they were, but wanted altered chambers and/or cones? If you can find standard bore dimensions for the old classics and have a bore and choke gauge, it's not too hard to detect honing.
If the old guns shot tight with older, pre-WWII shotshells, chances are they'll shoot tighter with modern shells. That's great, if that's what you want. But you may be looking for different results, if your goal is to maybe shoot a turkey and some trap with your 16ga Parker as opposed to using it for skeet, as well as grouse and woodcock. Different chokes for different folks, to paraphrase a bit.
