Miller, I don't know much about the other gun manufactures, and if some of them back then were overboring for black powder, I can only go from bore readings I have taken on L.C. Smiths from 1884-present. What I have found is that most were ,725-.730, and most of the early hammer from Hunter Arms were .725.
My Skeet's gage only reads to 12 1/2" and from the breech most were bored so, funny thing is going from muzzle down 12 1/2", past choke area, most read .720 and some slightly lower. This is true for both hammer and hammerless. I'm wondering if this is what L.C. Smith Maker and Hunter Arms referred to as "Multiplied Choke Boring" for better patterns.
I had read somewhere that 12 ga. bores were .729 -.002 +.000. I couldn't find it in both of Brophy's books, but I'm sure it is in there. I know that in his "L.C. Smith Shotguns" he lists on one page the bores, and the 12 ga. as now being .732. Also listed is the 16 ga. as .662, so this had to be in the 1930's when the change was from .650 to .662.
I was taught that if it was a three decimal reading the tolerances were +/- .005 unless noted. I do see in some, the tolerances were + .000 -.002.
How well their quality control was, who knows.
