Very good questions. When Tony Galazan designed his chamber gauge set, it was based upon modern bore and depth dimensions. Parkers have been measured exhaustively by people assuming their guns have been honed, or otherwise altered, but in actuality, they've been found to vary significantly; especially bores. 729" may be considered gospel today. but many (older) guns have actual bores approaching the high .740"s. I had a stone new grade 4 'lifter that measured .750". These variations will have an impact on where the chamber gauge bottoms out.
As to why an Olin Kodensha gun appears short may be due to the theory that the shell, opening up within the forcing cone (firmly believed by Parker) gave a better gas seal. Long and the short of it is, people have been shooting 2 3/4" ammo in guns with 2 5/8" chambers for a hundred + years and guns digest them just fine. Today, we have to concern ourselves more with keeping the velocities down because of the age of the wood.
|