This is a question that has bothered me for some time. Most Cartridges have names that at least are close to there barrel bore or grove diameter. Say the 45-70 which uses a barrel of .450 bore diameter and .458 grove diameter. Or the 7mm Mauser which uses a .284" (7mm) grove diameter.
I am not talking about small changes of a thousandth or two, too differentiate it from an other cartridge. Or minor changes in diameter due to manufacturing tolerances or slightly larger lead bullets.
What puzzles me are some of the cartridges for which are way off in name. Take for example the fallowing. 32 S&W = .312" grove diameter, 38 special = .357" grove diameter, and the 44 mag or special = .423" grove diameter.
I can only assume that this is due to something in the switch from mussel loading to cartridges but have no idea why.
Does anyone know the story here?