I think it’s “Automatic Cartridge Pistol,” Tranq.
Never mind. I’m wrong.
http://www.myoan.net/shootingart/sm_pist_overview.html
That isn’t correct but not for the reason you think. Modern .38 caliber bullets do not measure .38". .38 special and .357 bullets are the same diameter, .357-.358" depending on bullet type as bullets made completely of lead are typically a thousandth of an inch bigger than those with a copper jacket.
9mm actually means what it says and bullets are typically .355-.356" in diameter. (9mm - 0.354") Some .38/357 revolvers are made to fire 9mm Parabellum ammunition with an alternage cylinder.
38 caliber used to mean .38" or thereabouts over a hundred years ago but not anymore. The first .38 caliber cartridges were used in converted cap and ball revolvers designed for .375" lead balls and these were called .36 caliber. Colt navy models were convereted to a .38 cartridge which used a “heeled” bullet design where the base of the bullet was smaller than the main body of the bullet. The small heel diameter fit inside the brass case and the larger diameter matched the outisde of the case.
When more modern guns were made the same brass cases were used but they used non-heeled bullets which were the same diameter as the heel on the old bullets. Barrels were of course changed to match the new bullets but for some reason they were still called .38s.
For somewhat similar reasons, having to do with the 1860 .44 caliber Henry rimfire rifle, modern .44 caliber is really .429"
Basicly its a handgun typically bought on saturday night. (Read cheap and plentiful.)
Used to be that a 32 could be bought at a pawn shop for a few dollars.
Used to be a guy would still have a few bucks in his pocket on saturday night.