The 25 ACP, or 25 Auto, cartridge was originally designed by John Browning of Browning Ammunition in 1905. Browning designed the round for blowback pistols lacking a breech lock mechanism, designing it to also duplicate the performance of the popular 22 Long Rifle cartridge when being fired from a 2 inch barrel. The small 25 caliber round was actually the smallest case Browning could implement that would still have the room for a primer pocket. Today, although the 25 ACP round was initially intended for semi-automatic pistols, multiple manufacturers have designed and produced various 25 ACP revolvers, making the 25 ACP round more versatile.
