The 380 ACP AMMO (9×17mm) (Automatic Colt Pistol) is a rimless, straight–walled pistol cartridge developed by firearms designer John Moses Browning. The cartridge headspaces on the mouth of the case.^[5] It was introduced in 1908 by Colt, for use in its new Colt Model 1908 pocket hammerless semi-automatic, and has been a popular self-defense cartridge ever since, seeing wide use in numerous handguns (typically smaller weapons).