Action Short recoil operation [ 1 ] Muzzle velocity 825 ft/s (251 m/s) Feed system 7-round standard detachable box magazine [ 1 ] The M1911 is a single-action , semi-automatic , magazine-fed, recoil-operated handgun chambered for the .45 ACP cartridge , [ 1 ] which served as the standard-issue side arm for the United States