The M1911 is a single-action, semi-automatic, magazine-fed, recoil-operated handgun chambered for the .45 ACP cartridge, which served as the standard-issue side arm for the United States armed forces from 1911 to 1985. The M1911 pistol originated in the late 1890s as the result of a search for a suitable self-loading (or semi-automatic) handgun to replace the variety of revolvers then in service.