Colt 1911, also known as the M1911 pistol, is a semi-automatic pistol which served as the standard-issue sidearm for the United States armed forces from 1911 to 1985. It was widely used in World War I, World War II, the Korean War, and the Vietnam War. Colt 1911 is chambered for the .45 ACP round. Designed in 1911, this pistol is one of the weapons with longest service history in modern times, as it is still carried by some U.S. forces.