The M1911 is a single-action, recoil-operated pistol chambered for .45 ACP. Designed in 1911 by John Browning, the M1911 is the best-known of his designs that use the short recoil design. It was widely copied with its operation system later becoming the preeminent type of the 20th century and a majority of all modern centerfire pistols. The M1911 served as the standard-issue sidearm for the United States Armed Forces from 1911 to 1985.