The M1911 (also known as Colt 1911, or Colt Government) is a single-action, semi-automatic, magazine-fed, recoil-operated pistol chambered for the .45 ACP cartridge. The pistol's formal designation as of 1940 was Automatic Pistol, Caliber .45, M1911 for the original model of 1911 or Automatic Pistol, Caliber .45, M1911A1 for the M1911A1, which was adopted in 1924. The designation changed to Pistol, Caliber .45, Automatic, M1911A1 in the Vietnam War era. Designed by John Browning, the M1911 is the best-known of his designs to use the short recoil principle in its basic design. The pistol was widely copied, and this operating system rose to become the preeminent type of the 20th century and of nearly all modern centerfire pistols. It is popular with civilian shooters in competitive events such as USPSA, IDPA, International Practical Shooting Confederation, and bullseye shooting. Compact variants are popular civilian concealed carry weapons in the U.S. because of the design's relatively slim width and the stopping power[
