The M1911 pistol origins go back to the late 1890s, resulting from the need to replace a variety of revolvers in service at the time with a reliable self-loading pistol. This single-action, semi-automatic, magazine-fed, recoil-operated pistol chambered in .45 ACP was subsequently designed by John Browning. It went on to serve as the standard-issue sidearm for the United States Armed Forces from 1911 to 1985 with over 2.7 million built. Widely copied by nearly every firearms manufacturer in the world, this style and operating system became the preeminent handgun type of the 20th century and of nearly all modern centerfire pistols. Used by 28 countries and in every war since World War I, there are now millions more in use by civilians, with many variants, calibers, and modifications in circulation. The M1911 has truly become the defining handgun of the modern age, and has nothing short of a cult following among enthusiasts world-wide.