The Colt M1911 self-loading pistol began life as a design study during the early years of the 20th century and was only accepted into US service after the most rigorous testing and careful selection. In design the M1911 was a recoil-operated automatic pistol derived from the Browning patents of the early 1900s in which the barrel was unlocked from the slide by a swinging link, and relocked by the same link on recoil.
Whilst quite heavy for a handgun (2.5 lb unloaded) the M1911 was nonetheless well balanced and incredibly tough. It was able to resist dirt and mud well and could be relied upon to perform adequately even when old, loose and sloppy. It fitted well into the firer’s hand and pointed easily but did suffer from a rather hefty kick on firing. The standard issue bullet being the heavy 230 grain .45 Colt ACP held in a seven round magazine.
In World War I, unfortunately, there were too few of these guns available to meet entirely the needs of the American Expeditionary Force in France. Many Americans instead carrying a variety of weapons, mainly revolvers, with the Colt 45 and Smith and Wesson M1917 (re-chambered to accept the rimless Colt 45 ACP round) being produced in substantial numbers to meet government contracts.
In 1923 the Springfield Armory commenced work on an improved model which was standardized as the M1911A1 in 1926. The reworked weapon(which main outward differnce to the earlier model was in the the use of a grip safety) would go on to become the U.S. Army's standard sidearm throughout World War II and beyond. Between 1937 and 1945 over 19 million M1911A1 pistols were manufactured, not only by Colt, but also by Ithaca and Remington.
The M1911A1 was a semi-automatic with the seven round magazine in the handgrip. All the user needed to do to fire was to pull the trigger each time he wanted to fire, the next round being automatically placed in the chamber as the spent cartridge case was ejected. The M1911A1 had three safety devices; a grip safety on the handle, the safety lock, and the half cock position on the hammer. The fore sight was of the fixed blade type and the rear sight consisted of a fixed groove.
Like most weapons, it was not perfect. It was considered to be quite heavy and had a significant recoil. Nevertheless it remained in service with the U.S. Army until 1985, when, finally it was superseded by the 9 mm M9 Beretta Double-Action.
Sources
Pistols 1914-18 (John Weeks, Article in War Monthly magazine)
The US War Machine (Salamander, 1978)
