m1911 pistol

Army and Weapons | M1911 Pistol | The M1911 Semi-Automatic Pistol is a single action short recoil-operated semi-automatic pistol, chambered in .45 ACP. It features a 7 round magazine and has an effective range of approximately 50 meters. The M1911 produced by Colt was the standard sidearm of the U.S. military from 1911 to 1985.  The history of the Colt M1911 began in early 1900s, when famous designer John M. Browning began to develop semi-automatic pistols for Colt's Patent Firearms Manufacturing Company. In 1905, Browning designed two .45 cal. semi-automatic pistols in response to government interest in a higher-caliber sidearm to replace the standard-issue .38 cal. 

Revolvers then in use (primarily the Colt M1892). The two designs were hammer and hammerless versions of the same basic design and show a clear resemblance to the M1911. In 1906-1907 the U.S. military tested several semi-automatic pistols including designs from Colt, Luger, Savage, and others. These weapons were deemed unsatisfactory for military use and the competitors were asked to improve their designs in anticipation of new trials in 1910. The Colt Model 1905 remained a popular civilian pistol. 

However, Browning and Colt spent the next three years engineering improvements to the Model 1905. In 1911, after further extensive testing, the new pistol and its cartridge were adopted for U.S. military service as the M1911. Prior to and during World War I, more than one million of these guns were manufactured by Colt, Springfield Armory, Remington UMC, Burroughs, Savage, and others.  The rights to manufacture Colt/Browning design were also sold to some foreign countries, such as Norway and Argentina.  The M1911 is a short-recoil operated, locked breech, semi-automatic pistol. It has a single action trigger with a frame-mounted safety that locks the hammer and slide. The hammer can be locked by the manual safety in the cocked position only. An additional "grip" safety is incorporated into the rear of the grip that locks the trigger when the gun is not held in the hand properly.

 

The barrel and slide are interlocked via lugs on the upper part of the barrel, just ahead of the chamber. After firing, the barrel and slide recoil for a short distance, before the rear part of the barrel is lowered by a tilting link that separates the barrel from the slide. The slide continues back, extracting and ejecting the spent case, compressing a recoil spring located under the barrel, and cocking the hammer. The recoil spring then returns the slide and barrel to battery, chambering a new round on the way back. When the magazine is empty, the magazine follower activates the slide stop, locking the slide in the open (rear) position. The gun is fed from a single stack, seven-round magazine. The magazine release button is located on the left side of the frame, just behind the trigger guard.

8 round magazines are also available for the M1911, and some variants offer "double-stack" magazines that hold 14 rounds. Recoil operation is based on the law of conservation of momentum (Newton's Third Law, commonly paraphrased as "every action has an equal but opposite reaction"). In a recoil-operated firearm such as the M1911, the momentum of the projectile traveling forward out of the barrel is balanced by an equivalent recoil force acting on the barrel/slide assembly in the rearward direction. 

A recoil-operated self-loading firearm depends on proper "tuning" of the projectile's momentum (its mass multiplied by its velocity) so that there is sufficient recoil force generated to perform the extraction, ejection, and chambering of the next round. Optimal operation of a standard M1911 occurs with the use of .45 ACP ammunition weighing 230 grains traveling at approximately 250 meters/second. 

Modern Gov't/1911 variants may differ, more or less, from this description: some guns may have widebody frames that can accept dual stack, high capacity magazines; frames could be made from steel, aluminum alloys or polymer; some could have Double Action or even Double Action Only triggers, ambidextrous safety switches and slide stops, and other modifications. There are compact variants of the M1911, and variants of the M1911 that are different calibers; 9x19mm Parabellum variants are fairly common. The Colt Delta Elite is a M1911 modified to accept the 10mm Auto cartridge.