The M1911A1 is the refined military service version of John Browning's iconic .45 ACP pistol, incorporating improvements from WWI service experience: arched mainspring housing, shorter trigger, relieved frame behind the trigger, extended grip safety spur, and simplified checkering. The standard US military sidearm from 1924 through 1985. Type: Pistol Action: Semi-Automatic Caliber: .45 ACP Capacity: 7 Year introduced: 1924, USA Weight: 38.5 oz Overall length: 8.25" Status: Discontinued Military use: Yes Intended use: Military