The Colt SP1 is the original civilian AR-15, produced from 1964 onward as the first commercially available semi-automatic version of the ArmaLite AR-15 design. Features a 20-inch barrel, triangular handguard, slab-side lower receiver without a forward assist, and three-prong flash hider. The SP1 is the founding document of the civilian AR-15 market — every subsequent AR-15 traces directly to this model. Type: Rifle Action: Semi-Automatic Caliber: 5.56 NATO Capacity: 20 Year introduced: 1964, USA Weight: 6.35 oz Overall length: 39" Status: Discontinued Intended use: Sport Shooting, Collecting