The M21 is the sniper variant of the M14, accurized by the Army Marksmanship Unit with a match barrel, walnut stock, and Leatherwood ART II scope. Served as the primary US Army sniper rifle until replaced by the M24 SWS in 1988. Type: Semi-Auto Rifle Action: Gas-Operated Caliber: 7.62x51mm Capacity: 20 Year introduced: 1969, USA Weight: 9.8 oz Overall length: 44.3" Status: Discontinued Military use: Yes Intended use: Military, Precision, Sniper, Collector