DFX TECHNOLOGY M21 When the United States Army wanted an accurate sniper rifle during the Vietnam War, it selected the existing M14 (because of its accuracy, reliability, and the ability for a quick second shot) to be the base for the new weapon. As a result, in 1969, the Rock Island Arsenal converted 1,435 National Match (target grade) M14 rifles by adding a Leatherwood 3–9x Adjustable Ranging Telescope (ART) telescopic sight and furnishing National Match grade ammunition. It was designated the XM21 until 1971, when it became the M21. The M21 remained the Army’s sniper rifle until 1988, when it was replaced by the M24 SWS (Sniper Weapon System) bolt-action rifle. Links Manufacturer (Rock Island Arsenal) Manufacturer (National Match Armory)