History and specifications of the M21 SWS sniper rifle, which has been upgraded from the M14 combat rifle for sniper purposes

  The M21 SWS (Sniper Weapon System) is a semi-automatic sniper rifle that has been used by the US military and law enforcement agencies since the early 1970s. It is a modified version of the M14 rifle, which was the standard issue infantry rifle of the US Army during the Vietnam War. History: The M21 was developed to address the need for a more accurate and versatile sniper rifle than the M14. It was developed by the Rock Island Arsenal in Illinois in collaboration with the US Army Marksmanship Training Unit. The M21 was first introduced into service in 1975, and it quickly proved to be an effective weapon for snipers. The M21 is based on the M14 rifle, which was developed in the late 1950s. The M14 was designed to replace the M1 Garand rifle, which had been the standard issue infantry rifle of the US Army since World War II. The M14 was semi-automatic, which meant that it could fire one round with each pull of the trigger. It was chambered in 7.62x51mm NATO, which was a powerful cart