M21 Sniper Weapon System

Rifle, 7.62 mm, Sniper, M21
M21 sniper rifle
Type	Semi-automatic sniper rifle
Place of origin	United States
Service history
In service	1969–present
Used by	See Users
Wars	Vietnam War, Iraq War (Limited use)
Production history
Designer	Marines Weapons Command, Combat Development Command, Limited Warfare Agency
Designed	1969
Manufacturer	Rock Island Arsenal, Springfield Armory
Variants	M25
Specifications
Weight	5.27 kg (11.6 lb)
Length	1118 mm (44 in)
Barrel length	560 mm (22 in)
Cartridge	7.62×51mm NATO
Action	Gas-operated, rotating bolt
Muzzle velocity	853 m/s (2,800 ft/s)
Effective firing range	822 m (900 yd)
Feed system	5-, 10-, or 20-round detachable box magazine
Sights	Front: National Match front blade .062 Rear: Match-grade hooded aperture with one-half minute adjustments for both windage and elevation. 26¾ in sight radius.

The M21 Sniper Weapon System (SWS) is the semi-automatic sniper rifle adaptation of the M14 rifle. It is chambered for the 7.62×51mm NATO cartridge.

The United States Army wanted an accurate sniper rifle during the Vietnam War. The M14 was selected because of its accuracy, reliability, and the ability for a quick follow up shot. As a result, in 1969, the Rock Island Arsenal converted 1,435 National Match (target grade) M14s by adding a Redfield ART Adjustable Ranging Telescope 3–9× and providing National Match grade ammunition (7.62 Lake City Long Range XM-118).

This version, called the XM21, had a specially selected walnut stock and was first fielded in the second half of 1969. An improved version with a fiberglass stock was designated the M21 in 1975. The M21 remained the Army's primary sniper rifle until 1988, when it was replaced by the M24 Sniper Weapon System; some M21s were later re-issued and used in the Iraq War.

In standard military use, the M21 uses a 20-round box magazine as the other members of the M14 family and weighs 11 pounds (5.27 kg) without the scope. The U.S. military never officially authorized or purchased magazines in any other capacity, although 5- and 10-round magazines are available.

The XM21 Sniper Weapon System was used by the U.S. Army in the Vietnam War, and the M21 saw limited action in military conflicts and operations in the late 1960s until the late 1980s. It was used by the U.S. Army Rangers during the Invasion of Grenada in 1983. There are limited numbers in some Army National Guard units and in a few specialized active units such as the OPFOR units of the Joint Readiness Training Center. The XM21 served from 1969 to 1975, and the M21 officially served as the main Army sniper rifle from 1975 to 1988 until the introduction of the M24, which had supplanted the M21 in Ranger Battalions by 1990. Though many M14 and M21 variants came back into favor in the Iraq and Afghan wars in the 2000s.

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