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 second shot. As a result, in 1969, the Rock Island Arsenal converted 1,435 National Match (target grade) M14s by adding a Leatherwood 3–9× Adjustable Ranging Telescope and providing National Match grade ammunition. It 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 M21A5 version is built by Smith Enterprise Inc. and is known commercially as the Crazy Horse rifle. The M21A5's metal components are cryogenically treated prior to assembly, which eliminates the need for bedding the stock with fiberglass. Additional upgrades include a completely adjustable trigger system (from 2.5 to 5 lbs) and an extended bolt handle for use in extreme cold environments.
M25 Sniper Weapon SystemEdit
The M25 is an upgraded version of the M21 developed by 10th Special Forces Group's armorers for use by United States Army Special Forces and United States Navy SEALs in the late 1980s. It saw some use during Operation Desert Storm in January and February 1991.
- Action: A M14NM (National Match) action.
- Stock: A McMillan M1A fiberglass stock
- Optics: A Bausch & Lomb Tactical 10×40 scope, or sometimes Leupold MK4 10× scopes.
- Bipod: A Harris bipod is often attached for stability during prone firing.
The XM21 Sniper Weapon System was used by the U.S. Army in the Vietnam War, and saw limited action in military conflicts and operations in the late 1960s until the late 1980s. 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.
Springfield Armory, Inc. also manufactures variants of its M1A rifle called M21 Tactical Rifle and M25 White Feather Tactical/Carlos Hathcock rifle, which are based upon M21 and M25 Sniper Weapon Systems but are slightly different, most notably they are fitted with a Picatinny rail to mount a scope.