M21 Sniper Weapon System
Springfield Armory (US Government) · Sniper Rifle · Out Of Production · 1969
Also known as: M21 SWS, XM21, M14 Sniper
Overview
The M21 Sniper Weapon System was the United States Army's primary sniper rifle from 1969 until its replacement by the M24 SWS in 1988. Based on the M14 battle rifle, the M21 was a semi-automatic sniper weapon built from hand-selected M14 receivers and National Match-grade components, paired with the Adjustable Ranging Telescope (ART) scope. The semi-automatic action gave snipers a decisive advantage in rapid follow-up shots compared to bolt-action rifles, a capability particularly valued in the dense jungle terrain of Vietnam.
Specifications
| Weight (empty) | 5270 g (185.9 oz) |
| Weight (loaded) | 5600 g (197.5 oz) |
| Overall Length | 1120 mm (44.09") |
| Barrel Length | 559 mm (22.01") |
| Action Type | Gas Operated Short Stroke |
| Firing Mechanism | Rotating Bolt |
| Trigger Type | Two Stage |
| Trigger Pull | 22 N (4.9 lbf) |
| Magazine Capacity | 20 rounds |
| Magazine Type | Detachable Box |
| Muzzle Velocity | 853 m/s (2799 fps) |
| Muzzle Energy | 3457 J (2550 ft·lbf) |
| Effective Range | 690 m (755 yd) |
| Maximum Range | 3725 m (4074 yd) |
| Rate of Fire | 40 rpm |
| Barrel Rifling | Right Hand |
| Rifling Twist | 305 mm (12.01") |
| Number of Grooves | 4 |
| Frame Material | Steel |
| Barrel Material | Steel |
| Stock Material | Fiberglass |
| Finish | Parkerized |
Calibers
- 7.62x51mm NATO · primary · 7.62x51mm NATO — also known as .308 Winchester, 7.62mm NATO, 7.62x51mm
Features
- Firing modes: Semi Automatic
- Feed systems: Detachable Box Magazine
- Safety mechanisms: Manual Safety
- Features: Adjustable Ranging Telescope Art, National Match Barrel, National Match Trigger, Glass Bedded Action, Flash Hider, Bipod Compatible, Iron Sights Retained
Variants
- M14 National Match — Competition
- M14 EBR — Enhanced Battle Rifle
Service history
Operators
- United States Army · adopted 1969 · as M21
- Philippine Armed Forces
- South Korean Armed Forces
- Thai Armed Forces
Conflicts
- Vietnam War (1969-1975)
- Invasion of Grenada (1983)
- Invasion of Panama (1989)
- Gulf War (1990-1991)
Production
Estimated total produced: 1,800 · Production years: 1969-1988
Estimated 1,800 M21 rifles assembled from hand-selected M14 components at the US Army Marksmanship Unit, Rock Island Arsenal, and Springfield Armory.
Origin
Country of origin: United States
Discontinued: 1988
Notes
The M21 was developed at the US Army Marksmanship Unit at Fort Benning through the XM21 program beginning in 1966. Each M21 was built from hand-selected M14 components, with the action glass-bedded into a fiberglass stock for improved accuracy. The Adjustable Ranging Telescope (ART) 3-9x scope featured a unique ranging system that automatically adjusted bullet drop compensation as the scope was zoomed. The M21 was required to shoot sub-1.2 MOA groups with match ammunition. The system was officially replaced by the bolt-action M24 in 1988, though M21s continued to see service into the early 2000s in some units.
Background
Gunnery Sergeant Carlos Hathcock, the most legendary American sniper of the Vietnam War with 93 confirmed kills, primarily used a Winchester Model 70 but the M21/XM21 system was developed partly in response to the need for a semi-automatic sniper capability in Vietnam's dense jungle. Army sniper Adelbert Waldron, who achieved the highest number of confirmed kills (109) of any American sniper in Vietnam, used the XM21 extensively in the Mekong Delta, where its semi-automatic capability allowed rapid engagement of fleeting targets from patrol boats.