US Army M21 Sniper Rifle
September 12, 2019
Due to the USMC’s impressive PR campaign I’m sure many readers would just assume the top sniper during our war in Vietnam was a Marine wielding an M40. However, the truth may surprise you. Not only was a relatively unknown US Army Staff Sergeant the highest scoring sniper in Vietnam, but he did it with a semi-automatic M21. Credited with 109 kills Staff Sergeant Adelbert Waldron proved an M14 based sniper rifle could run with the USMC’s Model 70 Winchester target rifles and newer Remington M40 sniper rifles in actual combat. As a member of Company B, 3d Battalion, 60th Infantry Regiment of the 9th Infantry Division he found himself hunting with the ‘Brown Water’ Navy in the Mekong Delta. His feats included nine kills in one night using an AN/PVS-2 Starlight scope and a 900 meter shot from a moving naval vessel.
The sniper rifle he carried was a M14 National Match topped with a 3-9x Adjustable Ranging Telescope (ART). This combination would later be designated the M21. The M21 was developed during Vietnam and remained the standard US Army sniper rifle until replaced by the bolt-action M24 in 1988. The M21 sniper rifle itself though was little more than a M14 built to National Match specifications topped with a scope. An offshoot of a straight competition rifle, the US Army sniper program benefited directly from technology developed by the ‘yellow glasses’. Selected rifles received match grade barrels, unitized gas systems, trimmed handguards, reamed flash suppressors, triggers were adjusted to slightly over 4.5 pounds, National Match sights were fitted and actions glass bedded.
Mounted to the side of the receiver was a unique sniper scope, the ART. Designed by Captain James R. Leatherwood and manufactured by Redfield, this optic allowed a sniper to easily range a man by zooming the magnification in or out until he fit between two marks on the reticle. Simultaneously the magnification ring cammed the scope up or down, automatically adjusting the range. So all the sniper had to do was bracket his target (which automatically adjusted the elevation), adjust for wind/lead and fire. It proved to be a very fast and simple system to use under actual battlefield conditions. In addition the 7.62x51mm 173 grain FMJ-BT M118 National Match load became standard issue for snipers. This competition load offered a dramatic step up in accuracy over standard 147 grain M80 ball.
While a good rifle, the M21 had its weak points. Namely the 3-9x ART scope was insufficiently rugged and the rifle required a well trained honest to God armorer to properly maintain it. It fell out of favor after the lessons of Vietnam had been forgotten, only to be pressed back into service in Afghanistan and Iraq.
US Army M21 Sniper Rifle SpecificationsAction
Type: Short-stroke gas with rotating boltCaliber
: 7.62x51mm NATOCapacity
: 20 round detachable box magazineBarrel
: 22 inches 1-11.25 inch twist Overall Length
: 44 inchesWeight
: 11.5 poundsStock
: Hardwood with glass beddingFinish
: 4.5 pound pull per National Match specificationsIron Sights
: NM post front, hooded NM rearOptical Sight
: 3-9x Adjustable Ranging Telescope and ART IIDedicated Sniper Load
: 173 grain FMJ-BT M118 National Match