US Army M21 Sniper Rifle

US Army M21 Sniper Rifle
The M21 sniper rifle was developed during Vietnam and remained the standard issue US Army sniper rifle until 1988. It was based upon the M14 National Match.

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.

US Army M21 Sniper Rifle
Mounted to the side of the M21 was a unique 3-9x40mm ART scope.

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.

US Army M21 Sniper Rifle
Sergeant Adelbert Waldron was the top scoring US sniper in Vietnam with 109 kills. He is seen here with his XM-21 sniper rifle.

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. 

US Army M21 Sniper Rifle
A 25th Infantry Division sniper is seen here in Vietnam wielding an XM21 sniper rifle outfitted with an AN/PVS-2 Starlight scope and Sionics sound suppressor. This was state of the art at the time.

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 Specifications

Action Type: Short-stroke gas with rotating bolt
Caliber: 7.62x51mm NATO
Capacity: 20 round detachable box magazine
Barrel: 22 inches 1-11.25 inch twist
Overall Length: 44 inches
Weight: 11.5 pounds
Stock: Hardwood with glass bedding
Finish: phosphate
Trigger: 4.5 pound pull per National Match specifications
Iron Sights: NM post front, hooded NM rear
Optical Sight: 3-9x Adjustable Ranging Telescope and ART II
Dedicated Sniper Load: 173 grain FMJ-BT M118 National Match

GET THE NEWSLETTER Join the List and Never Miss a Thing.

Recommended Articles

See More Recommendations

Popular Videos

New handguns from Smith & Wesson

New handguns from Smith & Wesson

The Performance Center's M&P380 Shield EZ pistol features ported barrel, flat face trigger and tuned action.

Performance Center M&P Shield M2.0

Performance Center M&P Shield M2.0

From Smith & Wesson, the M&P Shield M2.0 is a great option for a carry gun with optics option.

New addition to the Browning X-Bolt rifle series

New addition to the Browning X-Bolt rifle series

New for 2019 is the Max Long Range model featuring a composite Max stock with fully adjustable comb, spacers for adjusting length of pull, stainless fluted heavy sporter barrel, threaded muzzle brake and extended bolt handle.

Ruger introduces Rifles Chambered in the All-New .350 Legend

Ruger introduces Rifles Chambered in the All-New .350 Legend

Two Ruger American Ranch rifles and the AR-556 MPR are now chambered for Winchester's .350 Legend cartridge.

See More Popular Videos

Trending Articles

A $50 Ring Loc-Kit gives AirForce Condor airgunners unparalleled power and accuracy. Air Guns

AirForce Airguns Condor Ring-Loc Kit Review

Tom Gaylord - May 29, 2019

A $50 Ring Loc-Kit gives AirForce Condor airgunners unparalleled power and accuracy.

Please sign and share the petition to get the required 100,000 signatures by July 27. 2nd Amendment

Tell the White House that the 2nd Amendment Was Not Given to the People by Government

Firearms News - July 02, 2019

Please sign and share the petition to get the required 100,000 signatures by July 27.

This will be the first of many investigative reports about the NRA by Firearms News. 2nd Amendment

Firearms News Investigates the NRA: Part 1

Nedd Scott - July 18, 2019

This will be the first of many investigative reports about the NRA by Firearms News.

No one can restore receptivity to another Trump term with these disaffected gun owners but the president himself. 2nd Amendment

2020 is Trump's to Blow with Gun Owners

David Codrea - July 09, 2019

No one can restore receptivity to another Trump term with these disaffected gun owners but the...

See More Trending Articles

More Rifles

The Soviet short sword of World War II was the Pistolet Pulyemet Shpagin-1941 (PPSh-41) submachine gun. Rifles

Shooting the Soviet 7.62x25mm PPSh-41 Submachine Gun

David M. Fortier - July 11, 2019

The Soviet short sword of World War II was the Pistolet Pulyemet Shpagin-1941 (PPSh-41)...

The ATI GSG-16 can fulfill your MP5 fantasies with the enjoyment of low-cost .22 LR! Rifles

ATI GSG-16 Review

Vincent L. DeNiro, Editor - October 30, 2019

The ATI GSG-16 can fulfill your MP5 fantasies with the enjoyment of low-cost .22 LR!

The Russian Vityaz 9mm submachine gun is based on the Bizon series, it fires from the closed-bolt position and is a simple blow-back design which feeds from 30-round magazines. Rifles

Russia's AK 9mm Vityaz Submachine Gun

David M. Fortier - September 13, 2019

The Russian Vityaz 9mm submachine gun is based on the Bizon series, it fires from the...

The SIG PE57 is a true classic battle rifle, and one of the most desired MSRs by collectors today. Rifles

SIG PE57 Battle Rifle

Leroy Thompson - August 07, 2019

The SIG PE57 is a true classic battle rifle, and one of the most desired MSRs by collectors...

See More Rifles

GET THE MAGAZINE Subscribe & Save

Temporary Price Reduction.

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW OUR CURRENT ISSUE

GET THE NEWSLETTER Join the List and Never Miss a Thing.