M21 Rifle The Legacy of Army Snipers - Inside MDT

Posted by Cory Ross on 2024 Feb 29th

M21 Rifle The Legacy of Army Snipers - Inside MDT

The famed M14 battle rifle is both highly regarded and infamous. It has doubters and believers. However, it was the little rifle that could. It is both one of the shortest-lived service rifles and one of the longest-issued. The rifle is a dichotomy. While its life as a standard-issued rifle to GIs was short-lived—not even reaching a decade—Its persistence and longevity have been its issuance as both a Sniper and Designated Marksman Rifle. In the murky jungles of Vietnam, the M14 secured its place in the pantheon of American Sniper Rifles.

More: The M40 Rifle: a Brief History


Like their Marine counterparts, Army brass soon realized the need for accurate long-range fire to engage distant targets and to conduct counter-sniper missions. Without a dedicated sniper rifle to turn to, Army snipers used aged M1C and D Garands from the Second World War. Some lucky snipers received accurized M14s that had been used from marksman competitions. Conversely, the Army moved slowly in developing sniper doctrine, especially compared to the Marine Corps. To them, sniping was an extra duty tacked onto the tasks of the typical rifleman. This slow matriculation finally gained speed on February 23, 1967, when the Headquarters, U.S. Army, Vietnam, issued a “Letter of Instruction” to the Army Concept Team in Vietnam (ACTIV) to “determine the organizational, doctrinal, and material requirements for sniper operations by U.S. Army units in the Republic of Vietnam.” All ahead full.

M16 on the left, M21 on the right.


Army leadership finally understood the strategic potential and need for snipers. Unlike the Marines, the Army took a more methodical approach to selecting a rifle and training standards. Following the issuance of instruction to ACTIV, an information-gathering campaign ensued. ACTIV worked diligently rounding up information, evidence, and first-hand accounts from field commanders utilizing snipers, even if those commanders had limited sniping resources. This also included communication with the Army Marksmanship Training Unit in Fort Benning, Georgia (USAMTU). While not trained in the art of stalking, these were the Army’s premier marksmen and were experts on rifles and riflery. The USAMTU could advise on rifles, precision shooting techniques, and other needed equipment.

That Spring, Winchester Model 70 rifles, M14s, and telescopic sights for M16s arrived at the Jungle Paradise. For the next six months, ACTIV observed and collected data as they began to formulate a concise outlook on sniper operations in Vietnam. On February 23, 1968—exactly one year later—ACTIV’s findings were issued in the classified document titled “Sniper

Operations and Equipment.” In it, ACTIV recommended:

  1. Divisions and separate command brigades are authorized sniper equipment in addition to TOE weapons.
  2. Organization for sniper operations is tailored by divisions and brigades in accordance with their requirements.
  3. The accurized M14 be designated as the standard sniper rifle in Vietnam.
  4. A standard sniper telescope should be designated.
  5. A sniper training program will be provided for units in Vietnam.
  6. Expand doctrine for employment of snipers to be developed and included in appropriate field manuals.

ACTIV’s listings were further augmented in an official document titled “Equipment for the American Sniper.” In it, Marine Captain George Owen Van Orden and Chief Gunner Calvin Lloyd noted, “It is safe to say that the American sniper could be regarded as the greatest all-around rifleman the world has ever known, and his equipment should include the best aids to his dangerous calling that the inventive genius of the United States can produce.” For American snipers to be successful, they needed the military-industrial might of the United States.

Vietnam-era sniper rifles. Top, M21 Rifle. Bottom, Marine Corps M40.


The Army, which sought to develop sniper tactics, training, and systems in-country (rather than in the U.S.), needed an off-the-shelf option for a rifle. This either needed to be existing military hardware or civilian-built. The first four rifles reviewed included an accurized M14 with a 2.5X M84 riflescope, the M14 National Match Rifle (as used by the USAMTU) outfitted with a 3X-9X adjustable range scope, an M16 with a 3X Realist sight, and finally, the Winchester Model 70 with a 3X Weaver scope. Similar to the Marine Corps, the Model 70 was quickly relegated because of its 30-06 chambering. Moreover, without match-grade ammunition available for the M16, it too faltered, although the premise of an accurized M16 platform would persist until fruition during the Global War on Terror (GWOT).

As for the two M14 variants, not much differentiated them. The only variance was the mounting systems for their respective optics. Selected M14 rifles received match-grade barrels, unitized gas systems, trimmed handguards, and reamed flash suppressors. The rifle’s triggers were adjusted to slightly over 4.5 pounds, National Match sights were fitted, and actions glass bedded. The Army also had access to the famed Lake City M118 7.62x51mm match ammo that the Marines did. Interestingly, the Army did not consider one of Remington’s rifles. They felt the difference in performance between the M14 and the Model 700 was negligible.

End users felt between 75% and 100% confident in the M14 system, with the 3X-9X optic option receiving higher praise. In ACTIV’s final report, examiners stated, “The major reason for the preference of the M14 was greater range and accuracy. The limited number of commanders who had experience with the M14 w/ ART preferred it to the M14 w/ M84 because of the power and the range-finding feature of the telescope.” ACTIVE concluded that the Accurized M14 “be designated as the standard sniper rifle for Vietnam.” (This, of course, was not limited to the Vietnam conflict but to global units). Neither tested optic possessed all the qualifications, and eventually, the Redfield 3X-9X was adopted (the same optic as seen on the Marine’s M40 rifle). In February of 1969, The M14 was adopted as the XM-21, and Rock Island Arsenal quickly went to work. Throughout the war, Rock Island built over 1200 rifles. In 1972, the XM21 was officially adopted as the Rifle, 7.62mm Sniper 21, or simply, the M21.

Vietnam sniper with a suppressed M21 and PVS2 Starlight scope.

The M21 maintained a wide range of praise as well as despise. Its service life extended well beyond the Fall of Saigon. However, the weapon was never meant to be a sniper rifle. The biggest downfall was the nature of the system itself. Its accuracy was adequate for general infantryman use, but to wring the most out of the platform required actual armorers. This meant field service proved problematic; the average soldier couldn’t work on their guns like Marine snipers could work on the M40. That is not to say that the M21 wasn’t successful. Army Staff Sergeant Adelbert Waldron of Company B, 3rd Battalion, 60th Infantry Regiment of the 9th Infantry Division was credited with 109 kills, all with the M21 rifle. His feats are legendary.


The legacy of the M21 is murky. Like previous engagements, after the withdrawal from Vietnam, the Army’s sniper program went dormant. However, in the late 1970s, there was rekindled interest in a dedicated sniper school (a result of global implications during the height of the Cold War). The M21 went up against the M40A1 and other commercially available rifles. The rifle held its own, but in 1988, after a much longer than expected service life, the M21 was replaced by the M24 bolt action rifle (a similar rifle to the Marine’s M40A1).

Interestingly, the M21 rifle won’t go out without a fight. As the 21st-century conflicts in Afghanistan and Iraq grew in scope and mission, the United States Army needed a force multiplier weapon to augment its snipers. The M21 was again thrust into combat by both snipers and newly formed Designated Marksman Units to add complimentary precision fire to small units. One particularly interesting side note on the rifle’s history was the creation and implementation of the M14 EBR (Enhanced Battle Rifle). Designed by Doug Carlstrom of Rock Island Arsenal (and GWOT Veteran), the M14 EBR-RI was designed to standardize optic selection (a Leupold Mark 4 LR/T 3.5-10X40), a chassis constructed from lightweight aircraft aluminum (Sage International) capable of supporting the use of a night vision device that sits in front of the day optic and use a variety of combat-related accessories never seen before this age of warfare. This had to be an out-of-the-box system that could be easily picked up by soldiers. Officials at the Pentagon considered the M14 EBR-RI an interim solution and eventually replaced it with the M110 (and later DMR-style rifles).

GWOT soldiers getting it done with the M14 EBR.

The M21 is an important rifle to study when understanding the history of American Snipers. Like the Marine’s M40, the M21 was developed at the height of sniper development. While previous conflicts utilized snipers in various capacities, it was in the Jungles of Vietnam that military strategists began to understand their importance on the battlefield. The M14, a marginalized battle rifle, proved to be one of history’s most important as it aided in transforming American Snipers.

A special thanks to all who served in South East Asia.

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I have worked in the firearms industry for 11 years and counting. What started as a part-time job during undergrad has become a career. In that time, I have been lucky to work with some incredible people and companies. I also completed a Master of Arts in History from Cleveland State University. When I am not shooting, reloading, or working on my firearms, I am reading, writing, and tinkering with Legos.


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