M16: The U.S. Army Rifle That Creates So Much Controversy

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Key Points: The M16 rifle’s adoption marked a turning point in U.S. military rifle design, moving away from traditional .30 caliber rounds to a lighter, high-velocity 5.56mm caliber.

-Born from Eugene Stoner’s AR-15, the M16 faced resistance from an Army committed to larger calibers.

-Testing proved its merits, showcasing improved accuracy, wounding capacity, and portability. Initial Vietnam deployment was marred by reliability issues, but improvements solidified its reputation.

-The M16’s controversial adoption reshaped infantry tactics and remains a competitive platform. Its legacy underscores the importance of innovation in military small arms, challenging traditional norms to meet evolving battlefield needs.

The M16’s Controversial Origins: How It Revolutionized U.S. Military Rifles

The M16 is one of the more controversial firearms to ever be adopted by the United States military. 

Not only did it have a disastrous introduction in Vietnam, but it strayed away from the .30 caliber projectile, a sin tantamount to heresy by the standards of the Army. Further, it was made of aluminum, steel, and polymer, not wood and steel.

The idea behind the gun dates back more than a decade before its adoption, and repeatedly the M16 had to prove itself. 

An effectiveness study of the infantry rifle

According to The Black Rifle: M16 Retrospective book, Colonel Studler ordered the first study of rifle effectiveness in 1950, and Donald Hall of Aberdeen’s Ballistics Research Laboratories was tasked with conducting the study.

In 1952, Hall published An Effectiveness Study of the Infantry Rifle presenting the results. 

The study was unorthodox for the time and seemed to stray away from the Army’s requirement for range and penetration and, most importantly, the .30 caliber rifle round – this was tantamount to blasphemy at the time. 

Instead, Hall’s study focused on three factors of an effective rifle: the soldier’s ability to hit a target; the bullet’s ability to wound; and the weight of the rifle and ammo. This led to the conclusion that if we fixed the weight for weapons and ammo at 15 pounds, a soldier carrying a .21 caliber rifle would be capable of killing 2.5 times as many targets as with the .30 M1 rifle. 

Part of the study included producing a .22 caliber rifle for testing. Aberdeen put together a .22 caliber M2 Carbine that used a proprietary projectile and case design. This rifle proved the concept worked and could work almost as well as the .30 caliber M1 with some changes to the projectile design. 

The Hitchman Report 

In 1957, General Willard Wyman, commanding general of Continental Army Command, saw the Armalite AR-10 at a demonstration at Fort Monroe. He was impressed and spoke with Eugene Stoner. They discussed a .22 caliber rifle with respectable accuracy at 300 yards. 

Wyman made a recommendation to the Infantry Board which then submitted a formal request for the weapon. The board wanted a 5.56 caliber rifle that was select fire and weighed six pounds. The requirement was for the rifle round to penetrate a U.S. helmet at 500 yards. 

US Marine Corps (USMC) members from L Company, 3rd Battalion, 3rd Marine Regiment, 3rd Marine Division, perform a biathlon on the Camp Hansen ranges, firing a Colt 5.56mm M16A2 Assault Rifle.

This led to the scaled-down AR-10, which became the AR-15 in 1957. In 1958, the Army’s Combat Developments Experimentation Command experimented with the AR-15. The experiment paired the M14, the AR-15, and the Winchester’s Light Weight Military Rifle against each other. The command armed squads of troops with each rifle, and tested their performance. 

In the end, the recommendation was that the Army adopt the AR-15. This gained the attention of U.S. Air Force General Curtis LeMay, who was impressed with the rifle. As they say, history was made, and the Air Force adopted the AR-15 as its standard rifle. This officially kicked off the adoption of the M16 – which is adapted from the AR-15 – in 1964. 

SAWS comes as the epilogue

In 1965, after the official adoption of the M16, the SAWS, or Small Arms Weapons System test took place, in which the Army tested squads armed with a wide variety of weapons. This radical test aimed to find the right combination of weapons for the infantry squad. It tested squads solely armed with the M16; mixed squads with various belt-fed machine guns, like the AR-18 and the G3 in 5.56; and squads armed with Soviet guns for comparison.

M16A4 Variant of M16 Rifle. Image Credit: Creative Commons.

Troops were put through various ranges and marksmanship tests. The test concluded that the AR-15/M16 was indeed the best option and that a 5.56 machine gun had great potential. 

The M16 had a very long road to adoption pockmarked by Big Army’s attempt to keep the idea of a small caliber, high-velocity weapon from ever being adopted, as it was set on the .30 cal round and the great big infantry rifle. However, after exhaustive testing, studies, and combat, the M16 proved to be the best rifle for the job and to this day still performs well against more modern competition. 

About the Author: Travis Pike 

Travis Pike is a former Marine Machine gunner who served with 2nd Bn 2nd Marines for 5 years. He deployed in 2009 to Afghanistan and again in 2011 with the 22nd MEU(SOC) during a record-setting 11 months at sea. He’s trained with the Romanian Army, the Spanish Marines, the Emirate Marines, and the Afghan National Army. He serves as an NRA certified pistol instructor and teaches concealed carry classes.