This is why the iconic M16 rifle has served for so long

Eugene Stoner and the folks at Armalite designed the AR-15 all the way back in 1956. It would be another six years before the U.S. Air Force would adopt the firearm, and a few years later, its M16 iteration would go on to become the weapon of choice for the entire United States military.

However, its adoption wasn’t without controversy.

The Army Material Command initially rejected the weapon for the M14. Yet, an investigation launched by Secretary of the Army Cyrus Vance found that the test was rigged from the start as the Army Material Command used match-grade M14s against out-of-the-box M16s disadvantaging the M16.

Eugene Stoner and his first rifles. (Creative Commons)

Later, when the M16 hit Vietnam, troops were wrongly told the weapon didn’t need to be cleaned so cleaning kits weren’t issued. Additionally, the Army used the wrong propellant in the 5.56 ammo, which created reliability issues.

All these incidents gave the M16 a terrible reputation that continues to plague it, mostly propelled by the uninformed.

However, the success of Stoner’s design has been undeniable and today we will investigate the weapon’s longevity and success.

The simple answer

There’s a very simple answer to explain the M16’s dominance: There isn’t anything better. Sure, some rifles offer some slight improvements over the M16, but these aren’t substantial enough to justify completely changing rifles for an entire military force.

For example, rifles like the SCAR Mk 16 were super hot for a short period but never overtook the M4 (which is a shortened version of the M16). In testing, the SCAR proved to be slightly more reliable than the M4, with fewer stoppages in 6,000 rounds, but only fractionally so. Yet, even when special operations communities had the option to choose between the SCAR and the M4, they still chose the M4.

A soldier in Vietnam firing the M16. (Creative Commons)

Over the years, the Army tried to replace the M16 and M4 series with the Advanced Combat Rifle program, the Objective Individual Combat Weapon program, and the XM8 program. They even tried to replace the M16 in the middle of the Vietnam War when they tested the Stoner 63.

However, try as they might, the M16 always stuck around.

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It’s just a good rifle

During the Cold War, the world moved away from the heavy battle rifle calibers that were used in World War II to the assault rifle concept. The Soviets transitioned first with the AK series, and sometime later, the Americans saw the light too, and eventually Western forces were standardized on 5.56 caliber rifles.

Petty Officer 3rd Class Mathew Roy (left) and Petty Officer 3rd Class Anthony Foster of Naval Mobile Construction Battalion (NMCB) 4 practice their sharp shooting skills with the M16 rifle in Al Anbar province, Iraq, 2007. (Photo by Petty Officer 1st Class Ronald Gutridge/U.S. Navy)

The simple fact of the matter is there are only a few ways to send a 5.56 round downrange, and the M16 is pretty good at doing just that. In terms of small arms, we’ve been at a plateau for quite some time. Major innovations aren’t rolling in, and the world seems to have settled on the intermediate-caliber assault rifle as the main military firearm.

As far as intermediate-caliber assault rifles go, the M16/M4 is an excellent rifle. The design is small and rather lightweight. It’s cheap to produce and surprisingly accurate for a military rifle. Further, the rifle’s direct impingement operating system is very reliable. Lastly, the 5.56 cartridge is quite lethal but is also lightweight, which allows troops to carry more ammo.

Related: These are the 5 best service rifles the US military has ever had

Modularity is always a good thing

U.S. Marine Corps Pfc. Mitchell Funk demonstrates how to look through a rifle combat optic scope attached to an M16A4 rifle on Camp Hansen, Okinawa, Japan, Oct. 18, 2019. (U.S. Marine Corps photo by Sgt. Ryan M. Harvey)

The M16s fielded during Vietnam look a lot different than the URGI rifle or the Mk 18 of the Global War on Terror. Stoner’s M16 was designed to be easily mass-produced, and by happy accident, it also turned out to be easy to adapt. Over the years, the M16 turned into the carbine-length M4 and the even shorter rifles used by special operations forces.

The M16 itself went through several generations, with steady improvements made to the point where the weapon could easily accept optics, lights, lasers, and more. Rifles like the Mk 12, designated marksman’s rifle, were built from the Stoner design which had become well known for its modularity and ability to evolve and adapt as needed.

The end of the M16

The Stoner design has been the military’s service rifle in one form or another from 1962 up until today.

Yet, the rifle’s end has been signaled with combat arms forces replacing the M16 family of rifles: The Marine Corps adopted the M27 IAR for its combat arms forces, and the Army finished the Next Generation Squad Weapon contest and settled on the SIG Spear in a new, hot caliber.

Nevertheless, although the M16 and its legacy designs are slowly being replaced, they will continue to serve for at least several more years.

The M16 has had a very successful life as a service rifle, and even its replacements are largely influenced by it and its AR-15 progenitor. It’s one of the most influential rifles ever made and has certainly served its country of origin well.

Editor’s Note: This article was originally published in March 2024. It has been edited for republication.

Feature Image: U.S. Marines seize apartments at the edge of Fallujah, Iraq, in the first hours of Operation al Fajr (New Dawn) on Nov. 8, 2004. The Marines were assigned to K Company, 3rd Battalion, 5th Marine Regiment, 1st Marine Division that was engaged in security and stabilization operations in the Al Anbar Province of Iraq. (Photo by Lance Cpl. James J. Vooris/U.S. Marine Corps/ Released)

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