How the Army’s M16 Keeps Evolving – What is its Future?

It will be one of the longest-serving weapons in Army history. And this is why.

byKyle Mizokami

In the early 1980s, the U.S. Army and Marine Corps decided the M16A1 assault rifle needed an upgrade. The result was an improved version, the M16A2, and later the M16A3, M16A4, and the shorter, compact M4A1 carbine. The story of the M16 post-Vietnam is the story of how a mature, successful weapon design can be adapted to suit a variety of needs and missions.

The U.S. Military adopted the M16 assault rifle in the early 1960s, abandoning the large, high power-battle rifle concept for a lighter, more compact weapon that fired smaller caliber cartridges. The M16 rifle initially drew glowing reviews from U.S. advisers in Vietnam but a number of ugly problems reared their heads as the weapon was issued to ground troops deployed to the Southeast Asia. Although the problems were eventually solved, the M16 gained a reputation for being unreliable, a reputation that dogs it to this day.

(This is part three of a three part series on the M16 Rifle. See partoneandtwo.)

By 1970 a new version of the M16, the M16A1 had solved the most serious issues with the M16 rifle. The lack of corrosion-resistant chrome plating, thin plastic buttstocks, the ease with which the weapon rusted and the substitution of the original gunpowder for a poor substitute caused up to thirty percent of weapons in front-line combat units to be considered unserviceable. The M16A1 corrected most of these problems and was reissued to troops in the field.

Manufacturer Colt and the U.S. Army continued to build on the M16A1, making it a more dangerous weapon. In 1969, the Army began issuing thirty-round magazines for the M16. As early as 1963 the Army was interested in equipping the M16 with a forty-millimeter grenade launcher, and in December 1966 the first XM148 underbarrel grenade launchers were shipped to Vietnam. A breech loaded, single shot grenade launcher, the XM148’s trial by fire was short lived as five months later the Army reported it was “unsatisfactory for use in the Vietnam environment.” By 1969 the Army had selected a new grenade launcher, the M203, which served into the 2010s. The M203 is currently being replaced by the Heckler and Koch-designed M320.

The M16A1 itself served into the early 1980s, participating in the invasion of Panama, the Beirut peacekeeping mission, and arming mechanized infantry units facing down the Warsaw Pact and Red Army in Western Europe.