The M16 Through M4: A History

By JIM PURCELL

After World War II, into the 1950s, the United States armed forces was on a search to replace a slew of rifles and weapons being used throughout the uniform services. The weapons considered outdated by the military at that time included: the M1 Garand, M1/M2 carbines, the M3 “Grease Gun” and the Thompson submachine gun.

The M16A1 Rifle with 30-Round Magazine

   The M1 carbine came close to being that weapon, but during the Korean War (1950-1953), the ‘powers that be’ in the various services decided the .30 carbine round was under-powered for what they wanted.

   The idea that drove the creation of the M16 was the need to incorporate some functionality from all the weapons noted, but an “intermediate” round was what was wanted. Prior to the M1 Carbine, the main battle rifle for U.S. forces had been the tried-and-true, semiautomatic M1 Garand. It can be argued it was the weapon that won World War II. It was a relatively heavy weapon, at about 10 pounds, it fired a large round (7.62 x 63mm) and the military wanted a round that was somewhere between the small .30 carb and large-bore 7.62.

The M1 Garand, the rifle that won World War II

            The M16 vs. M14

   Many military veterans would immediately bring up the M-14 rifle, which was also a 7.62mm weapon that was standard issue throughout the military beginning in 1959 and concluding in 1964. Well, the M-16 was the competition for this rifle and the battle of the better rifle was played out on the shores of Southeast Asia, during the Vietnam War (1955-1975).

   Perhaps the most important thing the M16 brought to the table for the military was its round: 5.56x45mm. The upside of this round was not only its punch but its size. It was smaller than the larger, .30 caliber round and more rounds could be carried by soldiers. And, it was a select-fire weapon. That meant the M16 had automatic and semi-automatic settings.

   Essentially, the makers of the M14 and M16 were both working on their prototypes throughout the late 1940s and into the 1950s. But, it was Springfield Armory and its M14, and not Colt and its M16, that came across the finish line first. Still, the benefits of the M16 were compelling to decision-makers throughout the armed forces. And, by 1964, it became standard issue for all the uniformed military services.

The M14 Rifle

   One of the original arguments in favor of the M16 was that it could bring more firepower immediately with its full-automatic feature than the M14 could. Of course, the M14’s larger round had substantially more effective range than the M16’s 5.56 round.

   When I was a young infantryman, going through Infantry School at Ft. Benning, Georgia, in 1983, I had a drill sergeant who said the full-automatic feature to the M16 amounted to “spray and pray mode” and was the abandonment of marksmanship. But, one’s favorite weapon will change with the person, like their politics or sports.

The M16: In The Beginning...

   The original M16A1 was produced with only a 20-round magazine. Of course, by 1969, Colt was producing 30-round magazines for the weapon.

The M16A2 Rifle

   The M16 has its roots in the Armalite AR15. The chairman of the Joint Chiefs of Staff, USAF Gen. Curtis LeMay, saw a demonstration of the AR15 in 1960 and was impressed. Initially, 10 AR15s were sent to Vietnam for use by U.S. soldiers. The reports of the field performance of the weapon were stellar, so 1,000 more AR15s were sent to Vietnam, and they received high marks from soldiers and Marines. The M14 had its proponents, though, and it was only the successor of LeMay, Gen. Maxwell Taylor, who effectively made the argument that there could not be two main battle rifles for the services and that one had to win out over the other to then-president John F. Kennedy. Thus, the story of the M16 and its service to the military began.

The M4 Rifle

   The M14 fired a high velocity round, which often created ‘in and out’ wounds in enemy soldiers. However, bullet fragmentation in the enemy was higher with the M16. This meant that wounds received by enemy soldiers were allegedly more extensive compared to similar wounds made by the M14.

   Any time a weapon is fielded by the military, it goes through product improvements to sort out problems. The M16 had its fair share of problems too. At a rate of two per 1,000 rounds, the M16 was likely to jam initially, earning it the nickname by some as “Jamming Jenny.” But, Colt improved the internal piston system within the M16A1 and the problem was alleviated.

   The M16 was air-cooled, gas operated and magazine fed, with a rotating bolt. The receivers for the weapon are made of 7075 aluminum alloy and its bolt is made of steel. It is a lightweight weapon, at just under 8 pounds and it had a maximum effective range of 460 meters, which made it ideal for jungle fighting.

Gen. Maxwell Taylor was an M16 proponent

       The M16: Rifle Of An Era

   The M16A2 was adopted as the main weapon for the U.S. Marine Corps in 1983, and the U.S. Army in 1986. The M16A2 fires an improved round 5.56x45mm NATO (M855/SS109), and includes improvements to the rear sight aperture and case deflector. The barrel was made heavier and the stock and pistol grips were improved.

   Over time, more improvements were made to the M16 and, in 1998, the M16A4 was fielded by the armed forces, continuing the legacy of service that the M16 rendered to U.S. servicemen and women since the 1960s. Reportedly, 8 million M16s are made annually by Colt, which makes it one of the most-produced weapons in the world.

   One of the most startling changes with the M16 came prior to 2015, when the U.S. Army adopted the M4, which is a shorter, lighter version of the M16. The U.S. Marine Corps went on to adopt the M4 in 2015, and the weapon continues to serve the armed forces as its main battle rifle.  

   Though the M4 is a weapon crafted for conflicts today, it has its roots in the post-World War II race to come up with the best weapon for the latter 20^th century American fighting man and woman. Features of the M16 have been improved and changed over time, but it remains America’s ‘go to’ weapon for land forces.