The M16

Hi, I’m Chris and welcome back to the educational video series! In this episode, we’re diving into the M16.   

Origins: From AR-15 to M16  

The M16 was born from the AR-15. Eugene Stoner, a WWII veteran and the innovative engineer at ArmaLite and his team were charged by the Army to design a lighter, modern alternative to the heavy battle rifles. After several different prototypes, many of which did not get through to production, Stoner and his team came up with the AR-15. It was chambered in a lighter, high-velocity .223 Remington cartridge, had select fire capabilities and was considerably lighter than previous rifles weighing in at just over 7 pounds fully loaded. This was thanks to the use of plastics and aircraft grade aluminum.   

When applied to a military situation, this firearm was revolutionary – soldiers could carry more ammo, fire with less recoil, and still have effective range. After extensive discussions and the sale of the AR-15 plans to the Colt Patent Firearms Manufacturing Company, Colt stepped up promotion of the AR-15 and by the early 60s, it was adopted by the military and designated the M16. 

The Design That Stood Out  

The M16 was made with aluminum receivers, so it weighed far less than its predecessors, including the M14. The rifle’s operating system used a direct impingement gas system, which vented gas straight back into the action. This made for an efficient, lightweight design. Combine that with its slim profile, 20-inch barrel, and 20-round detachable magazine, the M16 ushered in a new era of military rifles. Gone were the days of the wood and steel rifles the M16 replaced.  

When the M16 was first fielded  

The M16s first saw action in Vietnam and initially, the results were overly positive with Lt. Col. Hal Moore calling it the “best individual infantry weapon ever made” after the battle of LZ X-Ray. However, before a full-scale deployment of the M16 was made, changes were implemented based on results of continual field testing in the United States. The rifling was changed from 1:14 or one twist over 14 inches to 1:12. While this change gave the projectile more stability for closer groupings, it may have negatively impacted its lethality.  

In 1966-1967, after these changes were implemented, the M16 showed catastrophic problems in the field. The main problem was jamming. When the rifle jammed, the only way to fix it was to field strip and reassemble it. Under heavy enemy fire, this “fix” often had deadly consequences. There were also many instances of “failure to extract” when the casing would fail to properly eject. Despite some models having a forward assist feature, that was sometimes of limited help. Cleaning kits weren’t provided because it was falsely assumed that the M16 was “self-cleaning”.  In the humidity and grit of the Vietnam jungles, soldiers learned the hard way that the rifle was unforgiving if not properly maintained.   

The results were deadly. Congress held hearings on the matter. For many, it looked like the M16 was a failure. A full review showed that the malfunctions were primarily caused by changes made to the ammunition. After successful initial tests, a different propellent with higher chamber pressures and burn rates was used in production. This small change led to higher rates of fire, increased fouling and subsequent malfunctions. Since there were no lubricants designed for the M-16 at the time, soldiers resorted to using field expedients such as motor oil or other lubricants which increased the likelihood of jamming due to the high fouling caused by the ammunition.  

The M16 was at a critical juncture. Could changes be implemented to revitalize the potential initially seen with the M16 or would the Army go back to the drawing board? Find out next time.