The “Mattel Gun” – History of the Venerable M-16 Rifle

The “Mattel Gun” – History of the Venerable M-16 Rifle

Doug Livermore

The M-16 rifle, first officially adopted into the American military’s inventory in 1964 and chambered for 5.56x45mm NATO ammunition, has served as the basic assault rifle of the United States for well over half a century.[i] Approximately eight million M-16-pattern rifles have been produced, with the rifle’s intermediate caliber helping make it one of the most popular weapons in today’s defense and civilian marketplaces.[ii] When the M-16 was first introduced, it revolutionized firearm design with its use of composite materials, intermediate caliber ammunition, and space-age appearance. Despite some initial reliability issues, evolutions of the design produced a highly- capable firearm. Modern variants of the original M-16 rifle serve as a standard issued firearm across all services of the Department of Defense. Most modern military rifles since the introduction of the M-16 share at least some characteristics with the now-ubiquitous weapon system. With continuing modernization, it is likely that some variant of the M-16 will continue serving U.S. forces and other international customers well into the future.

The world’s first viable assault rifle was the German Sturmgewehr-44 (StG-44), which was introduced toward the end of World War II and provided selective fire of an intermediate cartridge (7.92x33mm Kurz-German for “short”) from a box magazine.[iii] Intermediate cartridges, while less powerful than full-sized rifle ammunition, provided superior performance to the pistol cartridges used by submachine guns then in widespread use among all the WWII belligerents. Shortly after the war, the Soviet Avtomát Kaláshnikova-47 (AK-47) emerged as the spiritual successor to the German StG-44. The AK-47 fired the 7.62x39mm intermediate round and provided the Soviet soldier in the early years of the Cold War the ability to lay down overwhelming fire unlike anything then available to U.S. or its allies.[iv] Small arms designers in Western nations continued to rely on the full-sized rifle cartridge, particularly the 7.62x51mm NATO round, which was nearly uncontrollable when fired in other fully automatic infantry rifles then fielded. The British Army adopted the Fabrique Nationale Fusil Automatique Leger (FN FAL) and the West Germans the Heckler and Koch G3 (HK G3), both which were selective fire battle rifles chambered in the 7.62mm NATO round.[v] The Springfield M-14 rifle, which the U.S. adopted in 1959, was essentially a modernization of the WWII-era M1 Garand rifle updated to fire the same full-sized NATO round from a box magazine with the option of fully-automatic fire.[vi] The disadvantages of the M-14 became evident when U.S. troops encountered North Vietnamese forces using AK-47s in the jungles of Southeast Asia. American forces with their M-14s could not match the sustained automatic fire from Communist troops armed with AK-47s, prompting many in the U.S. military to demand a new, selective fire rifle using an intermediate cartridge.[vii]

The conceptual rifle that would eventually become the M-16 began its journey as the AR-10 developed by the U.S. firearm company Armalite, where its chief designers were the now-famous Eugene Stoner and L. James Sullivan.[viii] Armalite designed and entered the AR-10, which was chambered in 7.62mm NATO, late into the 1956 U.S. Army trials to replace the obsolete M1 Garand. The AR-10 introduced several innovative features, including significant use of phenolic composite materials, forged alloy parts, and a straight-line barrel-to-stock design that made the AR-10 incredibly stable and light.[ix] Also in these trials were the FN FAL and the prototype M-14 rifle, which ultimately won the trials and was adopted into the Army inventory.[x] However, Armalite was also working on a variant of the AR-10, called the AR-15, which was nearly identical to the AR-10 except for being chambered in the popular, and much smaller, .223 caliber (5.56x45mm) civilian ammunition.[xi] The Colt firearm company purchased Armalite in 1959 and began selling AR-15 rifles to several international customers, such as the Malaysian military. Despite the glaring inadequacies demonstrated by the M-14 rifle in Vietnam, the U.S. Army resisted calls from the field and multiple studies recommending replacement of the heavy, uncontrollable rifle. Finally, in 1963, Secretary of Defense Robert McNamara directed the adoption of the AR-15, now re-designated the M-16, when it was revealed that Springfield was unable to produce enough M-14 rifles to fulfill the U.S. military’s needs.[xii] Given the space-age design and light weight of the M-16, many U.S. troops took to calling the new rifle the “Mattel Gun” in reference to the popular toy company. Early M-16s used in Vietnam suffered from several issues which negatively affected its reliability, which will be discussed later. However, Colt made rapid modifications to the M-16, greatly improving the performance of the rifle and addressing other identified issues with the M-16A1. Evolution of the M-16 rifle continued after the Vietnam War and NATO adopted a modified .223 caliber round officially designated 5.56x45mm NATO as a standard ammunition type in 1980.[xiii] Today, the M4 carbine, a shortened variant of the M-16 rifle, is the standard firearm for every U.S. military service except the U.S. Marine Corps, which fields an updated M-16A4 rifle.[xiv]       

The M-16 family of weapon systems provides troops with a lightweight, reliable firearm that allows selective fire of a highly-capable intermediate round. Firing rounds from a detachable box magazine, the action of the M-16 cycles due to a direct gas impingement system by which pressure from the firing round is routed through a hollow tube that runs parallel to the barrel back to the bolt carrier group.[xv] Original M-16 rifles used a rear peep sight adjustable for windage (left and right adjustments) and a front sight post adjustable for elevation (up and down adjustment), though later models have rail systems for mounting a wide range of magnified, holographic, and traditional “iron” sights. By using composite materials throughout the rifle, the M-16 saves precious weight that troops can better use to carry additional ammunition or other critical equipment. In sustained combat, the lighter overall weight of the M-16 and its variants is a marked advantage over heavier rifles which can wear down troops carrying the weapon. Unlike the M-14, which it replaced, the M-16 is also much more controllable while firing on burst or automatic modes, allowing for the delivery of highly accurate, overwhelming fires against targets. Finally, the 5.56x45mm NATO round fired by the M-16 and its variants has a very high muzzle velocity, resulting in a flat trajectory and improved accuracy over longer ranges.[xvi]

Despite its long service history, the M-16 and its variants have suffered from a number of issues. With innovation and effort, most of these issues have been overcome, though some issues are inherent in the basic design of the weapon system. Early models of the M-16 rifle used in Vietnam suffered reliability issues, though many of these issues were caused by inferior ammunition propellant, insufficient cleaning supplies, and inadequate maintenance training for American troops deployed to Vietnam.[xvii] However, these conditions only exacerbated an inherent issue with the M-16’s design, namely its direct gas-impingement system. This system increases fouling of the weapon’s action, a problem that the AK-47 avoids by using a gas piston system.[xviii]  The AK-47’s system uses the pressure from fired rounds to push a solid rod back parallel to the barrel to cycle the action, resulting in less fouling of the action. Some companies, like Heckler and Koch, now make relatively inexpensive M-16-style weapons that use the superior gas piston systems and are particularly popular with special operations forces.[xix] Even after more than 60 years since the design’s genesis, M-16-style rifles are still produced by countless companies and are incredibly popular with both national militaries and civilian shooters around the world.

The views expressed in this article do not represent the positions of the Department of Defense or any other part of the US Government.

End Notes