The 5.56mm M-16 rifle was developed because of general dissatisfaction with the M-14 rifle. Numerous studies led the Army to the development of a lightweight weapon capable of firing a burst of small caliber bullets with a controlled dispersion pattern. Although opposed by the Ordnance Corp, in 1965 the Armalite AR-15 was adopted by the Secretary of Defense for use by all branches of the U.S. military as the 5.56mm M-16 rifle.
Lt. James Allison of the 4th Infantry Division Rear Area Operation Center (RAOC) fires his M-16A2 rifle at the 4ID firing range in Taji, Iraq, August 2003.
The history of the M-16 rifle begins with Eugene Stoner, the now-legendary designer of military rifles. In 1955, Stoner worked for the ArmaLite division of Fairchild Engine & Airplane Corporation where he designed the AR-10, a selective-fire infantry rifle in 7.62mm NATO caliber. Stoner's AR-10 was an advanced design: smaller, lighter, and easier to handle on automatic than the rifles of the time. US Army rifle trials were in progress at Aberdeen Proving Ground where the AR-10 was entered late in the competition near the end of 1956. At the close of the trials, the Army selected the Springfield Armory T44, standardized as the M-14 rifle. However, the AR-10 was recognized as promissing, if early in its evolution. In 1958, ArmaLite produced a version of the AR-10 chambered for the .223 cal. (5.56 mm) cartridge, for entry into the US Army's lightweight rifle procurement trials. Stoner's engineering team - Robert Fremont and Jim Sullivan -- created the AR-15 from the AR-10, scaling it down to fire the smaller caliber cartridge. ArmaLite then licensed manufacturing and marketing rights to the AR-15 to Colt, in December 1959.
In 1962, early in the Vietnam War, Colt brought the ArmaLite AR-15 to the Advanced Research Projects Agency (ARPA, now DARPA). Impressed, ARPA sponsored a combat demonstration of the AR-15 in Vietnam. The AR-15 was chambered for the .223 cal. (5.56 mm) cartridge, far smaller than the then standard 7.62mm NATO round or the classic .30-06 but promoted as just as lethal due to its high velocity and tumbling on impact.
In October 1961, ARPA provided ten Colt AR-15s to Vietnamese Forces in Saigon to conduct a limited test. The Black Rifle remarks of this test, "The number of rifles might have been small, but the enthusiastic reaction of the Vietnamese and their American advisors alike who handled and fired the AR-15s was just as [Colt's marketing agent] had predicted." Armed with these positive results, ARPA succeeded in expanding the Project AGILE study by procuring 1,000 AR-15s for distribution among select Vietnamese units for field testing. Ezell and Stevens wrote that this approval resulted in "... saving Colt's from almost sure financial disaster and also setting the stage for the most influential yet controversial document so far in the history of the already controversial AR-15."
The AGILE report enthusiasticly supported the AR-15 as "...superior in virtually all respects to the M-1 Rifle, M-1 and M-2 Carbines, Thompson Sub-Machine Gun, and Browning Automatic Rifle." However, this statement was specifically related to equipping the Vietnamese who were small in stature compared to typical US soldiers. Further testing failed to reproduce the lethality claimed by the original report for the 5.56 ammunition.
Even though the AR-15 report and tests of the .223 ammunition were controversial, in 1963 the US Army began purchasing the M16 for use in Vietnam where it was issued to Sepcial Forces. The Army ordered 85,000 rifles in 1963, 35,000 more in 1964, 100,000 in 1965, and 100,000 in 1966. At first they were issued to Special Forces, Airborne, helicopter crews, Air Commando and other special category troops in Vietnam as well as forces in the Dominican Republic.
The M-16 became the military's basic service rifle and was in widespread use by 1966. Troops generally liked the lightweight rifle and the ability to carry more ammo, but complained about insufficient range and lethality. Despite Colt's claims that it was maintenance free, there were early problems due to poor maintenance training, and to the jungle climate of Southeast Asia. It has also been claimed that a change in the 5.56 ammo propellant caused fouling until chrome plating was introduced to offset the problem.
In January 1968, the U.S. Army designated the 5.56mm M16 as the Standard rifle, and the M14 became a Limited Standard weapon.
Through 2003, the total quantity produced in all models world-wide was about 7 million.
M-16 Rifle Characteristics
Rifle, 5.56mm, M-16A2.
The M-16 is selectable for full and automatic fire. The M16 was to have had the same effective range as the M-14 rifle it replaced, but it was most effective at a range of 215 yards (200m) or less. The M-16 used a 5.56mm (.223 cal.) cartridge in 20- or 30-round magazines.
The M-16A2 was introduced in 1982 with improvements over the M-16 and M-16A1. The M-16A2 is equipped with a burst control device so that each pull of the trigger fires one shot if single shots are selected. In automatic fire, the M-16A2 automatically fires a three-shot burst for each trigger-pull, considered optimum from Army research. The M-16A2 also incorporates a more durable plastic handguard, rifle stock, and pistol grip, interchangeable handguard halves, an adjustable dual-aperture rear sight that corrects for both windage and elevation, a heavier barrel to increase accuracy, 1-in-7 rifling, a brass deflector to prevent ejected casings from hitting left-handed shooters, and an effective muzzle compensator to prevent muzzle climb during auto fire.
The M16A4 rifle is a modified M16A2 service rifle. An M1913 Rail Adapter System (RAS)
replaces the upper hand guards of the M16A2 and incorporates a removable rear-carrying handle. The rail adapter system and modified hand guards allow for the mounting of various accessories such as a modified M203 grenade launching system, high intensity flashlights, and IR laser target designators as well as optics.
In 2003 the U.S. Army issued limited numbers of the M-16A3 and M-16A4, which incorporate a rail mounting system similar to the M-4A1 Carbine. The M4 Carbine, a shortened version of the M-16A2 is replacing the longer standard rifle in selected military units.
This chart (from PS Magazine, January 2008) shows the differences in Models M16A1, M16A2 and M16A4:
The world wide popularity of the M16 family of rifles has created a demand for the firearms, parts, and accessories. As of 2008, these companies supply the largest numbers of rifles for the military, law enforcement, and civilian markets:
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