M16 5.56mm Rifle


The M14 was the Army's original choice to replace World War II-era M1 rifle, as well as the Browning Automatic Rifle. The M14 was an unhappy compromise weapon, that satisfied virtually no one, least of all the men for whom it was intended. General dissatisfaction with the M14 and numerous studies led the Army to the development of a light weight weapon capable of firing a burst of small caliber bullets with a controlled dispersion pattern. Unfortunately, the M14's follow-on initially fared little better.

The replacement for the M14 was originally designed by Eugene Stoner, of the ArmaLite Company, a division of the Fairchild Engine and Aircraft Corporation, as the AR-15 around 1956. The AR-10 was conceived by Eugene Stoner as a 7.62mm Basic infantry rifle in 1955. At that time the Army was considering replacements for the M1 Garand. The AR-10 was stunningly different than any previous design. It was produced with aircraft grade aluminum receivers, and therefore weighed less than 7 pounds. The stock and other furniture were plastic, while the T44 developed by the US Army and the T48 (the designation applied to the FN FAL rifle) were of wood. The configuration of the rifle itself, with its integral carrying handle and charging handle distinctively mounted within it, sparked intense curiosity. In the end, the AR-10 was not able to catch up, and eventually lost out to the T44 rifle, which was type designated as the M14 in 1959.

Based on the AR-10, Army officials asked Armalite to develop a smaller version of the AR-10 in 1956 as part of evaluations of what were then referred to as Small Caliber High Velocity (SCHV) rifles. The ensuing rifle was called the AR-15. Army analysis of battlefield statistics from World War I, World War II and Korea had shown that most kills from small arms occurred at ranges of less than 300 yards. This suggested that the military should seriously consider lighter weight, higher capacity weapons. Seeking a novel cartridge suitable for a smaller caliber assault rifle, Eugene Stoner approached Winchester Corporation. The result was a small but powerful .224 cartridge, which featured high-velocity, light weight, low recoil, and capable of penetrating a helmet per US Army specifications. Another round, developed by Remington Arms, the .222 Special was also utilized during the development of the AR-15.

In February 1958, the US Army Infantry Board at Fort Benning Georgia directed an evaluation of the Armalite AR-15 against the M14. The AR-15s used in the tests were described as prototype rifles developed by the Armalite Division of Fairchild Engine and Airplane Corporation, Los Angeles, California. They fire, selectively semiautomatic-automatic, a caliber .224 lead cored round developed by Winchester Western Division of Olin Mathieson Chemical Corporation or a caliber .222 lead cored round built to Armalite specifications by Remington Arms Corporation. The tests utilized both the Remington .222 Special cartridge and the Olin-Winchester .224E2 cartridge. The conclusions drawn from the evaluation were that the AR-15 was a potential replacement for the M14 rifle, the the AR-15 equipped with a bipod and hinged butt plate might provide a potential replacement for the M15 rifle, and that the penetration capability of either test round was significantly less than that of the control round and should be improved.

Production of the AR-15 rifle was licensed to to Colt Manufacturing Company in 1959. Early Colt AR-15s, their magazines, and their operators manuals were also marked with Armalite's name. The AR-15 was selectable for full and automatic fire. The AR-15 was to have had the same effective range as the M14 rifle, but it was most effective at a range of 215 yards (200 meters) or less.

The US Air Force completed tests of the AR-15 in January 1961. The US Air Force push, led by the Commander of US Air Force Strategic Air Command, was to replace the existing M2 carbines then in use by the USAF Air Police with the AR-15. The US Air Force attempted first to purchase 8,500 rifles in 1961, but had the funding denied. Not until August 1962 was the contract formally awarded to Colt. The last of the weapons were received in 1963 and the weapon was standardized the AR-15. With no modifications made to the basic Comerica offering, no military designation was applied to the weapon by any of the services.

The new rifle had the advantage from a military point of view of weighing one-fourth less than the M14, and the ammunition also was lighter, reducing the recoil against the soldier's shoulder and enabling a soldier to carry more rounds. As interest in the problems of counter-insurgency grew under the Kennedy administration in the early 1960s, the US military quietly bought several thousand AR-15s and sent them to Vietnam for testing in combat conditions, many of which were utilized by US Army Special Forces and US Navy SEALs.

A number of weapons also went to the Advanced Research Projects Agency (ARPA; which later became the Defense Advanced Research Projects Agency or DARPA), and through their testing, the weapon gained some measure acceptance through demonstration in combat. Colt brought the weapon to DARPA in 1962, which was at the time looking for a suitable replacement for various World War II-era infantry weapons supplied to the Army of the Republic of Vietnam. Through Project AGILE, ARPA purchased 1,000 AR-15s and issued them to combat troops in South Vietnam for field trials. The trials were intended to prove that the high-velocity 5.56mm round had satisfactory performance and that the weapon was suitable for the physical stature of the South Vietnamese infantry.

Soon reports began appearing of the lethality of the new rifle. Unofficial reports said the AR-15's light bullet, traveling at 3,300 feet per second, did cartwheels as it penetrates living flesh. The round was said to cause highly lethal wounds that looked like anything but a caliber .22 hole, according to the US magazine Army in August 1963. The subsequent ARPA report, which documented this apparent lethality of the AR-15, was instrumental in motivating the Secretary of Defense to reconsider the Army's decision and eventually adopt a modified AR-15 as the US military individual weapon of choice.

Ironically, the gruesome after action reports from the AGILE tests, which were used as evidence of the weapon's adequate performance in combat, were never recreated in a laboratory setting despite attempts both in the United States and in the United Kingdom. Reports from the field persisted, however. Two US Army doctors who evaluated AR-15 wounds at an Army hospital in South Vietnam in 1966 reported that while wounds inflicted at close range had small entrance and exit holes, those at larger ranges exhibited small entrance holes, but gaping exit wounds, devastated area of soft tissue and even bone, often with loss of large amounts of tissue, with disintegration of the bullet, and minute splattering of lead.

By 1963, the US Army had standardized a variant of the AR-15 featuring among other things a manual bolt closure device (referred to generally as a "forward assist"), which allowed the weapon's action to be closed manually, as the XM16E1. These weapons were authorized as the standard issue weapon for US Army Special Forces, Airborne, and Airmobile troops. Other elements of the US Army continued to be issued the M14. With the adoption of the XM16E1 nomenclature, AR-15s already in inventory were effectively retroactively assigned to the nomenclature XM16, though this was essentially a paper designation only.

The US Secretary of Defense, Robert McNamara at the time hoped that the M16 would be an interim acquisition, hoping for positive results from the Special Purpose Infantry Weapon (SPIW) program. Despite this, the Army ordered 85,000 rifles in 1963. An additional 35,000 were ordered in 1964, 100,000 in 1965, and 100,000 in 1966. As well as seeing action in Vietnam, the US intervention in the Dominican Republic in 1965 also saw the deployment of troops with the new rifle.

The adoption of the 5.56mm AR-15 type rifle for US Air Force use and limited US Army use in the early 1960s stimulated the interest of industry in developing other weapons in this caliber for military use. On 17 December 1964, the Chief of Staff of the Army directed a review and evaluation of Small Arms Weapons Systems (SAWS) either in being, or feasible for adoption within the time frame 1967-80. This evaluation included the existing standard system of small arms in the US Army: M14, M14E2, M60, and XMI6E1. The objective of this program was to develop data upon which to base a program for replenishment of stocks of small arms as the inventory drops below requirements, and/or replacement of current small arms with weapons of demonstrated superiority. The tests proved inconclusive, showing deficiencies with regards to US Army requirements in all the tested systems.

Although opposed by the US Army Ordnance Corps, which had developed the M14, the XM16E1 was formally type designated standard and adopted as the 5.56mm M16A1 rifle in 1965 and by 1966 it had become the military's basic service rifle. New production weapons without the forward assist, purchased by the US Air Force and US Navy, were to be designated M16. By 1966 it was in widespread use in Vietnam, with priority for the rifle going to units deploying to southeast Asia. Units in Europe and the United States retained the M14, or in some cases even reissued the M1 Garand for a period thereafter.

The M16 and M16A1 used a 5.56mm (.223 caliber) cartridge in 20- or later 30-round magazines. To compensate for the reduced size of the 5.56mm bullet, the AR-15 designers had increased the velocity of the bullet so that it would have an adequate range and the flat trajectory needed for accurate aiming. The bullet had a muzzle velocity (velocity on leaving the barrel of the gun) of 980 meters per second as compared to 870 meters per second for the M14 rifle and 720 meters per second for the Soviet AK-47 rifle. At a range of 100 meters the velocities of the 3 bullets were 830, 800, and 630 meters per second respectively.

The M16 was called the "black rifle" and "Mattel toy" thanks to its appearance and construction. Suggestions that any part of the weapon was ever made by the Mattel toy company, however, have no basis in fact. Troops liked the light weight, but complained about insufficient range, lethality, and in some cases durability. While the M16 had been marketed as virtually "maintenance free," poor maintenance instructions (or even no instructions), a complete lack of cleaning kits initially, and jungle climate together with the direct gas system caused trouble. Its high rates of fire in the jungle environment had a larger impact on increasing American morale than on actually inflicting enemy casualties.

The move to high-velocity 5.56mm was also subsequently adopted by the Israelis, the Soviets, and NATO allies. By 1978 the rifle had been exported to 21 countries and was being produced under licence in another three, with various other 5.56 mm rifles in production elsewhere.

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