M-16 Rifle

The M16 entered United States Army service in 1964 for deployment in Vietnam. The M16 became the standard US Rifle in the Vietnam War by 1969,^[3] replacing the M14 rifle in that role. The US Army retained the M14 in CONUS, Europe, and South Korea until 1970. Since the Vietnam War, the M16 rifle family has been the primary infantry rifle of the U.S. military. With its variants, it has been in use by 15 NATO countries, and is the most produced firearm in its caliber.

The M16 is a lightweight, 5.56 mm caliber, air-cooled, gas-operated, magazine-fed assault rifle, with a rotating bolt, actuated by direct impingement gas operation. The rifle is made of steel, aluminum, and composite plastics.

The U.S. Air Force’s rifle, the M16, and the United States Marines and Army rifle, the XM16E1, were the first versions of the M16 rifle fielded. Soon, the Army standardized the XM16E1 as the M16A1 rifle, an M16 with a forward assist feature requested by the Army. All of the early versions were chambered to fire the M193/M196 cartridge in the semi-automatic and the automatic firing modes. This occurred in the early 1960s, with the Army issuing it in late 1964.^[4] Commercial AR-15s were first issued to Special Forces troops in spring of 1964.^[5]

The M16A2 rifle entered service in the 1980s, chambered to fire the standard NATO cartridge, the Belgian-designed M855/M856 cartridge.^[4] The M16A2 is a select-fire rifle (semi-automatic fire, three-round-burst fire) incorporating design elements requested by the Marine Corps:^[4] an adjustable, windage rear-sight; a stock 5/8-inch longer; heavier barrel; case deflector for left-hand shooters; and cylindrical hand guards.^[4] The fire mode selector is on the receiver’s left side. The M16A2 is still the primary rifle in the U.S. Navy, Coast Guard, Air Force, and still is in heavy use in the Army and Marine Corps.

The M16A3 rifle is an M16A2 rifle with an M16A1’s fire-mode control (semi-automatic fire, automatic fire) used only by the U.S. Navy.

The M16A4 rifle was standard issue for the United States Marine Corps in Operation Iraqi Freedom; it replaced the M16A2 in front line units. In the U.S. Army, the M16A2 rifle is being supplemented with two rifle models, the M16A4 and the M4 Carbine, as the standard issue Assault rifle. The M16A4 rifle has a flat-top receiver developed for the M4 Carbine, a handguard with four Picatinny rails for mounting a sight, laser, night vision device, forward handgrip, removable handle, and a flashlight.

The M16 rifle is principally manufactured by the Colt and the Fabrique Nationale de Herstal arms companies, with the variant rifles made elsewhere in the world. Versions for the U.S. military have also been made by H & R Firearms^[6] General Motors Hydramatic Division^[7] and most recently by Sabre Defence Industries. The semi-automatic versions of the M16 rifle, generally called the “AR-15″ (Colt bought the nomenclature from Armalite), are popular, recreational shooting rifles, with versions manufactured by other small and large manufacturers in the U.S.

History

The AR-15 was first adopted in 1962 by the United States Air Force (USAF), ultimately receiving the designation M16. The U.S. Army began to field the XM16E1 en masse in 1965 with most of them going to the Republic of South Vietnam, and the newly organized & experimental Airmobile Divisions, the 1st Air Cavalry Division in particular. The U.S. Marine Corps in South Vietnam also experimented with the M16 rifle in combat during this period. The XM16E1 was standardized as the M16A1 in 1967. This version remained the primary infantry rifle of US forces in South Vietnam until the end of the war in 1975, and remained with all US military ground forces after it had replaced the M14 service rifle in 1970 in CONUS (Continental US), Europe (Germany), and South Korea; when it was supplemented by the M16A2. During the early 1980s a roughly standardized load for this ammunition was adopted throughout NATO (see: 5.56×45mm NATO).

The M16A3 is a fully-automatic variant of the M16A2, issued primarily within the United States Navy. The M16A2, in turn, is currently being supplemented by the M16A4, which incorporates the flattop receiver unit developed for the M4 Carbine, and Picatinny rail System. M16A2 are still in stock with the U.S. Army and Marine Corps, but are used primarily by reserve and National Guard units as well as by the U.S. Air Force.

Project SALVO

In 1948, the Army organized the civilian Operations Research Office (ORO), mirroring similar operations research organizations in the United Kingdom. One of their first efforts, Project ALCLAD, studied body armor and the conclusion was that they would need to know more about battlefield injuries in order to make reasonable suggestions.^[8] Over 3 million battlefield reports from WWI and WWII were analyzed and over the next few years they released a series of reports on their findings.^[8]

The conclusion was that most combat takes place at short range. In a highly mobile war, combat teams ran into each other largely by surprise; and the team with the higher firepower tended to win. They also found that the chance of being hit in combat was essentially random — that is, accurate “aiming” made little difference because the targets no longer sat still. The number one predictor of casualties was the total number of bullets fired.^[8] Other studies of behavior in battle revealed that many U.S. infantrymen (as many as 2/3) never actually fired their rifles in combat. By contrast, soldiers armed with rapid fire weapons (such as submachine guns) were much more likely to have fired their weapons in battle.^[9] These conclusions suggested that infantry should be equipped with a fully-automatic rifle of some sort in order to increase the actual firepower of regular soldiers. It was also clear, however, that such weapons dramatically increased ammunition use and in order for a rifleman to be able to carry enough ammunition for a firefight they would have to carry something much lighter.

Existing rifles were poorly suited to real-world combat for both of these reasons. Although it appeared the new 7.62 mm T44 (precursor to the M14) would increase the rate of fire, its heavy 7.62 mm NATO cartridge made carrying significant quantities of ammunition difficult. Moreover, the length and weight of the weapon made it unsuitable for short range combat situations often found in jungle and urban combat or mechanized warfare, where a smaller and lighter weapon could be brought to bear faster.

These efforts were noticed by Colonel René Studler, U.S. Army Ordnance’s Chief of Small Arms Research and Development. Col. Studler asked the Aberdeen Proving Ground to submit a report on the smaller caliber weapons. A team led by Donald Hall, director of program development at Aberdeen, reported that a .22 inch (5.56 mm) round would have performance equal to larger rounds in most combat.^[10] With the higher rate of fire possible due to lower recoil it was likely such a weapon would inflict more casualties on the enemy. His team members, notably William C. Davis, Jr. and Gerald A. Gustafson, started development of a series of experimental .22 (5.56 mm) cartridges. In 1955, their request for further funding was denied.

A new study, Project SALVO, was set up to try to find a weapon design suited to real-world combat. Running between 1953 and 1957 in two phases, SALVO eventually suggested that a weapon firing four rounds into a 20-inch (508 mm) area would double the hit probability of existing semi-automatic weapons.

In the second phase, SALVO II, several experimental weapons concepts were tested. Irwin Barr of AAI Corporation introduced a series of flechette weapons, starting with a shotgun shell containing 32 darts and ending with single-round flechette “rifles”. Winchester and Springfield offered multi-barrel weapons, while ORO’s own design used two .22, .25 or .27 caliber bullets loaded into a single .308 Winchester or .30-06 cartridge.

Eugene Stoner

Meanwhile testing of the 7.62 mm T44 continued, and Fabrique Nationale also submitted their new FN FAL via the American firm Harrington & Richardson as the T48. However, the results of the testing were apparently already a forgone conclusion; the T44 was selected as the new battle rifle for the U.S. Army (rechristened the M14) despite a strong showing by the T48.

Acceptance of the M14 did not occur before a newcomer entered the contest. In 1954, Eugene Stoner of the newly-formed ArmaLite helped develop the 7.62 mm AR-10. Springfield’s T44 and similar entries were conventional rifles using wood for the “furniture” and otherwise built entirely of steel using mostly forged and machined parts. ArmaLite was founded specifically to bring the latest in designs and alloys to firearms design, and Stoner felt he could easily beat the other offerings.

Stoner’s AR-10 was radical for its day. The receiver was made of forged and milled aluminum alloy instead of steel. The barrel was mated to the receiver by a separate hardened steel extension to which the bolt locked. This allowed a lightweight aluminum receiver to be used while still maintaining a steel-on-steel lockup. The bolt was operated by high-pressure combustion gases taken from a hole in the middle of the barrel directly through a tube above the barrel to a cylinder created in the bolt carrier with the bolt carrier itself acting as a piston. Traditional rifles located this cylinder and piston close to the gas vent. The stock and grips were made of a glass-reinforced plastic shell over a rigid foam plastic core. The muzzle brake was fabricated from titanium. Over Stoner’s objections, various experimental composite and ‘Sullaloy’ aluminum barrels were fitted to some AR-10 prototypes by ArmaLite’s president, George Sullivan. The Sullaloy barrel was made entirely of heat-treated aluminum, while the composite barrels used aluminum extruded over a thin stainless steel liner.

Meanwhile the layout of the weapon itself was also somewhat different. Previous designs generally placed the sights directly on the barrel, using a bend in the stock to align the sights at eye level while transferring the recoil down to the shoulder. This meant that the weapon tended to rise when fired making it very difficult to control during fully-automatic fire. The ArmaLite team used a solution previously used on weapons such as the German FG 42 and Johnson light machine gun; they located the barrel in line with the stock, well below eye level, and raised the sights to eye level. The rear sight was built into a carrying handle over the receiver.

The AR-10 was a very advanced design for its time. Despite being over 2 lb (0.9 kg) lighter than the competition, it offered significantly greater accuracy and recoil control. Two prototype rifles were delivered to the U.S. Army’s Springfield Armory for testing late in 1956. At this time, the U.S. armed forces were already two years into a service rifle evaluation program, and the AR-10 was a newcomer with respect to older, more fully-developed designs. Over Stoner’s continued objections, George Sullivan had insisted that both prototypes be fitted with composite aluminum/steel barrels. Shortly after a composite barrel burst on one prototype in 1957, the AR-10 was rejected. The AR-10 was later produced by a Dutch firm, Artillerie Inrichtingen, and saw limited but successful military service with several foreign nations such as Sudan, Guatemala, and Portugal. Portugal deployed a number of AR-10s for use by its airborne (Caçadores Pára-quedista) battalions, and the rifle saw considerable combat service in Portugal’s counter-insurgency campaigns in Angola and Mozambique.^[11] Some AR-10 rifles were still in service with airborne forces serving during the withdrawal from Portuguese Timor in 1975.

CONARC

In 1957, a copy of Gustafson’s funding request from 1955 found its way into the hands of General Willard G. Wyman, commander of the U.S. Continental Army Command (CONARC). He immediately put together a team to develop a .22 caliber (5.56 mm) weapon for testing. Their finalized request called for a select-fire weapon of 6 pounds (2.7 kg) when loaded with 20 rounds of ammunition. The bullet had to penetrate a standard U.S. steel helmet, body armor, or a 0.135 inch (3.4 mm) steel plate and retain a velocity in excess of the speed of sound at 500 yards (460 m), while equaling or exceeding the “wounding” ability of the .30 Carbine.^[8][12]

Wyman had seen the AR-10 in an earlier demonstration, and impressed by its performance he personally suggested that ArmaLite enter a weapon for testing using a 5.56 mm cartridge designed by Winchester.^[8] Their first design, using conventional layout and wooden furniture, proved to be too light. When combined with a conventional stock, recoil was excessive in fully automatic fire. Their second design was simply a scaled-down AR-10, and immediately proved much more controllable. Winchester entered a design based loosely on their M1 Carbine, and Earle Harvey of Springfield attempted to enter a design, but was overruled by his superiors at Springfield, who refused to divert resources from the T44.

In the end, ArmaLite’s AR-15 had no competition. The lighter round allowed the rifle to be scaled down, and was smaller and lighter than the previous AR-10. The AR-15 weighed only around 5.5 lb (2.5 kg) empty, 6 lb (2.7 kg) loaded (with a 20 round magazine).

During testing in March 1958, rainwater caused the barrels of both the ArmaLite and Winchester rifles to burst, causing the Army to once again press for a larger round, this time at 0.258 in (6.6 mm). Nevertheless, they suggested continued testing for cold-weather suitability in Alaska. Stoner was later asked to fly in to replace several parts, and when he arrived he found the rifles had been improperly reassembled. When he returned he was surprised to learn that they too had rejected the design even before he had arrived; their report also endorsed the 0.258 in (6.6 mm) round. After reading these reports, General Maxwell Taylor became dead-set against the design, and pressed for continued production of the M14.

Not all the reports were negative. In a series of mock-combat situations testing the AR-15, M14 and AK-47, the Army found that the AR-15’s small size and light weight allowed it to be brought to bear much more quickly, just as CONARC had suggested. Their final conclusion was that an 8-man team equipped with the AR-15 would have the same firepower as a current 11-man team armed with the M14. They also found that the AR-15, as tested, was more reliable than the M14, suffering fewer stoppages and jams in tests where thousands of rounds were fired.

At this point, Fairchild had spent $1.45 million in development expenses, and wished to divest itself of its small-arms business. Fairchild sold production rights for the AR-15 to Colt Firearms in December 1959, for only $75,000 cash and a 4.5% royalty on subsequent sales. In 1960, ArmaLite was reorganized, and Stoner left the company.

M16 adoption

Curtis LeMay viewed a demonstration of the AR-15 in July 1960. He immediately ordered 8,500 for defense at Strategic Air Command airbases, later rescinded by Defense Secretary Robert McNamara. Colt Industries also approached the Advanced Research Projects Agency (ARPA), who bought 1,000 rifles for use by South Vietnamese troops in the early summer of 1962. American special operations units and advisers working with the South Vietnamese troops filed battlefield reports lavishly praising the AR-15 and the stopping effectiveness of the 5.56 mm cartridge, and pressed for its adoption.

U.S. Secretary of Defense Robert McNamara now had two conflicting views: the ARPA report favoring the AR-15 and the Pentagon’s position on the M14. Even President John F. Kennedy expressed concern, so McNamara ordered Secretary of the Army Cyrus Vance to test the M14, the AR-15 and the AK-47. The Army’s test report stated only the M14 was suitable for Army use, but Vance wondered about the impartiality of those conducting the tests. He ordered the Army Inspector General to investigate the testing methods used, who reported that the testers showed favor to the M14.

Secretary Robert McNamara ordered a halt to M14 production in January 1963, after receiving reports that M14 production was insufficient to meet the needs of the armed forces. Secretary McNamara had long been a proponent of weapons program consolidation among the armed services. At the time, the AR-15 was the only rifle that could remotely fulfill a requirement of a ‘universal’ infantry weapon for issue to all services. McNamara ordered the weapon be adopted unmodified, in its current configuration, for immediate issue to all services, despite receiving reports noting several deficiencies with the M16 as a service rifle, including the lack of a chrome-lined bore and chamber, the 5.56 mm projectile’s instability under Arctic conditions, and the fact that large quantities of 5.56 mm ammunition required for immediate service were not available. In addition, the Army insisted on the inclusion of a forward assist plunger to help push the bolt into battery in the event that a cartridge failed to seat in the chamber through fouling or corrosion. The original Armalite already had a chrome-lined chamber to prevent corrosion.^{[citation needed]} Colt on the other hand, had argued the rifle was a ’self-cleaning’ design, requiring little or no maintenance. Colt, Eugene Stoner, and the U.S. Air Force believed that a forward assist needlessly complicated the rifle, adding about $4.50 to its procurement cost with no real benefit. As a result, the design was split into two variants: the Air Force’s M16 without the forward assist, and for the other service branches, the XM16E1 with the forward assist.

In November 1963, the Army ordered 85,000 XM16E1s for experimental use, and the Air Force ordered another 19,000 M16s.^[8] Meanwhile, the Army carried out another project, the Small Arms Weapons Systems (SAWS), on general infantry firearm needs in the immediate future. They highly recommended the immediate adoption of the weapon, so much so that they started referring to it as the M16. Later that year the Air Force officially accepted their first batch as the United States Rifle, Caliber 5.56 mm, M16.

The Army immediately began to issue the XM16E1 (re-named M16A1 on its adoption) to infantry units, and the rifle was initially delivered without adequate cleaning supplies or kit. Moreover, the Army’s inability to deliver 5.56 mm ammunition meeting quantity and velocity specifications led to a change in powder specification for the 5.56 mm cartridge. The change was made without testing the modified ammunition in the rifle under service conditions; the newly-specified 5.56 ammunition increased the cyclic rate of fire, increasing wear on parts, and the new gunpowder’s burning characteristics increased fouling in the M16 rifle.

When the XM16E1 reached Vietnam with U.S. troops in March 1965, reports of jamming and malfunctions in combat immediately began to surface. Although the M14 featured a chrome-lined barrel and chamber to resist corrosion in combat conditions (a danger learned from WWII Pacific theatre combat experience), neither the bore nor the chamber of the M16/XM16E1 was chrome-lined. Several documented accounts of troops killed by enemy fire with jammed rifles broken-down for cleaning eventually brought a Congressional investigation.^{[citation needed]} Later investigations also cast doubt on the veracity of the original 1962 reports of the alleged stopping effectiveness of the 5.56 mm bullet, as well as criticism of inadequate penetration (in comparison to the Soviet 7.62×39mm round) when firing at enemy personnel through light cover.^{[citation needed]}

On February 28, 1967, the XM16E1 was standardized as the M16A1. Major revisions to the design followed. The rifle was finally given a chrome-lined chamber (and later, the entire bore) to eliminate corrosion and stuck cartridges, and the rifle’s recoil mechanism was re-designed to accommodate Army-issued 5.56 mm ammunition. Rifle cleaning tools and powder solvents/lubricants were issued. Intensive training programs in weapons cleaning were instituted, and a comic book style manual was circulated among the troops to demonstrate proper maintenance.^[8] The reliability problems of the M16 diminished quickly, although the rifle’s reputation continued to suffer.^[8] Moreover, complaints about the inadequate penetration and stopping power of the 5.56 mm cartridge persisted throughout the Vietnam conflict.^{[citation needed]}

According to a February 1968 Department of Defense report the M16 rifle achieved widespread acceptance by U.S. troops in Vietnam. Only 38 of 2100 individuals queried wanted to replace the M16 with another weapon. Of those 38, 35 wanted the CAR-15 (a shorter version of the M16) instead.^[13]

NATO Standards

In March 1970, the Pentagon shocked other NATO nations by stating that all NATO forces would eventually adopt the 5.56×45mm cartridge. The British military was highly vocal in voicing its anger after adopting the 7.62mm NATO cartridge over their .280 caliber (7.1 mm) nearly 20 years earlier. The British were now being told that the U.S. recognized the need for such a caliber of firearm after all, and was willing to start the NATO standardization of a lighter round.

By the middle of the 1970s, other armies were also looking at an M16-style weapon. A NATO standardization effort soon started, and tests of various rounds were carried out starting in 1977. The U.S. offered their original design, the M193, with no modifications, but there were serious concerns about its penetration in the face of the wider introduction of body armor. The British offered a modified 5.56 mm round, using a longer and thinner bullet of 4.85 mm. The round had somewhat better ballistics and considerably better penetration, able to reach 600 m and meet their requirements for a squad automatic weapon (light machine gun). The Germans proposed a new 4.7 mm caseless round, which was considerably lighter while offering similar ballistics to the original U.S. design. However, there was distrust in the caseless system due to the possibility of cook off. A final design was offered by the Belgians. Their SS109 round was based on the U.S. cartridge but included a new bullet design, with the same 5.56 mm caliber, but with a small steel tip added to improve penetration.

Testing soon showed that the British and Belgian designs were roughly equal, both outperforming the original U.S. design. In order to get full performance from tracer versions of the SS109, however, barrels would have to use different rifling. Existing 12 in (300 mm) twist barrels reduced the effective range of the SS109 to 90 meters due to lack of stability. While the ideal twist rate for the SS109 projectile is 9 in (229 mm), a 7 in (180 mm) twist rate was chosen to stabilize the much longer L110 tracer. This tracer was designed to complement the SS109’s ballistic performance. The M196 tracer (complement to the M193 ball round) had a burn-out range of 450 meters where the L110 tracer was bright to 800 meters. In the end the Belgian round was chosen. The U.S. Marine Corps was first to adopt the round with the M16A2, introduced in 1982. This was to become the standard U.S. military rifle. The NATO 5.56×45mm standard ammunition produced for U.S. forces is designated M855 for the ball round using an SS109 type projectile and M856 for the tracer using the L110 type projectile.

Total worldwide production of M16-style weapons since the design’s inception has been approximately 8 million.^[2]

http://en.wikipedia.org/wiki/M16_rifle