M16 (rifle)

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M16 is the US Military designation for the Armalite AR-15, an assault rifle which fires NATO standard 5.56 mm ammunition (STANAG 4172). This has been the primary infantry rifle of the United States military since 1967, and is in use by 15 NATO countries. It has been the most produced assault rifle of its caliber, and is favored for its reliability and ease of operation. Despite early failures, it is often recognized as the best assault rifle of its time period, and is the paradigm for assault rifles today. It is primarily manufactured by Colt and Fabrique Nationale, with variants produced by numerous countries around the world. The semiautomatic version, the AR-15 is a popular recreational firearm in the United States.

Contents

History

In the 1950s various military forces were studying the impact of the German StG44, the world's first true assault rifle which had seen limited service with the Wehrmacht in the final stages of WWII. The basic concept of this weapon was to reduce the power of the rounds in order to control recoil, increase the magazine size, and making up for the lack of range and accuracy by allowing the rifle to be fired in either semiautomatic or fully automatic mode. This dramatically increased the overall firepower of a squad equipped with such weapons; a late war German eight-man squad with StG44's and a single MG42 general purpose machine gun had roughly the same firepower as three or four US or British army squads.

The British immediately turned to the design of their own assault rifle, in order to replace their outdated WWI-vintage bolt-action Lee-Enfield. In 1951, the Ministry of Defence selected a .280 cal. (7 mm) round with somewhat higher power than the StG44's "Kurz", fired from a compact weapon, the Enfield EM-2. The US, however, was slower to see the need for a new rifle as they had a considerable surplus of the semi-automatic .30-'06 M1 Garand.

The Garand was by no means a perfect weapon, however, and several experiments were carried out to improve it. These centered around adding full-automatic capabilties and replacing the limited capacity en bloc clips with a box magazine holding 20 rounds. Winchester, Remington, and Springfield Armory's own John Garand offered different conversion designs. Garand's design, the T20, was the most popular, and T20 prototypes served as the basis for a number of Springfield test rifles from 1945 through the early 1950s. Earle Harvey of Springfield Armory designed a completely different rifle, the T25, for the new .30 Light Rifle cartridge. The latter was based upon .30-'06 brass cut down to the length of the .300 Savage cartridge. The .30 Light Rifle eventually evolved into the 7.62mm NATO and the commercial .308 Winchester round. In the background, Lloyd Corbett was tasked with developing .30 Light Rifle conversions for the M1 rifle and later the T20 prototypes. After a series of prototype designs, the T44 surfaced.

When it was learned that the US would be introducing the .308 Winchester round, the British raised serious concerns. They pressed for the adoption of their .280 round instead, saying that the .308 round would be uncontrollable in fully-automatic fire. Studler, backed into a corner, became increasingly dedicated to the .30 Light Rifle, and shrugged off any suggestion that the recoil would be a problem. In the end, the debate was settled in unlikely fashion when the Canadian forces suggested they would be happy to use the .280, but only if the US did as well. It was clear this would not happen, and the .308 became the 7.62 x 51 mm NATO round.

Project SALVO

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

Their basic conclusion was, as was found by the Germans and British before them, that the vast majority of combat takes place at short ranges. In a highly mobile war combat teams ran into each other largely by surprise, and the team with the higher firepower tended to win every time. 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.

These conclusions suggested that infantry should be equipped with a fully automatic rifle of some sort, in order to increase the rate of fire. However, it was also clear that such weapons dramatically increased ammunition use, in order for a rifleman to be able to carry enough ammunition for a firefight, they would have to carry something much lighter.

For both of these reasons, existing rifles were poorly suited to real-world combat. Although it appeared the new T44 would increase the rate of fire, its heavy ammunition made carrying enough of it a real problem. Moreover the length and weight of the gun meant it was not really suitable for short range combat, where a smaller and lighter weapon could be brought to bear much more quickly.

These efforts had not gone unnoticed by Ren Studler, US Army Ordnance's Chief of Small Arms Research and Development. He was upset about the civilian agency that was treading on "his" turf, and started an effort to support the "full power" round developed for the T25. In the end, he asked the Aberdeen Proving Ground to submit a report on the smaller caliber weapons.

This plan backfired when his assigned research lead, Donald Hall, found that a .22 in (5.59 mm) round would have equal performance to larger rounds in most combat situations. 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 G.A. Gustafson, started development of a series of experimental .224 in (5.69 mm) rounds. 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 in (0.5 m) area would have 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 introduced a series of flechette weapons, starting with a shotgun shell containing 32 darts and ending with single-round flechette "rifles". Winchester and Springfield offer multi-barrel weapons, while ORO's own design used two .22, .25 or .27 bullets loaded into a single .308 or .30-06 cartridge.

Eugene Stoner

Meanwhile testing of the T44 continued, and Fabrique Nationale via the American firm of Harrington & Richardson also submitted their new FN FAL into testing 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 US Army.

But this did not occur before a newcomer seriously upset the contest. In 1954, Eugene Stoner of the newly-formed ArmaLite started development of the AR-10. Springfield's T44 and similar entries were conventional in every meaning of the term, using wood for the "furniture" and otherwise built entirely of steel. 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 design was radical, to say the least. The barrel was composite, consisting of a thin steel liner carrying the rifling, inside an aluminum alloy tube giving it strength. The receiver was made of milled aluminum instead of steel. The barrel liner extended into the receiver area where it met the bolt to provide a steel-on-steel lock for the mechanism. The bolt was operated by gases vented from the front of the barrel directly onto a cam on the bolt in the receiver, as opposed to the traditional method of using a long rod to push it. All of the furniture (the stock and grips) were made of plastic instead of wood, and even the flash hider was lightened by making it out of titanium.

Meanwhile the layout of the gun itself was also radically changed. Typical designs placed the sights directly on the barrel, using a bend in the stock to transfer the recoil to the shoulder. However this meant that the gun wanted to rise when fired, making it very difficult to control. Stoner's solution to this problem was to place the barrel in line with the stock, well below eye level, and then raise the sights up. The rear sight's carrier doubled as a convenient carrying handle.

The AR-10 was by far the most advanced design in the world at the time. At over two pounds (900 g) lighter than the competition and with much better recoil control, it should have easily won the contest. However, it was entered late and somewhat rushed, and the odd layout found few followers among the traditionalist big-round players. When a barrel burst in testing, the AR-10 was largely written off.

CONARC

In 1957, a copy of Gustafson's funding request from 1955 found its way into the hands of General Willard Wyman, commander of the US Continental Army Command (CONARC). He immediately put together a team to develop a .22 caliber 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 US steel helmet, body armor, or a 0.135 inch (3.4 mm) steel plate at 500 yards (460 m), while equaling or exceeding the "wounding" ability of the .30 Carbine.

Having seen the AR-10 earlier, Wyman personally suggested that ArmaLite enter a weapon for testing. Stoner was working on a newer version of the AR-10 (the AR-16), but others at the company took up the challenge. Their first design, using conventional layout and wooden furniture, proved to be too light. When combined with a conventional stock, recoil was again a problem even with the light rounds. Their second design was simply a scaled-down AR-10, and immediately proved to be much more successful. Winchester entered a design based 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 really had no competition. The lighter round allowed it to be scaled down even smaller than the AR-10, and even after replacing the barrel with a simpler all-steel one, it was still well over a pound (450 g) lighter than the Winchester at 2.89 kilograms empty, about 3.5 kg loaded.

Its only major problem was that it wasn't fully developed before Army testing began nine months later on March 31st, 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 .258 in. 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 "surprisingly" suggested the .258 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, Army testing 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 soldier team equipped with the AR-15 would have the same firepower as a current 11 soldier team armed with the M14. They also found that the AR-15 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 there was no end in sight. 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

A demonstration of the AR-15 was made to Curtis LeMay in June 1960. He immediately ordered 8,500 for defense at Strategic Air Command airbases. Colt Industries also approached the Advanced Research Projects Agency (ARPA), who bought 1000 rifles for use by South Vietnamese troops in the early summer of 1962. American special operations units working with the South Vietnamese troops filed remarkable battlefield reports, pressing for its immediate adoption.

US 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 undue favor to the M14.

McNamara ordered a halt to M14 production in January 1964. In November, the Army ordered 85,000 XM16E1s for experimental use, and the Air Force ordered another 19,000. 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 Air Force M16s were different from the Army XM16E1s, which had a forward assist, as described below. The Air Force M16s were basicly lightly modified AR-15s.

When the M14 reached Vietnam with US troops in 1965 its flaws were instantly recognized. It was far too cumbersome and too heavy to use effectively in a close-quarters jungle environment, and the heavy ammunition meant only small quantities were carried on patrol. The fully automatic fire quickly demonstrated itself as useless, as the British had suggested, and the rifles were eventually delivered locked in semi-automatic. In the end the Army had spent a considerable amount of time and money switching from one semi-automatic weapon to another, and it appeared this happened largely due to internal politics.

Meanwhile the troops desperately tried to increase their own firepower in the face of the Viet Cong's Soviet-designed AK-47s. They took to scrounging any weapon they could find, the pre-WWII Tommy gun became particularly well-used. The XM16E1 was being introduced in increasing numbers, but quickly gained a bad reputation.

With the XM16E1 the Pentagon had demanded a change in the cartridge's propellant from the coarse-grained Improved Military Rifle (IMR) to the finer grained "ball" powder, which increased the automatic firing rate but also increased fouling of the bore and consequently caused the rifle to jam. To correct this, a "forward assist" plunger device to close the bolt in case of a misfeed was added. Colt, the Air Force, the Marine Corps and Eugene Stoner all agreed this device needlessly complicated the rifle and added about $4.50 to its procurement cost with no real benefit, but after another three years the Army ordered 840,000 of this version on February 28th, 1967. The version became known as the M16A1.

Colt had oversold the M16's reliability during testing, to the point where they claimed it never had to be cleaned. While this may have been true with the original IMR powder the rifle was developed with, it was not the case with the more finely-grained, faster-burning ball powder that was considerably "dirtier". The direct impingement gas operating system, adapted from the Swedish Ljungman AG42B and the French MAS 49 series of rifles, used an open tube along the top of the barrel that vented gas back directly onto the front of the bolt. In normal designs, the gas pressed on a spring-loaded operating rod which pushed back the bolt or bolt carrier, so the system was fairly "clean". The rod was removed in the M16 to lighten it, and as a result dirt in the mechanism would be recycled into the chamber and slowly build up.

Making matters worse, troops were told the weapon required no cleaning because of its space age construction, and had not been supplied with cleaning kits. In the field the guns started jamming all the time. Soldiers often derisively referred to them as "toy guns" and used the catch phrase "You can tell it's Mattel" when one malfunctioned. This later blossomed into an urban legend that the first M16s were actually manufactured by the toy giant.

The M16 debate once again took off, both in the Army and in Washington, DC. Stoner's latest design, a family of weapons known as the Stoner 63, were sent to Vietnam for testing, while the SPIW flechette test weapon program was re-activated.

Luckily cooler heads prevailed. Cleaning kits were quickly produced, and a comic book was circulated among the troops to demonstrate proper maintenance. The reliability problems disappeared almost overnight, although the reputation did not. This did not appear to be true for the North Vietnamese troops, however, who started to use the rifle whenever one could be found.

A major change that came with the M16A1 was the introduction of hard chrome plating in the chamber, and some time later, the barrel as well. This dramatically decreased wear and corrosion problems, a change that had been suggested in the original SALVO tests. After its rocky start, the M16 has since proven itself to be one of the most reliable combat rifles ever produced. By the end of 1967, the troops, when asked, would only trade in their M16s for the XM177, a carbine version of the same weapon.

The lightweight round was likewise a matter of much debate in the rifle community. The "big round" concept refused to die for many years, and calls for an increase in caliber continued into the 1980s. Much of the debate centered on the Soviet Union's use of a larger StG44-style round, the 7.62 x 39 mm, cut down from their wartime 7.62 x 54R "full power" design. The debate ended for good when in the early 1970s the USSR introduced their own small round, one even smaller than the M16 at only 5.45 x 39 mm. Apparently SALVO had the right idea all along.

NATO standardization

In March 1970, the Pentagon shocked other NATO nations by stating all US forces assigned to NATO would be equipped with the M16A1. The British military was highly vocal in voicing its anger after being thrashed by American Ordnance personnel into adopting the 7.62 mm NATO round because their .280 caliber round wasn't effective enough nearly twenty years earlier. Now they were being told the US didn't care about NATO standardization after all, and that they were going to select an even lighter round.

But 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 US 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 introduced a modified 5.56 mm round, using a longer and thinner bullet of 4.85 mm, mounted in the existing US cartridges. The round had somewhat better ballistics, and considerably better penetration, able to reach 600 m and meet their requirements for a squad automatic weapon (small machine gun). The Germans introduced a new 4.7 mm caseless round, which was considerably lighter while offering similar ballistics to the original US design. However, there was considerable distrust of the system due to the possibility of "cook off". A final design was offered by the Belgians, the SS-109, a new round also based on the US cartridge and a new bullet with the same 5.56 mm caliber, but with a small tip of tungsten to improve penetration.

Testing soon showed that the British and Belgian designs were roughly equal, both outperforming the original US design. In order to get full performance from the SS-109, however, the barrels would have to use a 1-in-7 twist in the rifling, and in the existing 1-in-9 it offered almost no advantage over the M193. In the end it appears that the Belgian round was an easier sell to the US Army, even though either round would require all-new rifles. The resulting M16A2, introduced in 1982, has been the standard US military rifle since then.

After all of the debate, the M16 is still considered to be one of the best combat rifles ever produced. Total world-wide production is about 8 million.

Future replacement?

Throughout the 1970s the Army experimented with various materials to replace the brass casings. Brass has a number of features that make it almost ideal for a cartridge, including low-friction against steel which made it easier to extract, and its ability to carry away a considerable amount of heat from the weapon and thereby keep it cooler. However brass is also heavy and expensive, replacing it would lower both the cost and weight of the ammunition.

Aluminum and steel were popular materials for complete rounds, and AAI successfully developed a plastic blank. However none of these materials ever entered production for one reason or another. Completely caseless ammunition was also studied on several occasions, notably the German 4.7 mm designs, but issues with reliability and "cook off" were never completely solved.

Later in the 1980s the Advanced Combat Rifle program was run to find a replacement for the M16. The Army was pressing for a 100% increase in the ability for infantry to hit their targets, in the same way that SALVO had aimed to increase effectiveness by 100% through increased rate of fire.

Colt entered a modified M16A2 known as the Colt ACR, which used duplex rounds, used a system that lowered recoil by 40% to allow better repeating shots, and added a 3.5x scope. The Steyr ACR used new flechette ammunition that was nominally called 5.56 mm, with a very high 4750 ft/s (1450 m/s) muzzle velocity. Other variants experimented with caseless ammunition technologies as well.

Although they all offered some improvement, none came close to the benchmark set for the testing.

More recently the Army has started the XM8 system project for a radically improved weapon. However, the program has been shelved in favor of an open competition for what is now known as OICW Increment 1. (Increment 2 is the stand-alone airbursting grenade launcher known as the XM25, and Increment 3 will be the XM29, a weapon which combines the earlier two increments.)

Design

Missing image
Usafm16.jpg
Top drawing is of an A2 style rifle; Bottom drawing is of an A2 style rifle with A1 rear sights (As with the Diemaco C7)

The M-16 is made of aluminum alloy and plastics, except for the steel barrel and parts of the action. Early models were especially lightweight at 3.2 kg (7.5 lb), about 30% less than older 7.62 mm "battle rifles" of the 1950s and 1960s. It also compares very favourably with the 5 kg AK47. New models weigh more (8.5 lb or 3.9 kg) because of the "heavy" barrel used to increase accuracy. The rifle is 40 inches (1.02 m) long with standard 20 inch (508 mm) barrel. Stoner experimented with titanium barrels and receivers for even greater weight savings, but failed to achieve reliable operation at the time.

One distinctive ergonomic feature is a plastic or metal stock directly behind the action, which contains a recoil spring that serves the dual function of operating spring and recoil buffer. The straight-back stock and spring act to reduce muzzle rise, especially during automatic fire. As a result, most users find the M16 type rifle easy to use. Because recoil does not significantly shift the point of aim, user fatigue is reduced. This reduction in recoil coincided well with the entry of women into the military.

Another distinctive ergonomic feature is that the main sight is on the top of a carry handle on top of the receiver. This means that the user need not turn the head sideways to sight the rifle. The carry handle is also a popular feature. Newer models have a "flattop" upper receiver to which the user can attach either a conventional carry handle/sighting system or numerous optical devices such as night vision scopes.

The action is gas-operated, cocked by gases from a small hole in the barrel. The M16 design has a uniquely simple "direct drive" gas system, which also saves weight. Hot gases from the barrel vent directly into the receiver to push the bolt carrier rearward, eliminating the need for a traditional operating rod and spring assembly. While this reduces the number of moving parts and results in a simpler design, authorities differ about whether the design is more reliable than earlier service rifles.

The magazine release is on the right side of the rifle but ambidextrous mag releases are available for left-handed users. Current military magazines have 30 rounds, as opposed to the 20 round magazines issued in Vietnam. (30 round magazines were not developed and issued until late in the war.) Magazines are sometimes taped in upside-down pairs to speed reloading. Aftermarket double magazine clips are available. This practice is discouraged by military authorities because it is said to increase the chance that the top of a magazine will be damaged or pick up dirt. Nevertheless, all it takes is a quick look at recent pictures from Iraq (2004), to see that Special Forces and mainstream military forces are quick to make use of double magazine clips, as well as high-capacity magazines.

The bullet is small in caliber, 0.224 in (contrary to the 5.56 mm designation, the actual diameter is roughly 5.7 mm). The bullet often fragments when it strikes flesh. When fired from less than 100 meters, the bullet will penetrate 100 mm (4 in) into body tissue, before rotating 90 to 180 degrees. The force of bullet being pushed through dense tissue will then cause it to break nearly in half at the cannelure, which is a groove allowing the bullet casing to be sealed to the copper jacket. The rear section of the 5.56 mm bullet will then splinter into numerous tiny pieces, causing severe damage to surrounding tissue. The combination of high velocity and a fragile small bullet is more likely to cause incapacitating injuries than death by hydrostatic shock. The relatively small bullet drifts more than heavier bullets at long ranges, but users can be trained to compensate to a degree. For this reason the M16 and variants are well suited for urban and jungle warfare, unlike previous 7.62 mm infantry small arms, which cannot be fired successfully at close ranges as rapidly or with as much volume of fire.

The U.S. currently does not issue fully automatic weapons to ordinary riflemen as automatic fire is viewed as less effective as semi-automatic fire from a light weapon such as this. In any case the barrel of the M16 is too light to support sustained automatic fire and would overheat. Doctrinally, automatic fire is reserved for heavier machineguns that are designed to manage the recoil and deliver accurate fire even on fully automatic. Fully automatic fire would also expend ammunition faster and require soldiers to carry more to compensate. The fastest select-fire setting of the U.S. M16A2 rifle engages a three-part automatic sear that fires "optimal" three-round bursts for each pull of the trigger. The U.S. Army uses this feature to enhance the hit probability of troopers under combat conditions.

Variants

The original military-version XM16E1 was different in appearance from the pre-production AR-15 adding the forward assist. The M16A1, replacing the XM16E1 featured an improved "bird-cage" flash hider (replacing the old three-pronged flash hider, which was easier for foreign material to get into, and caught on twigs and leaves and the like.) Soon after its adoption, barrels with chromed chambers and later fully chromed bores were introduced for the M16A1 to down on malfunctions due to fouling and corrosion.

Modifications to the M16A2 were more extensive. In addition to the new rifling, the barrel itself was made considerably stronger at the "open end" in order to resist bending in the field. A new adjustable dual-aperture rear sight corrects for both windage and elevation for better ranged shots, possible with the new SS-109 rounds. The flash hider was again modified, this time to be closed on the bottom so it would not kick up dirt or snow when being fired prone. The front grip was also modified from the original triangular shape to a round one, which better fit smaller hands. The faster twist reduced muzzle velocity from 3200 ft/s (975 m/s) in the earlier models, to about 2900 ft/s (884 m/s) in the A2.

The action was also modified to fire either semi-automatic, or in three round bursts, as it was found troops would often simply hold down the trigger and "spray" when under fire. The Army performed years of experiments to discover and verify that three-shot groups were optimum, originally in order to develop a flechette rifle.

In Vietnam, some soldiers were issued a carbine version of the M16 called the XM177. The XM177 had a shorter barrel (~260 mm) and a telescoping stock, which made it substantially more compact. It also possessed a combination flash hider/sound moderator to reduce problems with muzzle flash and loud report. The USAF's XM177 and he US Army's XM177E1 variants differed over the later's inclusion of a forward assist. The final XM177E2 had a 290 mm barrel with a longer flash/sound suppressor. The lengthening of the barrel was to support the attachment of Colt's own XM148 40mm grenade launcher. These versions were also known as the Colt Commando model commonly, but incorrectly, referenced as the CAR-15. The variants were issued in limited numbers to special forces, helicopter crews, Air Force pilots, officers, radio operators, artillerymen, and troops other than front line riflemen.

The XM177E2 led to the M733, essentially the same gun with an M16A2 receiver and internal improvements and a flash hider/compensator to reduce perceived recoil. The M4 Carbine was developed from these designs in the early 1990s, with a 14.5 inch (368 mm) barrel and a "flat top" railed receiver. Officially adopted as a replacement for the M3 "Grease gun" (and the Beretta M9 and M16A2 for select troops) in 1994, it was used with great success in the Balkans, the 2000s War on Terrorism, and in Iraq.

Some confusion continues to exist, in spite of the evidence provided by US government manuals and other documentation, concerning the M16A3 and M16A4. The M16A3 was adopted in small numbers around the time of the introduction of the M16A2, primary by the US Navy for use by the SEALs. The M16A3 is identical to the A2, but instead features a Safe-Semi-Auto (S-1-F) trigger group like that of the A1. The A4, now standard issue for frontline US Army and USMC units, features a flat top, M1913 Pictinny rail equipped upper receiver. Descriptions of the M16A3 that claim that it is also a flat top are incorrect. This misnomer most likely stems from the usage of the A2 and A3 designations by civilian manufacturers to differentiate between A2 style fixed carry handles and flat top receivers.

Production and usage

The M16 is the most commonly manufactured 5.56 x 45 mm weapon in the world. Currently, the M16/M4 system is in use by 15 NATO countries and more than 80 countries world wide. Together, the U.S., Canada (as the C7), Singapore, and China have produced more than 8,000,000 units with approximately 90% still in operation [1] (http://www.colt.com/mil/customers.asp).

See also

External links

de:M16 (Gewehr) fr:M16 (fusil) he:M16 ja:M16 nl:M16 pl:Karabin M16 sl:M16 sv:M16 fi:M16 zh:M16突击步枪

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