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- M16 is also the Eagle Nebula in astronomy.
The M16 is an assault rifle which fires NATO 5.56 mm ammunition. This has been the standard infantry weapon of the US Army since 1964. It is manufactured by Colt and Fabrique Nationale; with variants produced by Heckler und Koch, Knight's Armament, Bushmaster, Diemco (as the C7 in Canadian service), Panther Arms, and many other arms companies. The M16A2 (shown below) replaced the M16A1 before being replaced by the XM-8 and M4 assault rifles in 2003-2006.
History
In the 1950s various military forces were studying the impact of the StG44, the world's first true assault rifle. The basic concept of this weapon was to reduce the power of the rounds in order to control recoil, and making up for the lack of single-bullet power by allowing the gun to fire in fully automatic. This dramatically increased the overall firepower of a squad equipped with such weapons, a late war German 8-man unit with StG 44's and a single MG 42 had roughly the same firepower as three or four US or British units.
The British immediately turned to the design of their own assault rifle, in order to replace their hopelessly outdated WWI-vintage bolt-action SMLEs. They eventually selected a .280" (7mm) round with somewhat higher power than the StG44's short rounds, 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 Garands.
The Garand was by no means a perfect weapon, however, and several experiments were carried out to improve it. A common one was to replace the hard-to-use "stripper" clips with a box magazine holding 20 rounds. This led to a number of test rifles in the early 1950s. When NATO standardization was first being considered up the US demanded that a powerful round similar to the Garand's be used. The British noted the problems with recoil, but the US Army stuck to their demands, and eventually the 7.62 NATO round was standardized. In the end the British fears proved right, and neither the resulting US M14 rifle nor the British FN FAL could be fired in automatic. The US thus spent a considerable amount of money replacing one semi-automatic design with another, while the Red Army went on to introduce the fully automatic AK47 instead.
Following this selection, Eugene Stoner of Armalite Systems designed the AR-10, a new 7.62 NATO assault rifle that combined features from a number of earlier designs into one of the best designs of its era. It took its basic layout from the famed [[Stg 44], including the way the weapon "folded open" for cleaning the firing mechanism. It combined this with a light operating mechanism adapted from a new Swedish design. He then added his own touch, now instantly recognizable, by making the buttstock flush with the top of the weapon in order to control recoil. This would normally make the sights "to low" for easy aiming, a problem he solved by mounting them on top of a carrying handle. The result was a fairly compact weapon with excellent carrying qualities, fast aim, and low recoil. It was built in small numbers in the Netherlands, but it saw few sales and no official adoption.
CONARC and Project SALVO
While the 7.62 debate was being carried out, the the United States Army Continental Army Command (CONARC) had quietly been carrying out research studies into the issue under Project SALVO. Running between 1953 and 1957, SALVO, run by the Army's operational research division, found exactly what the British had a few years earlier, and the Germans a decade ago; volume of fire was considerably more important than aim, shots were rarely taken at over 300 yards, and hits rarely above 100.
SAVLO studied a number of solutions to these problems, including a duplex cartridge using two projectiles stacked one above the other, and an Earle Harvey designed a trajectory altering device to cause a bullet to take a slightly different path than the previously fired bullet. In the end, however, their conclusion was to simply use a .22" caliber round, even smaller than the British designs, which would allow the troops to carry much more ammunition and fire it fully automatic. However their research was being carried out during the US/British debates, and kept secret in case the British used it in their own defence.
After SALVO ended CONARC offered contract tenders for such a design. Their demands were for a rifle that was under 6 pounds loaded with 20 rounds of ammuntion, fully or semi-automatic "select fire" operation, and able to penetrate both sides of a standard Army helmet at 500 yards. At first the contracts were offered only to Winchester Arms and the Springfield Armory, but Willard Wyman had seen the AR-10 and asked Armalite to enter as well.
As expected, Winchester and Springfield Armory both turned in designs based on their existing rifles, firing a new .224" round. The Winchester was a straight adaptation of the M1 Carbine, while the Springfield was an equally uninspiring adaptation of the M14. The Springfield design was never even submitted, after people opposed to the "light round" concept in their beauracracy had the project killed. Springfield closed in 1968, largely as a result of this debacle.
Less expected was Armalite's submission, the AR-15, which was unlike anything seen before. To meet the 500 meter standard, Stoner had Remington Arms] increase the capacity of their .222 Remington cartridge to fire a 55-grain bullet at 3300 feet per second. The new round, known as the .223 Remington, was just powerful enough to meet the requirements. However it was also not powerful enough that he was able to produce a dramatically lighter design, including plastics for the stock and grips in place of wood or aluminum, a "folded" design with the operating spring in the stock, and extensive use of stamped parts for ease of manufacture. The AR-15 was only 2.89 kilograms empty, about 3.5 loaded.
The AR-15 was lighter, smaller, more powerful and less expensive than the Winchester design. Its only major problem was that it wasn't fully developed before Army testing began nine months later on March 31st, 1958. But later tests showed some problems. Rainwater in one AR-15 barrel caused it to burst when fired. Stoner redesigned and strengthened the barrel, but Ordnance engineers said the problem would remain due to the .22-caliber size of the barrel. Several rifles sent to the Army Army Arctic Test Board also failed, but when Stoner flew to Alaska to investigate, he found they had been improperly reassembled after cleaning.
The Army then began to stonewall Stoner over the suitability of the AR-15. They suggested that if the weapon were re-chambered for their new .258 caliber round then it would be acceptable. Meanwhile General Maxwell Taylor was dead-set against the design, and pressed for continued production of the M14.
At this point Farichild had spent $1.45 million in development expense, and there was no end in sight. Fairchild sold its rights to 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 Curtiss LeMay in June 1960. He immediately ordered 8500 for defense at Strategic Air Command airbases. Colt 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.
The Army was innundated with reports of poor battlefield performance of the M14, along with the latest ARPA report on the AR-15, suggesting it would give US troops a real edge over their AK47-equipped Soviet counterparts. Secretary of Defense Robert McNamara now had two conflicting views: the ARPA report favoring the AR-15 and the Army's (or Maxwell Taylor'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 and 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 1963. 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 theirs as the United States Rifle, Caliber 5.56mm, M16. The Army continued to dither, however.
When the M14 reached Viet Nam with US troops in 1965 it's flaws were instantly recognized. It was far too long to operate effectively in a jungle enviornment, and the heavy ammunition meant only small quantities were carried on patrol. The fully automatic fire quickly demonstrated itself as useless, and the rifles were eventually delivered locked in semi-automatic. Troops took to scrounging any weapon they could find, the Tommy gun became particularily well-used.
Nevertheless the Army continued to argue over the M16, and demanded the addition of a "forward assist" device to close the bolt in case of a misfeed. Colt, the Air Force, the Marine Corps and Eugene Stoner all agreed this device 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 as the M16A1.
Colt had oversold the M16's reliability during testing, to the point where they suggested the chrome lining of the barrel and receiver meant it never had to be cleaned. While this may have been true with the original IRM power the rounds were originally made with, the Army used a ball powder that was considerably "dirtier". The firing mechanism, adapted from the Ljungman AG42B, used an open tube from the front of the barrel that vented gas directly onto the front of the bolt. In normal designs the gas pressed on a rod which operated the bolt, 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 were not supplied with cleaning kits. 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. Luckily cooler heads prevailed. Cleaning kits were quickly produced, and a comic book was circulated among the troops to demonstrate proper maintenance. The 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 adopt the rifle whenever one could be found. After its rocky start, the M16 has since proven itself to be one of the most reliable combat rifles ever produced.
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, cut down from their wartime 7.62mm "full calibre" design. The debate ended for good when they introduced their own small round, one even smaller than the M16 at only 5.45mm. Apparently SALVO had the right idea all along.
NATO standardization
In March 1970 the Army 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 7.62mm NATO round because their .280 caliber round wasn't effective enough nearly twenty years earlier.
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 introduction of body armor. The British introduced a modified 5.56 round, using a longer and thinner bullet of 4.85mm, mounted in the existing US cartridges. The round had somewhat better ballistics, and considerably better penetration. The Germans introduced a new 4.7mm caseless ammunition, 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 using both the US cartridge and a new bullet with the same 5.56mm caliber, but with a small tip of steel 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 examples.
Future Replacement?
Later in the 80's the Advanced Combat Rifle program was run to find a replacement for the M16. The Army was pressing for a 100% increase in the the ability for infantry to hit their targets.
Colt entered a modified M16A2 known as the Colt ACR, which used a system that lowered recoil by 40% to allow better repeating shots, and added a 3.5x scope. The Steyr ACR used a new flechette ammunition that was nominally called 5.56mm, with a very high 4750mps 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 OICW project for a radically improved weapon. The XM8 design uses a computer aimed 20mm grenade launcher combined with a small 5.56 rifle for short-ranges. However the program is very expensive, and it seems unlikely it will be adopted for use.
Design
The M16 is made of aluminum and plastics, except for the steel barrel and parts of the action. Early models were especially lightweight at 3.2 kg (~7.5 lbs), about 30% less than older 7.62 mm "battle rifles" of the 1950s and 1960s. It also comares very favourably with the 5kg AK47. New models weigh more (~8.5 lbs) because of the "heavy" barrel used to increase accuracy. The gun is 40 inches in length. Stoner experimented with titanium barrels and receiver 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 straigh-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 Army.
Another distinctive ergonomic feature is that the main sight is in 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 can be switched for left-handed users. Current military magazines have 30 rounds, and 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 caliber, 5.56 mm (0.223 in), and often fragments when it strikes flesh. 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.
Variants
The first revision to the M16 was minor—the replacement of the original "pronged" flash suppressor with a "birdcage" model because of complaints that the pronged version snagged on brush in Vietnam. 30-round magazines were also soon introduced.
The M16A1 added several feaures to the original AR-15, including the forward-assist lever and a hinged cover over the ejector ports to keep dirt out of the receiver. Improvements in the ammunition improved the firing rates from 700 to 900 rounds per minute.
Modifications for 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 modifed 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 XM-177 or CAR-15. The XM-177 had a shorter barrel (~26 cm) and a telescoping stock, which made it substantially more compact. Numerous problems with muzzle flash and loud report resulted in Colt modifying the design to produce the XM-177E1 and XM-177E2 toward the end of the Vietnam conflict. The final XM-177E2 had a 29 cm barrel with a long flash suppressor. This version became known as the Colt Commando model and was issued in limited numbers to special forces, helicopter crews, Air Force pilots, officers, radio operators, artillerymen, and troops other than front line riflemen.
The XM-177E2 lead 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 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.
In 2003 the U.S. Army has issued limited numbers of a improved variants, the M16A3 and M16A4, which incorporate a rail mounting system similar to the M4A1 Carbine.
Production and Usage
The M16 is the most commonly manufactured 5.56x45mm 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
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