AR-18
Encyclopedia
The AR-18 is a gas operated, selective fire
assault rifle
chambered for 5.56x45mm
ammunition
. The AR-18 was designed at ArmaLite
in California by Arthur Miller, George Sullivan, and Charles Dorchester in 1963 as an improved alternative to the AR-15
design, which had just been selected by the U.S. military as the M16
. While the AR-18 was never adopted as the standard service rifle of any nation, it is said to have influenced many later weapons such as the British SA80
, the Singaporean SAR-80
and SR-88
, the Austrian Steyr AUG, and the Heckler and Koch G36. It gained some notoriety through its use by the Provisional IRA, who allegedly christened it the "Widowmaker."
rifle in 1957, the U.S. Army's
Continental Army Command (CONARC) began an investigation of Small Caliber High Velocity (SCHV) rifles as an off-shoot of the military's existing research program, Project SALVO
. ArmaLite and Winchester Arms were solicited by CONARC to provide prototype automatic rifles chambered for high velocity centerfire .22 rounds. ArmaLite's AR-15
was a scaled down version of the 7.62mm AR-10
, which had appeared too late to be a serious contender against the M14. Its competitor from Winchester was a remake of a 'Carbine' Williams
prototype carbine design, which had been completed too late to prevent the adoption of the M1 carbine
.
. Fairchild also spun off ArmaLite as an independent company, allowing the new owners to buy all of the company's designs except for the AR-10 and AR-15. When the U.S. military ultimately selected the AR-15 as the M16, ArmaLite could no longer profit from its adoption.
's final design for ArmaLite. The AR-16 and its predecessor, the AR-12 were designed by Stoner in response to demands by the military forces of smaller, less developed nations for a less expensive, yet state-of-the-art selective-fire military rifle that unlike the AR-10 and AR-15, could be produced inexpensively of heavy-gauge sheet metal using automatic screw machines, lathes, and presses. The AR-12 originally featured a direct-impingement (DI) gas operation system, but this was changed to a more conventional short-stroke gas piston in the AR-16 after ArmaLite sold the production rights to the DI system to Colt Firearms. The AR-16 had a short, 15-inch barrel, hinged wooden butt, and weighed 8.75 pounds empty; only three examples were built. Eugene Stoner left ArmaLite in 1961, shortly before Fairchild divested itself of ownership.
The AR-18's action was powered by a short-stroke gas piston above the barrel. The gas piston was of 3-piece design to facilitate disassembly, with a hollow forward section with 4 radial gas vent holes fitting around a stainless steel gas block projecting rearwards from the foresight housing. The gas was vented from the barrel and travelled via a vent through the foresight housing into the hollow front section of the piston, which caused it to move rearwards a short distance. The rear end of the piston emerged through the barrel extension to contact the forward face of the bolt carrier, causing it in turn to move rearwards. The bolt itself was of similar configuration to the AR-15 with 7 radial locking lugs engaging corresponding recesses in the barrel extension, and the extractor in place of the 8th lug. The bolt was moved into and out of the locked position via a cam pin that engaged a helical slot in the bolt carrier, which rode on two metal guide rods (each with its own return spring) instead of contacting the receiver walls, providing additional clearance for foreign matter entering the receiver. Unlike the AR-15, the cocking handle fitted directly into a recess in the bolt carrier and reciprocated with it during firing, allowing the firer to force the breech closed or open if necessary. The cocking handle slot had a spring-loaded cover that could be closed by the user to prevent debris entering the receiver, and it would open automatically as the bolt carrier moved rearwards after the first shot. The recoil springs were housed within the receiver, differing from the AR-15 which housed its more elaborate buffer mechanism in the buttstock. The AR-18's compact design enabled the use of a side-folding stock with a hinging mechanism (that later proved to be less than adequately rigid).
The sights were of similar design and sight picture to those of the AR-15 - a 2-position flip aperture rear sight and post foresight - but the rear sight was made of stampings. A notable change is the use of a more conventional lower sight line closer to the axis of the bore, in contrast to the elevated sights of the AR-15. A dovetail was spot welded to the receiver in front of the rear sight for a proprietary ArmaLite quick-detachable scope mount.
Overall, the design is simple and effective with some clever touches; for example the bolt guide rod assembly guides the bolt in the receiver, retains the recoil springs and the rear end of the top handguard, as well as serving as the latch holding the upper and lower receivers together in the closed position. Disassembly is somewhat similar to the AR-15, with the working parts accessed by the rifle pivoting open on a cross-pin immediately forward of the magazine well.
, of Japan
, and the rifle was produced there from 1970 until 1974, when new controls on export of military arms by the Japanese government forced the company to cease all small arms production. From 1975 until 1983, the Sterling Armaments Company
of Dagenham, Essex, in the United Kingdom produced the AR-18/AR-180.
Unlike the AR-15/M16, the AR-18 did not see substantial sales success, and was not not officially adopted by any nation as a standard service rifle. The reasons for this are unclear, but may have had something to do with the existing sales popularity of the AR-15/M-16, as well as the need for additional field testing and evaluation of the Costa Mesa-produced rifles, which were still in the advanced prototype stage. The AR-18 was purchased for evaluation trials by various armed forces, including the United States (1964) and the United Kingdom (1966). These suffered various malfunctions during evaluation trials by various nations. During the US trials at Aberdeen Proving Grounds in 1964, the AR-18's functioning was found to vary from lot to lot of ammunition. The evaluating board concluded that while the basic design of the AR-18 was sound, it required additional minor revisions and changes to improve safety and reliability before it could be considered for adoption as a service rifle. The British Ministry of Defence (MOD) tested the AR-18 in March 1966, and found the design unsatisfactory in performance during mud and sand trials. ArmaLite made several minor production modifications to the design commencing in 1965, and the U.S. Army was directed to re-evaluate the AR-18 at the end of 1969. Testing was conducted at Aberdeen Proving Grounds, conducted by arsenal employees and the Infantry Board at Fort Benning, Georgia. However, American procurement officials were not interested in acquiring yet another 5.56 mm service rifle. Instead, the AR-180 was sold on the civilian market, while the AR-18 sold in small quantities to police and law enforcement organizations, as well as armies and security forces of nations such as Botswana
, Haiti
, and Swaziland
. Still others found their way into the hands of terrorist or paramilitary groups, such as the Provisional IRA in Northern Ireland
. In 1968, dissatisfied with efforts to market the AR-18, Arthur Miller left ArmaLite.
The AR-180 was capable of semi-automatic fire only and was externally identical in appearance to the AR-18 with one exception; the selector had only 2 positions, omitting the third "AUTO" position found on the AR-18.
Sterling manufactured a small number of sporter variants called the AR-180 SCS, of which only 385 were reputed to have been made. It had a large single-piece wooden thumbhole stock that replaced the butt, pistol grip and handguard of conventional versions. The metal parts differ in the lack of the ejection port cover, and a PH prefix to the serial number and adapted safety and magazine release controls.
Sterling also manufactured small numbers of a short version, the AR-18S. This version used the same basic mechanism and folding butt, but had a 257-mm barrel and a length of 765mm (30 in) with the butt extended. The shortened barrel was fitted with a cone-shaped flash suppressor to address the additional muzzle flash resulting from the short barrel. Some examples had an additional pistol grip fitted to the underside of the handguard.
A 2.75 X 20 mm telescopic sight was available but few were sold. It was marked "ArmaLite", and had a quick-detachable, see-through mount that attached to an integral dovetail spot-welded to the top of the receiver.
Also to note a bullpup conversion of the AR-18 and the Stoner 63
was made by Enfield, the rival company of Sterling Armaments Ltd when developing the SA80
.
is planned for production.
Selective fire
A selective fire firearm has at least one semi–automatic and one automatic mode, which is activated by means of a selector which varies depending on the weapon's design. Some selective fire weapons utilize burst fire mechanisms to limit the maximum or total number of shots fired automatically in...
assault rifle
Assault rifle
An assault rifle is a selective fire rifle that uses an intermediate cartridge and a detachable magazine. Assault rifles are the standard infantry weapons in most modern armies...
chambered for 5.56x45mm
5.56x45mm NATO
5.56×45mm NATO is a rifle cartridge developed in the United States and originally chambered in the M16 rifle. Under STANAG 4172, it is a standard cartridge for NATO forces as well as many non-NATO countries. It is derived from, but not identical to, the .223 Remington cartridge...
ammunition
Ammunition
Ammunition is a generic term derived from the French language la munition which embraced all material used for war , but which in time came to refer specifically to gunpowder and artillery. The collective term for all types of ammunition is munitions...
. The AR-18 was designed at ArmaLite
ArmaLite
ArmaLite is the name of a small arms engineering facility founded in the early 1950s, and once associated with the Fairchild Engine and Airplane Corporation. ArmaLite was formally incorporated as a subdivision of Fairchild on October 1, 1954...
in California by Arthur Miller, George Sullivan, and Charles Dorchester in 1963 as an improved alternative to the AR-15
AR-15
The AR-15 is a lightweight, 5.56 mm, air-cooled, gas-operated, magazine-fed semi-automatic rifle, with a rotating-lock bolt, actuated by direct impingement gas operation. It is manufactured with the extensive use of aluminum alloys and synthetic materials....
design, which had just been selected by the U.S. military as the M16
M16 rifle
The M16 is the United States military designation for the AR-15 rifle adapted for both semi-automatic and full-automatic fire. Colt purchased the rights to the AR-15 from ArmaLite, and currently uses that designation only for semi-automatic versions of the rifle. The M16 fires the 5.56×45mm NATO...
. While the AR-18 was never adopted as the standard service rifle of any nation, it is said to have influenced many later weapons such as the British SA80
SA80
The SA80 is a British family of 5.56mm small arms. It is a selective fire, gas-operated assault rifle. SA80 prototypes were trialled in 1976 and production was completed in 1994....
, the Singaporean SAR-80
SAR-80
The Singapore Assault Rifle 80 is an indigenously built, conventional assault rifle from Singapore.-History and development:In the late 1960s, the Singapore Armed Forces adopted the AR-15 as their main service rifle...
and SR-88
SR-88
The SR-88 is an assault rifle designed and manufactured in Singapore by Chartered Industries of Singapore .-Development:...
, the Austrian Steyr AUG, and the Heckler and Koch G36. It gained some notoriety through its use by the Provisional IRA, who allegedly christened it the "Widowmaker."
Background
Soon after the adoption of the 7.62x51mm NATO M14M14 rifle
The M14 rifle, formally the United States Rifle, 7.62 mm, M14, is an American selective fire automatic rifle firing 7.62x51mm NATO ammunition. It was the standard issue U.S. rifle from 1959 to 1970. The M14 was used for U.S...
rifle in 1957, the U.S. Army's
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...
Continental Army Command (CONARC) began an investigation of Small Caliber High Velocity (SCHV) rifles as an off-shoot of the military's existing research program, Project SALVO
Special Purpose Individual Weapon
The Special Purpose Individual Weapon was a long-running United States Army program to develop, in part, a workable flechette-based "rifle", though other concepts were also involved...
. ArmaLite and Winchester Arms were solicited by CONARC to provide prototype automatic rifles chambered for high velocity centerfire .22 rounds. ArmaLite's AR-15
AR-15
The AR-15 is a lightweight, 5.56 mm, air-cooled, gas-operated, magazine-fed semi-automatic rifle, with a rotating-lock bolt, actuated by direct impingement gas operation. It is manufactured with the extensive use of aluminum alloys and synthetic materials....
was a scaled down version of the 7.62mm AR-10
AR-10
The AR-10 is an American 7.62 mm battle rifle developed by Eugene Stoner in the late 1950s at ArmaLite, then a division of the Fairchild Aircraft Corporation...
, which had appeared too late to be a serious contender against the M14. Its competitor from Winchester was a remake of a 'Carbine' Williams
David Marshall (Carbine) Williams
David Marshall Williams , also known as Carbine Williams was an American designer of the short-stroke piston used in the M1 Carbine as well as the floating chamber operating system for firearms.-Early life:...
prototype carbine design, which had been completed too late to prevent the adoption of the M1 carbine
M1 Carbine
The M1 carbine is a lightweight, easy to use semi-automatic carbine that became a standard firearm for the U.S. military during World War II, the Korean War and the Vietnam War, and was produced in several variants. It was widely used by U.S...
.
M16
During the protracted U.S. military trials of the AR-15, ArmaLite's corporate owners Fairchild essentially gave up on the design, and sold the AR-15 production rights to ColtColt's Manufacturing Company
Colt's Manufacturing Company is a United States firearms manufacturer, whose first predecessor corporation was founded in 1836 by Sam Colt. Colt is best known for the engineering, production, and marketing of firearms over the later half of the 19th and the 20th century...
. Fairchild also spun off ArmaLite as an independent company, allowing the new owners to buy all of the company's designs except for the AR-10 and AR-15. When the U.S. military ultimately selected the AR-15 as the M16, ArmaLite could no longer profit from its adoption.
AR-16
The AR-16 appeared in the later 1950s. The AR-16, a 7.62mm NATO selective-fire rifle, was Eugene StonerEugene Stoner
Eugene Morrison Stoner is the man most associated with the design of the AR-15, which was adopted by the US military as the M16...
's final design for ArmaLite. The AR-16 and its predecessor, the AR-12 were designed by Stoner in response to demands by the military forces of smaller, less developed nations for a less expensive, yet state-of-the-art selective-fire military rifle that unlike the AR-10 and AR-15, could be produced inexpensively of heavy-gauge sheet metal using automatic screw machines, lathes, and presses. The AR-12 originally featured a direct-impingement (DI) gas operation system, but this was changed to a more conventional short-stroke gas piston in the AR-16 after ArmaLite sold the production rights to the DI system to Colt Firearms. The AR-16 had a short, 15-inch barrel, hinged wooden butt, and weighed 8.75 pounds empty; only three examples were built. Eugene Stoner left ArmaLite in 1961, shortly before Fairchild divested itself of ownership.
AR-18
The U.S. military's later adoption of the AR-15 gave legitimacy to its 5.56mm cartridge, and ArmaLite sought to develop a competing design chambered in 5.56mm. With Stoner gone, it was decided to scale down the AR-16, and ArmaLite's new chief designer, Arthur Miller, embarked on the project. The resulting 5.56mm design appeared in 1963 and was named the AR-18. Miller later received for the rifle in 1969.Construction and design
Overall, the new AR-18 rifle was much more conventional than previous ArmaLite designs. As mentioned earlier, the AR-18 was constructed from stamped steel upper and lower receivers and other components. Compared to the smooth lines of the AR-15, the AR-18 faced criticism over its stamped and welded construction, which had demonstrably greater tolerances in parts fit. At the time, sheet metal stampings and welded components were a revelation when used in military rifles, traditionally constructed of machined forgings. However, the rifle proved to be both reliable and very accurate at all ranges up to 460 meters (503 yards). Its simple construction promised significantly reduced production costs, and allowed it to be produced locally on less advanced machinery, reducing dependence on foreign manufacturers. Moreover, the gas piston operation of the AR-18 proved much more resistant to carbon fouling than that of the earlier AR-10 and AR-15 rifles.The AR-18's action was powered by a short-stroke gas piston above the barrel. The gas piston was of 3-piece design to facilitate disassembly, with a hollow forward section with 4 radial gas vent holes fitting around a stainless steel gas block projecting rearwards from the foresight housing. The gas was vented from the barrel and travelled via a vent through the foresight housing into the hollow front section of the piston, which caused it to move rearwards a short distance. The rear end of the piston emerged through the barrel extension to contact the forward face of the bolt carrier, causing it in turn to move rearwards. The bolt itself was of similar configuration to the AR-15 with 7 radial locking lugs engaging corresponding recesses in the barrel extension, and the extractor in place of the 8th lug. The bolt was moved into and out of the locked position via a cam pin that engaged a helical slot in the bolt carrier, which rode on two metal guide rods (each with its own return spring) instead of contacting the receiver walls, providing additional clearance for foreign matter entering the receiver. Unlike the AR-15, the cocking handle fitted directly into a recess in the bolt carrier and reciprocated with it during firing, allowing the firer to force the breech closed or open if necessary. The cocking handle slot had a spring-loaded cover that could be closed by the user to prevent debris entering the receiver, and it would open automatically as the bolt carrier moved rearwards after the first shot. The recoil springs were housed within the receiver, differing from the AR-15 which housed its more elaborate buffer mechanism in the buttstock. The AR-18's compact design enabled the use of a side-folding stock with a hinging mechanism (that later proved to be less than adequately rigid).
The sights were of similar design and sight picture to those of the AR-15 - a 2-position flip aperture rear sight and post foresight - but the rear sight was made of stampings. A notable change is the use of a more conventional lower sight line closer to the axis of the bore, in contrast to the elevated sights of the AR-15. A dovetail was spot welded to the receiver in front of the rear sight for a proprietary ArmaLite quick-detachable scope mount.
Overall, the design is simple and effective with some clever touches; for example the bolt guide rod assembly guides the bolt in the receiver, retains the recoil springs and the rear end of the top handguard, as well as serving as the latch holding the upper and lower receivers together in the closed position. Disassembly is somewhat similar to the AR-15, with the working parts accessed by the rifle pivoting open on a cross-pin immediately forward of the magazine well.
Production and service use
The AR-18 was put into limited production at ArmaLite's machine shop and offices in Costa Mesa, California. A semi-automatic version of the AR-18 known as the AR-180 was later produced for the civilian market between 1969 and 1972. ArmaLite was never equipped to build small arms on a production basis, and the Costa Mesa AR-18 and AR-180 rifles frequently show evidence of hand-fitting. A production license was granted to Nederlandsche Wapen-en Munitiefabriek (NWM) of Den Bosch, the Netherlands, but it is doubtful that any AR-18 rifles were actually produced there. A license to produce the AR-18/180 was then sold to Howa Machinery Co.Howa
) is a Japanese machinery manufacturer. The company is known internationally for their production of military and civilian firearms. However, they also manufacture civilian products such as industrial tools, construction vehicles and windows and doors....
, of Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, and the rifle was produced there from 1970 until 1974, when new controls on export of military arms by the Japanese government forced the company to cease all small arms production. From 1975 until 1983, the Sterling Armaments Company
Sterling Armaments Company
Sterling Armaments Company was an arms manufacturer based in Dagenham, famous for manufacturing the L2A3 , AR18 and SAR-87 assault rifles and parts of Jaguar cars. The company went bankrupt in 1988....
of Dagenham, Essex, in the United Kingdom produced the AR-18/AR-180.
Unlike the AR-15/M16, the AR-18 did not see substantial sales success, and was not not officially adopted by any nation as a standard service rifle. The reasons for this are unclear, but may have had something to do with the existing sales popularity of the AR-15/M-16, as well as the need for additional field testing and evaluation of the Costa Mesa-produced rifles, which were still in the advanced prototype stage. The AR-18 was purchased for evaluation trials by various armed forces, including the United States (1964) and the United Kingdom (1966). These suffered various malfunctions during evaluation trials by various nations. During the US trials at Aberdeen Proving Grounds in 1964, the AR-18's functioning was found to vary from lot to lot of ammunition. The evaluating board concluded that while the basic design of the AR-18 was sound, it required additional minor revisions and changes to improve safety and reliability before it could be considered for adoption as a service rifle. The British Ministry of Defence (MOD) tested the AR-18 in March 1966, and found the design unsatisfactory in performance during mud and sand trials. ArmaLite made several minor production modifications to the design commencing in 1965, and the U.S. Army was directed to re-evaluate the AR-18 at the end of 1969. Testing was conducted at Aberdeen Proving Grounds, conducted by arsenal employees and the Infantry Board at Fort Benning, Georgia. However, American procurement officials were not interested in acquiring yet another 5.56 mm service rifle. Instead, the AR-180 was sold on the civilian market, while the AR-18 sold in small quantities to police and law enforcement organizations, as well as armies and security forces of nations such as Botswana
Botswana Defence Force
The Botswana Defence Force is the military of Botswana. It was formed in 1977 and has approximately 9,000 members. The commander is Lieutenant General Tebogo Masire. The commander in chief is the President of Botswana...
, Haiti
Haiti
Haiti , officially the Republic of Haiti , is a Caribbean country. It occupies the western, smaller portion of the island of Hispaniola, in the Greater Antillean archipelago, which it shares with the Dominican Republic. Ayiti was the indigenous Taíno or Amerindian name for the island...
, and Swaziland
Swaziland
Swaziland, officially the Kingdom of Swaziland , and sometimes called Ngwane or Swatini, is a landlocked country in Southern Africa, bordered to the north, south and west by South Africa, and to the east by Mozambique...
. Still others found their way into the hands of terrorist or paramilitary groups, such as the Provisional IRA in Northern Ireland
Northern Ireland
Northern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...
. In 1968, dissatisfied with efforts to market the AR-18, Arthur Miller left ArmaLite.
Variants
The standard AR-18 versions manufactured by ArmaLite, Howa and Sterling differ only in minor details. Rifles were normally equipped with sling, cleaning kit (bore/brush), and a knife-type bayonet with scabbard. An optional bipod with case was available.The AR-180 was capable of semi-automatic fire only and was externally identical in appearance to the AR-18 with one exception; the selector had only 2 positions, omitting the third "AUTO" position found on the AR-18.
Sterling manufactured a small number of sporter variants called the AR-180 SCS, of which only 385 were reputed to have been made. It had a large single-piece wooden thumbhole stock that replaced the butt, pistol grip and handguard of conventional versions. The metal parts differ in the lack of the ejection port cover, and a PH prefix to the serial number and adapted safety and magazine release controls.
Sterling also manufactured small numbers of a short version, the AR-18S. This version used the same basic mechanism and folding butt, but had a 257-mm barrel and a length of 765mm (30 in) with the butt extended. The shortened barrel was fitted with a cone-shaped flash suppressor to address the additional muzzle flash resulting from the short barrel. Some examples had an additional pistol grip fitted to the underside of the handguard.
A 2.75 X 20 mm telescopic sight was available but few were sold. It was marked "ArmaLite", and had a quick-detachable, see-through mount that attached to an integral dovetail spot-welded to the top of the receiver.
Also to note a bullpup conversion of the AR-18 and the Stoner 63
Stoner 63
The Stoner 63, also known as the XM22/E1, is an American modular weapons system designed by Eugene Stoner in the early 1960s. It was produced by Cadillac Gage and used in very limited numbers in Vietnam by members of the United States Navy SEALs and several law enforcement...
was made by Enfield, the rival company of Sterling Armaments Ltd when developing the SA80
SA80
The SA80 is a British family of 5.56mm small arms. It is a selective fire, gas-operated assault rifle. SA80 prototypes were trialled in 1976 and production was completed in 1994....
.
Recent developments
The ArmaLite brand was purchased in 1996 by Eagle Arms, a small U.S. arms manufacturer, who adopted the ArmaLite brand for their company. An updated model of the AR-180 was introduced in 2001 as the AR-180B, with a molded polymer lower receiver replacing the stamped steel original. The new lower receiver is combined with the buttstock, which is fixed on the AR-180B, instead of the side-folding butt on the original AR-18 and AR-180. Other AR-180B changes include the use of standard AR-15 trigger group and rear sight parts, and the deletion of the original AR-18/180 spring-loaded dust cover for the cocking handle slot. The AR-15 magazine release is also used, in contrast to the original AR-18 which had a different magazine release and corresponding slot in the body of the magazine, meaning AR-15 magazines needed a new slot cut to fit properly in the AR-18. As a result the AR-180B uses standard AR-15/M16 magazines. An AR-180B version with a Picatinny railPicatinny rail
The Picatinny rail or MIL-STD-1913 rail or STANAG 2324 rail or a "Tactical Rail" is a bracket used on some firearms in order to provide a standardized mounting platform. A similar system is the Weaver rail mount.-Description:...
is planned for production.