Armalite AR-18

The AR-18 is an assault rifle chambered for 5.56 x 45 mm NATO ammunition. The AR-18 was designed by Arthur Miller, George Sullivan, and Charles Dorchester at ArmaLite in 1963 as an improved 5.56 mm caliber alternative to Armalite\'s previous AR-15 design, for which production rights had been sold to Colt. Interest in the design waned when the Colt AR-15 was selected for production by the US Army as the M16. Unlike the AR-15/M16, the AR-18 did not see substantial improvement, and was not adopted in large numbers by any military service. In the end, the commercial failure of the AR-18 was not due to any significant flaws in its basic design, but in the lack of marketing efforts by ArmaLite. In 1968, dissatisfied with the way ArmaLite had marketed the AR-18, Arthur Miller left ArmaLite.

Armalite AR-18
Class Manportable
Type Rifles
Manufacturer ArmaLite
Origin United States of America
Country Name Origin Year
United States of America 1963
Country Name Operational Year Retirement Year
Haiti View
Ireland View
Switzerland View
United States of America View
Botswana View
ManufacturerName Production From Production To Quantity
ArmaLite View
Howa View
Sterling Armaments Company View

Overall, the new AR-18 rifle is much more conventional than previous ArmaLite designs, although it uses the relatively new stamped steel construction from its predecessor, the AR-16. Despite being pioneered by the Germans during WW2 in weapons such as the MP44, and later adopted for the Soviet AKM, the use of stamped and welded sheet metal components was still uncommon in the manufacture of military rifles in the West in the early 1960s, which had, until then, largely retained the use of traditional machined forgings. 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. However, the rifle proved to be both reliable and very accurate at all ranges up to 460 metres (500 yards). Its simple construction promised significantly reduced production costs, and allowed it to be licence-produced locally on less advanced machinery, potentially reducing dependence on foreign manufacturers. Moreover, the gas piston operation of the AR-18 proved much more resistant to carbon fouling than the direct gas impingement system of the earlier AR-10 and AR-15 rifles, as it does not vent gas and carbon particles directly into the receiver.

The AR-18's action is powered by a short-stroke gas piston above the barrel. The gas piston is 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 is vented from the barrel and travelled via a vent through the foresight housing into the hollow front section of the piston, which causes it to move rearwards a short distance. The rear end of the piston emerges through the barrel extension to contact the forward face of the bolt carrier, causing it in turn to move rearwards. The bolt itself is 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 is moved into and out of the locked position via a cam pin that engaged a helical slot in the bolt carrier, which rides 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 fits directly into a recess in the bolt carrier and reciprocates with it during firing, allowing the firer to force the breech closed or open if necessary. The cocking handle slot has a spring-loaded cover that can be closed by the user to prevent debris entering the receiver, and it will open automatically as the bolt carrier moves rearwards after the first shot. The recoil springs are housed within the receiver, differing from the AR-15 which houses its more elaborate buffer mechanism in the buttstock. The AR-18's compact design enables the use of a side-folding stock with a hinging mechanism (which proved to be less than adequately rigid).

The sights are 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 is 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 is 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.

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., 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 never officially adopted by any country as their 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.

Weight - 3.17 kg (empty)
Length - 73.6 cm (stock folded)/ 94cm
Barrellength - 46.4cm
Cartridge - 5.56x45mm NATO
Action - Gas operated, rotating bolt
Rateoffire - 800 rounds/min
Muzzlevelocity - 1000 m/s (3281 fps)
Feedsystem - 20, 30, or 40-round box magazine
Sights - Iron or removable 3x scope

End notes