Armalite AR-18 assault rifle (USA)

original AR-18 assault rifle, made by the Sterling Armaments of UK

the "reincarnated" AR-180B of recent manufacture. Semi-automatic only and with plastic lower receiver with integral pistol grip

Schematic view of the AR-18 (from the original Armalite patent, issued in 1968)

Caliber: 5.56x45 mm (.223 Remington M193)
Action: Gas operated, rotating bolt
Overall length: 940 mm (738 mm with folded stock)
Barrel length: 464 mm
Weight: 3.09 kg with empty 20 rounds magazine
Magazine capacity: 20, 30 or 40 rounds

The AR-18 rifle had been developed by the Armalite company (USA) by the George Sullivan, Arthur Miller and Charles Dorchester in the early 1960s. This rifle was designed for the international military market as a replacement for the AR-15 project, which had been sold to the Colt in 1959 by the Armalite's parent company, Fairchild Aircraft and Engine Corp. The AR-18 was designed as a competitor to the AR-15, which could be made at much less expenses and on simplified machinery, with the view to sell the manufacturing licenses for AR-18 to the third world countries. The AR-18 was a really successful design from a technical standpoint, but it come out too late to compete with both officially accepted and adopted AR-15/M16 rifle of American origin and already widespread AK-47 rifle of the Soviet origin. The Armalite company by itself made very few specimens of this rifle. The manufacturing license was consequently sold to the British company Sterling Armaments Co and to the Japanese company Howa Machinery co, but all three companies produced hardly over 20 000 rifles total, and the production of the AR-18 was ceased circa 1979 for some 20 years. It was originally available in the military AR-18 (selective fire) and AR-18S (selective fire, with short barrel) versions, and in AR-180 semi-automatic only version. But in the year 2001 the Armalite company resurrected the AR-180 design, in somewhat modified form. New rifle, intended mostly for the civilian and law enforcement markets, featured the same AR-18 layout and action, but discarded the stamped steel lower receiver and replaced it with the plastic lower, with AR-15-compatible magazine housing and AR-15-type trigger unit, which allowed for wider spare parts availability. The original folding buttstock and flash suppressor are replaced with the plastic fixed buttstock of the same shape and the muzzle recoil compensator, to comply with the current US firearms laws. The price of AR-180B is slightly lower than of the similar basic AR-15 type rifle, and the available user reports about AR-180B are generally quite positive.

The most interesting point about the AR-18 is that, while being a commercial failure, it served as a platform for some further development, which took place in various countries. First, the AR-18 design obviously served as a starting point for the ill-fated British SA80 / L85 bull-pup assault rifle, which can be loosely described as a bullpup-ed and weakened AR-18. Second, the AR-18 served as a starting point for the Singapore SAR-80 assault rifle, designed by the Chartered Industries of Singapore with the help of the George Sullivan (who designed the AR-18 itself). And third, the relatively new German Heckler - Koch G-36 assault rifle bears a lot of similarity internally to the AR-18.

Technical description.
The AR-18 is a gas operated, magazine fed, air cooling selective fire rifle. The gas action features a short piston stroke, rotating bolt locking mechanism. The gas chamber and piston are located above the barrel, and the piston has the cupped head and its own return spring. The square-shaped bolt carrier is mounted inside the receiver on two guide rods, with each rod carrying its own return spring. Both rods are linked by the special end plates so the whole bolt / bolt carrier / return springs / guide rods assembly can be removed from the rifle as a single unit, which greatly simplifies the field maintenance. The rotating bolt is somewhat similar in construction to the AR-15 bolt, and is rotated by the bolt pin, which is engaged in the curved cam track, cut in the bolt carrier. The charging handle is fixed to the right side of the bolt carrier and reciprocates when gun is fired.

The receiver is made from stamped sheet steel and consists of two parts - upper and lower. Both halves of the receiver are hinged one to another at the front of the receiver. The upper and lower parts are interlocked by the rear ends of the bolt carrier guide rods. AR-18 is field stripped by pressing the guide rods forward by the special lever at the rear of the receiver, then by the folding the lower receiver down and forward.

The controls consist of the trigger, safety - fire mode selector at the left side of the receiver (similar to one found on AR-15 / M16 type rifles), and the bolt stop. The available fire modes are single shots and full auto, or only single shots in AR-180 and AR-180B.

The forearm, the pistol grip and the buttstock are made from black plastic. The buttstock folds to the side to save the space, if required, and AR-15 can be fired with butt folded. The sling attachment points are located on the barrel, just ahead of the forearm, and at the butt of the pistol grip, so the sling position is not affected by the position of the foldable buttstock.

The sights consist of the hooded front post and the "L"-shaped flip-up diopter rear, also protected from sides by large "dog ears". Each AR-18 also was fitted with the scope mount at the top of the receiver by standard.