With Eugene Stoner's AR-15 rifle design firmly entrenched as the M16 under production by Colt, his Armalite firm turned to the design and production of a similar yet simplified version of their AR-15 design, moreso to license this version out for production in Third World markets. As the base AR-15 proved to be too difficult to manufacturer without the need for complex production facilities (it relied on aluminum forgings in its construction), the AR-18 was to be the "budget" assault rifle alternative in a market where the 5.56x45mm NATO cartridge was becoming as readily-available as the 7.62x51mm NATO type.
The gas-operated AR-18, looking every bit like its AR-15/M16 cousin, was produced with simplicity in mind utilizing plastic components and steel metal pressings throughout. Along with this cost-cutting approach, general operation of the weapon was kept to minimal expectations resulting in a reliable weapons system that was easy to maintain. The AR-18 was chambered to fire the 5.56x45mm cartridge and came with a foldable plastic butt. Magazines were also offered in 20-, 30- and 40-round counts with the system reporting a cyclic rate of fire of 700-800 rounds-per-minute.
As the United States military had already settled on the M-16 (AR-15) as its primary assault rifle, this left the AR-18 to attempt to find success on the global stage. The rifle would find a market niche through the UK-based Sterling Armaments concern and net its first quantitative sale. From then on, more foreign outlets began producing the system in more localized forms ensuring that the AR-18 would live on with various forces around the world.
AR-18 manufacturing spanned from 1969 to 1978. Armalite brought the AR-18 back into the fold in 2002 under the designation of AR-180B.