Originally manufactured as an AR-180 semi-automatic rifle by Sterling for Armalite, this rifle was upgraded to full automatic by Pearl Manufacturing. Armalite's follow-up to the AR-15, the AR-18/180 failed to gain deep market penetration, though many of the features (piston drive operation, ambidextrous fire controls, and a folding stock) would become popular upgrades to the 15 in later years. Adjustable post front and two-leaf peep rear sights, with a three prong flash hider and British commercial proofs on the barrel, ribbed and ventilated handguard, integral scope block on the AR-180/Sterling marked upper receiver, and the Pearl "PMC" mark on the left side of the lower receiver. The selector stops on the lower position have been cut down and rewelded to permit three-position operation, with "AUTO" added to the appropriate area, and the interior of the upper receiver has been cut and reshaped to house the safety sear. Fitted with a smooth pistol grip and a side folding buttstock with ribbed buttplate. Magazine absent.