AR 15

Full assembled model of AR-15 rifle with 30 round mag and 5,56 mm Nato bullet.

An AR-15 style rifle is a lightweight semi-automatic rifle based on the ArmaLite AR-15 design, which is itself a scaled-down derivative of Eugene Stoner's AR-10 design. ArmaLite sold the patent and trademarks to Colt's Manufacturing Company in 1959. After Colt's patents expired in 1977, Colt retained the trademark and is the exclusive owner of the AR-15 designation. While most earlier breech-loading rifles had a single receiver housing both the trigger and reloading mechanism, an innovative feature of the AR-15 was modular construction to simplify substitution of parts and avoid need for arsenal facilities for most repairs of malfunctioning military rifles.