Ballistic Advantage BA15 Enhanced, Semi-automatic, Stripped Lower Receiver, .223 Remington/556NATO, Matte Finish, Black BAPA100083 The Ballistic Advantage AR15 Enhanced Lower Receiver delivers billet aesthetics in a forged package. This custom designed enhanced forging is machined from 7075-T6 Aluminum and compatible with all mil-spec AR15 parts. Aside from the visual upgrades this custom engineered design provides that challenge much more expensive billet options, Ballistic Advantage has added several functional features to the lower receiver to simplify the assembly process for the at home builder.