Grey Ghost Precision AR-15 Receiver, Billet, Semi-automatic, Stripped Lower Receiver, Matte Finish, Black GGP-556-LR The MKII version of the GGP-S Series brings a new level of customizability never before seen in our rifle receivers. Not only can you build your own version of the Heavy or Light rifle, but you can use your favorite aftermarket parts to complete the weapon of your dreams. GGP Billet Receivers are precisely machined from 7075-T6 Aluminum for a perfect fit. The lower receiver includes their ambidextrous bolt release as a standard feature, as well as a flared magwell and integral trigger guard. Start your build off right.