The Aero Precsion M5 308 Lower Receiver allows you to build a custom big-bore AR from the ground up. Mil-spec dimensions and coating ensure the highest quality and correct component interface. Receiver fits DPMS pattern components, including magazines and upper receivers. Machined from 7075-T6 aluminum, and finished with a matte black hard-coat anodized Mil 8625 Type 3 Class 2 finish. Rear takedown pin detent hole threaded 4-40 to allow for a set screw to retain the takedown pin. Bolt catch is threaded for a screw pin, so that no roll pin is needed. Integrated trigger guard and selector markings that function with 45, 60 or 90 degree safety selectors.&n Mfg: Aero Precision SPECS: Fits - Gen 1 DPMS 308 components, including magazine and upper receiver.