The Aero Precision M5.308 Complete Lower Receiver is the perfect base for your custom big-bore AR rifle. This complete lower DOES NOT come with a stock, allowing you to pick the one that best fits you. Works with standard AR 308 components and magazines Rear takedown pin detent hole is threaded for a 4-40 set screw Bolt catch is threaded for a screw pin (no roll pin needed) Integrated trigger guard Selector markings will work with 45, 60 or 90 degree safety selectors Accepts Battle Arms Development short throw safety selectors, but will work with any standard selector No gap with aftermarket pistol grips M5 (.308) Lower Receiver Mag Mfg: Aero Precision.