Weighing 7.3 ounces, the R-10 magnesium Lightweight Lower Receiver is the lightest production LR308 lower on the market. For use with large calibers like .308 Winchester/7.62x51mm NATO and 6.5 Creedmoor, amongst others. The R-10 is DPMS GEN 1 compatible and is designed with a tensioning screw, to ensure a secure fit with your upper, and a bolt catch screw in place of a roll pin. Protected with Tagnite and Cerakote, the R-10 Lower Receiver is the best choice for your ultra-light weight large caliber AR build.