The Remington Defense R4 RGP Rifle is a new take on an already proven design. The core of this AR-platform is the gas piston operation system. This piston drastically improves the rifle’s reliability as well as reducing the heat generated while firing and helps keep the mechanism clean. In addition the R4 comes equipped with an Advanced Armaments 51-tooth mount three prong flash hider. The Remington Defense R4 RGP gas piston semi-automatic rifle features: Ambidextrous Charging Handle Advanced Armament 51-Tooth Mount Gas Piston System Monolithic Upper Receiver Remington Defense R4 RGP 5.56 16.5 Rifle 86580