Abstract: An improved gas piston system for the automatic loading of a rifle, especially a rifle of the M-16/AR-15 type, is disclosed herein. The system employs a barrel nut, or an adaptor to a barrel nut, that has been modified to secure one end of a gas piston system. The other end of the gas piston system, namely the piston rod, engages, either directly or indirectly, the key on a bolt carrier group. This configuration positions the gas piston system at a point starting near the barrel nut and extending to the bolt carrier group of the rifle, while a gas tube extends from the gas block to the gas piston system a point near the barrel nut. Rifles of the invention are a significant improvement over rifles using both direct impingement systems and prior gas piston systems. Rifles of the invention produce significantly less deposits in the bolt carrier group and heat up less in the area of the bolt carrier group when compared to direct impingement systems.