Ruger introduced its new SR-556 rifle at last year's National Rifle Association show in Phoenix. The announcement ended years of speculation that Ruger was indeed working on an AR-style rifle, and the SR-556 quickly became the buzz of the show. While the newest Ruger long gun possesses many typical AR features, it also has a Ruger-designed piston drive system. The patent-pending, chrome plated two-stage piston system provides a cleaner, cooler running, and more reliable operation than any standard AR gas impingement system can deliver. Read our full review of Ruger's SR-556.