Ruger's short-stroke two-stage piston AR-15 with quad-rail handguard and chrome-lined barrel. Rugger's answer to the piston AR trend. Type: Carbine Action: Semi-Automatic Caliber: 5.56x45mm NATO Capacity: 30 Year introduced: 2009, USA Weight: 118 oz Overall length: 35.5" Status: Active Intended use: Sport Shooting, Hunting, Home Defense