The Rock River Arms LAR-15 Mid-Length A4 is a mid-length gas system AR-15 with a 16-inch barrel, flat-top upper, and RRA's factory two-stage National Match trigger. The mid-length gas system reduces bolt carrier velocity and felt recoil compared to carbine-length systems on 16-inch barrels. A4 configuration denotes the flat-top upper receiver for optics mounting. Type: Rifle Action: Semi-Automatic Caliber: 5.56 NATO Capacity: 30 Year introduced: 2004, USA Weight: 6.3 oz Overall length: 32" Status: Active Intended use: Sport Shooting, Tactical