Piston-driven AR-15 with a 16-inch nitride-treated barrel and Adams Arms patented micro-size adjustable piston system. Forged 7075 upper and lower. One of the most established piston AR manufacturers in the US market. Type: Rifle Action: Semi-Automatic Caliber: 5.56x45mm NATO Capacity: 30 Year introduced: 2012, USA Weight: 6.4 oz Overall length: 35" Status: Active Intended use: Patrol / Range