The Frontline QR-16 is equipped with 16 mid-length barrel chambered in 5.56. The QR-16 features a 12 Free-Float Quad-Rail Handguard with Picatinny rails located at the 12 3 6 and 9 o'clock positions throughout the length and four QD sling sockets at the 3 and 6 positions (two on each side front and rear of rail). - Anderson's Frontline Series is a diverse collection of American Made firearms built to adapt to any mission. A derivative of Anderson's Law Enforcement exclusive lineup Defender Series we've collected all the data gathered from the rigorous training evolutions and tedious accuracy testing to compile this rigid duty-driven rifle series for the civilian market. These rifles are finely tuned with adjusted buffer weights that complement their respective gas systems to ensure low recoil impulse. This series features Anderson's TRS handguards and free-float quad rail systems to ease your transition from mission to mission. The integral Magpul furniture supports shooter ergonomics while staying tight to your firearm enhancing your tactical approach. - Weight 8 - Caliber 5.56 NATO - Lower Receiver Material Forged 7075 T6 Aluminum - Upper Receiver Material Forged 7075 T6 Aluminum - Upper Receiver Finish Type 3 Hard Anodized Black - Lower Receiver Finish Type 3 Hard Anodized Black - Trigger Guard Open Trigger - Bolt Carrier Finish Nitride - Bolt Carrier Material 8620 Steel - Bolt Finish Nitride - Bolt Material 9310 Steel - Barrel Material 4150 Chrome Moly Vanadium - Barrel Length 16 inches - Barrel Finish Nitride - Barrel Contour Medium - Twist Rate 1:7 - Gas System Length Mid Length - Gas System Type Low Profile - Gas Block Diameter .750 inch - Charging Handle Breek Arms Warhammer Ambidextrous - Bolt Carrier Group Standard M16 Profile - Hand Guard Type M-Lok - Handguard M-Lok - Hand Guard Length 12 inches - Pistol Grip Magpul K2 - Thread Pattern 1/2-28 - Muzzle Device A2 Flash Hider - Buffer Tube 6 Position Buffer Tube - Butt Stock/Brace MOE SL Carbine Stock