The Frontline QR-10.5 is equipped with a 10.5-inch carbine-length barrel chambered in 5.56. The barrel and low-pro carbine gas system are protected by Anderson's 9.5 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). This rifle also hosts an H2 weight buffer system Magpul K2 Grip and BSL Arm Brace. - 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 10.5 inches - Barrel Finish Nitride - Twist Rate 1:7 - Gas System Length Carbine 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 9.5 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