The 6mm ARC (Advanced Rifle Cartridge) was designed to deliver excellent ballistic performance in AR15 platform rifles that rivals the extended range performance of larger rounds typically chambered in the larger AR10/LR308 style rifles. The combination of our Br4 platform which delivers little recoil and this flat shooting round makes a great choice for hunters and extended target shooters looking for predictable performance. - Platform Br4 - Caliber 6mm ARC - Operating System Compact Action-Direct Impingement - Barrel Length 16.1 - Barrel Twist 1:7.5 - Barrel Contour MT - Barrel Material 4140CM SBN - Barrel Twist 1:7.5 - Muzzle Device CMMG ZEROED Muzzle Brake - Muzzle Thread 5/8 x 24 - Gas Port Location Rifle - Gas Block Adjustable 0.750 - Upper Receiver DISSENT 7075 T6 Aluminum - Lower Receiver Br4 Billet 7075 T6 Aluminum - Hand Guard CMMG 15 Proprietary - Finish Cerakote - Charging Handle Dissent Side Charger- Reversible - Stock / Brace Magpul SGA- Remington 870 - Trigger Type ZEROED Drop-In Single Stage - Trigger Guard Integrated - Safety Selector Reversible Cross Bolt - Magazine (2) CMMG 10rd - Weight 8 lbs - Length 38.1