With subsonic and supersonic loadings available for self-defense hunting and target shooting 300BLK is one of the most adaptable cartridges out there today. No matter how you plan to use your Br4 this .30 cal carbine packs practicality like the full length top Picatinny rail and M-LOK handguard with unmatched style. - Platform Br4 - Caliber .300 BLK - Operating System Compact Action-Direct Impingement - Barrel Length 16.1 - Barrel Twist 1:7 - Barrel Contour MT - Barrel Material 4140CM SBN - Barrel Twist 1:7 - Muzzle Device CMMG ZEROED Muzzle Brake - Muzzle Thread 5/8 x 24 - Gas Port Location Carbine - 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) Magpul 10rd PMAG - Weight 7.8 lbs - Length 38.1