Mitchell Defense The DOC AR-15 .300 BLK 10.3in Upper Receiver Chrome-Moly Barrel Black Finish Quad Rail Handguard. 3in .300 Blackout Upper Receiver is optimized for suppressed and unsuppressed reliability with both subsonic and supersonic ammunition. The billet 7075-T6 upper includes a thermal-fit barrel seat that enhances barrel alignment and accuracy. The 10.3in barrel offers balanced rigidity and reliable ballistic performance. A standard adjustable gas block allows fine-tuning of cycling behavior to match suppressor setups or load variations. The ArmorLube Carbon Cutter BCG with Carpenter 158 HP/MPI bolt improves reliability and reduces fouling. A free-float M-LOK handguard provides versatile accessory mounting. Finished in E-Series Cerakote. Specifications for Mitchell Defense The DOC AR-15 .300 BLK 10.3in Upper Receiver: Manufacturer: Mitchell Defense Caliber: .300 AAC Blackout Overall Length: 21 in Barrel Length: 10.3 in Barrel Profile: Standard Gas System Length: Carbine Length Barrel Twist Rate: 1-7 Firearms Threads Per Inch: Non Threaded Muzzle Device: A2 Flash Hider Finish: Nitride Gun Model: AR-15 Fabric/Material: 4150 CrMoV Gun Make: AR Platform Bolt Carrier Group Included: MIL-SPEC Charging Handle Included: MIL-SPEC Features of Mitchell Defense The DOC AR-15 .300 BLK 10.3in Upper Receiver Adjustable gas block enables precise tuning for ammunition and suppressors Thermal-fit billet upper enhances stability and accuracy ArmorLube Carbon Cutter BCG with C158 HP/MPI bolt ensures dependable cycling M-LOK handguard provides lightweight modularity Package Contents: Mitchell Defense The DOC AR-15 .300 BLK 10.3in Upper Receiver What firearm models does the manufacturer say Mitchell Defense The DOC AR-15 .300 BLK 10.3in Upper Receiver is compatible with? The manufacturer says that Mitchell Defense The DOC AR-15 .300 BLK 10.3in Upper Receiver is compatible with AR-15Mitchell Defense 421122: The DOC AR-15 .300 BLK 10.3in Upper Receiver Chrome-Moly Barrel Black Finish Quad Rail Handguard