Mitchell Defense DOC 10.3in 5.56 NATO Upper Receiver Cold Hammer Forged Chrome-Lined Barrel Black Finish M-LOK Free-Float Handguard. 3in CHF 5.56 NATO Upper Receiver is engineered for duty-grade reliability with a 7075-T6 billet upper and thermal-fit barrel seat for enhanced rigidity and accuracy. The cold hammer forged chrome-lined barrel withstands high firing schedules with exceptional heat tolerance and bore longevity. The ArmorLube Carbon Cutter BCG built around a Carpenter 158 HP/MPI bolt provides smooth cycling and high resistance to wear. A lightweight M-LOK free-float handguard offers stability and accessory adaptability while the E-Series Cerakote finish protects against harsh environmental conditions. This upper is designed for users needing a robust compact 5.56 platform optimized for professional use. Specifications for Mitchell Defense The DOC AR-15 5.56mm NATO 10.3in Upper Receiver: Manufacturer: Mitchell Defense Caliber: 5.56x45mm NATO Overall Length: 19 in Barrel Length: 10.3 in Barrel Profile: Standard Gas System Length: Carbine Length Barrel Twist Rate: 1-7 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 5.56mm NATO 10.3in Upper Receiver Thermal-fit billet upper receiver enhances accuracy and structural strength ArmorLube Carbon Cutter BCG with C158 HP/MPI bolt improves cycling reliability Lightweight M-LOK handguard for rigid accessory mounting Ideal compact 5.56 platform for duty training or defensive roles E-Series Cerakote for long-term environmental protection Package Contents: Mitchell Defense The DOC AR-15 5.56mm NATO 10.3in Upper Receiver What firearm models does the manufacturer say Mitchell Defense The DOC AR-15 5.56mm NATO 10.3in Upper Receiver is compatible with? The manufacturer suggests that Mitchell Defense The DOC AR-15 5.56mm NATO 10.3in Upper Receiver is compatible with AR-15Mitchell Defense 422111: DOC 10.3in 5.56 NATO Upper Receiver Cold Hammer Forged Chrome-Lined Barrel Black Finish M-LOK Free-Float Handguard