About the BCMA(R) MK2 Standard 16" 300 BLACKOUT Complete Upper Receiver w/ KMR-A15 Handguard BCMA(R) 300 Blackout Upper Receiver Groups Continuous taper barrel profile designed for optimal weight, balance, and performance. Tapered barrel profile out front, for easier maneuverability. No sharp handguard cap shoulder for improved barrel harmonics and improved accuracy. Muzzle threaded in standard 30 cal (5/8x24). Included with this complete upper group: KMR-A15 KeyMod(TM) Handguard. KMSM (KeyMod(TM) Sling Mount) One 3" Picatinny Rail Section BCMA(R) Comp Mod 1 - 762/300 BLK Featuring BCM's Patented MK2 Upper Receiver This proprietary design offers enhanced rigidity over the USGI product. The increased rigidity limits barrel deflection which aids in consistency/accuracy. Less flex also reduces premature damage, wear, and failure of bolt lugs from misalignment. A gas expansion chamber is machined above the charging handle track, combined with dual vents machined at the rear (each side, above charging handle latch) help to redirect and vent gas away the shooters face. U.S. Patent Numbers: 10670355, 10677549, D888182 BCMA(R) has taken great care to ensure the best possible performance and interchangeability. However, due to the large operational range of 300 Blackout ammunition in the market place, BCMA(R) cannot guarantee function will all ammunition types in all conditions. These barrels were designed to run with a H3 buffer with high velocity ammo. If running subsonic ammunition, it is recommended to run your suppressor and a carbine buffer. Fine tuning may be required in limited instances based on ammo and buffer choices that work best for the desired application. BCMA(R) also recommends running the Crane O-ring (provided with all BCMA(R) Bolt Carrier Groups) over the extractor with 300 Blackout. Specs: Caliber: 300 Blackout Barrel Length: 16.1+" Barrel Material: 11595E Spec Steel Barrel Finish: Manganese Phosphate per Mil-Spec Bore & Chamber: Chrome Lined Weight: 3 lbs Twist Rate: 1:7 Gas System: Pistol Muzzle Device: BCMA(R) Comp Mod 1 (762/300BLK) Muzzle Threads: 5/8x24 Handguard: KMR-A15 Shop Related Products: Want to see more upper receivers? Click the links below to view more BCMA(R) AR complete uppers! 300 BLACKOUT Complete Uppers AR-15 Complete Uppers w/ KeyMod(TM) Handguards 16" Recce Mid Length AR-15 Complete Uppers BCMA(R) MK2 AR-15 Complete Uppers All BCMA(R) AR-15 Complete Uppers Bravo Company builds: Life Saving Tools(TM) Copyright 2023 Bravo Company MFG, Inc.