Sons of Liberty Gun Works M4-L89 .300 BLK 8.5" Bbl L89 Rail A2FH Liberty Fighting Bbl & Mil-Spec Upper Receiver U-M4L89-300-85-A2

The Sons of Liberty Gun Works M4-L89 .300 BLK Barreled Upper is a compact, mission-specific assembly designed to maximize the performance of the .300 Blackout cartridge in a short-barreled configuration. It features an 8.5-inch Liberty Fighting Barrel with a pistol-length gas system, providing the ideal dwell time for reliable cycling with both subsonic and supersonic ammunition. The system is built around the L89 Drivelock handguard, which utilizes a titanium barrel nut and a specialized three-point locking mechanism to ensure the rail remains perfectly indexed, preventing rotation and maintaining zero for rail-mounted lasers or optics. Finished in a rugged hardcoat anodized black and capped with a standard A2 flash hider, this upper is an elite choice for specialized close-quarters or suppressed builds. Sons of Liberty Gun Works M4-L89 .300 BLK 8.5" Bbl L89 Rail A2FH Liberty Fighting Bbl & Mil-Spec Upper Receiver U-M4L89-300-85-A2