Sons of Liberty Gun Works M4-L89 5.56 Barreled Upper - 11.5" - A2

The Sons of Liberty Gun Works M4-L89 11.5-inch barreled upper receiver group builds on the EXO3 platform's foundation with the Drivelock barrel nut system, integral steel QD cups at the barrel nut, and an internal dowel pin between the upper receiver and rail — a more mechanically rigid upper assembly designed for duty use and minimal point-of-impact shift with attached laser or VAS systems, with A2 flash hider muzzle.

The SOLGW M4-L89 11.5-inch barreled upper is a complete upper receiver group chambered in 5.56 NATO, featuring a 11.5-inch Liberty Fighting Barrel, a forged upper receiver, a 4140 steel gas block with nitrided gas tube, and a 10.75-inch L89 seven-sided M-LOK handguard with the Drivelock barrel nut system and integral steel QD cups. Muzzle: A2 flash hider. BCG and charging handle not included. Test fired before shipment.

The L89 represents SOLGW's premium upper receiver group platform, incorporating three mechanical refinements over the EXO3 that specifically address the needs of operators running laser aiming modules and other VAS accessories where point-of-impact stability between sessions matters. The Drivelock barrel nut system is engineered for more consistent, repeatable torque and a more rigid handguard-to-upper connection than standard barrel nut designs, reducing the flex and micro-movement at the handguard-upper interface that can cause small POI shifts when accessories are stressed during movement and field use. The internal dowel pin between the upper receiver and rail provides an additional mechanical interface that locks the handguard's rotational and lateral position relative to the upper receiver, adding a second retention mechanism beyond the barrel nut alone. The integral steel QD cups at the barrel nut on both left and right sides provide purpose-built, hardened sling attachment points without requiring a separate QD socket at the handguard — the steel construction resists the wear that aluminum QD sockets develop under sling load cycling over time. The seven-sided M-LOK slot configuration and anti-rotation tabs are shared with the EXO3 platform. The Liberty Fighting Barrel and 4140 gas block with nitrided gas tube are SOLGW's standard upper components, assembled to the same standards as their complete rifles and test fired before leaving the shop.

Caliber: 5.56 NATO. Barrel: 11.5 inches, Liberty Fighting Barrel. Rail: 10.75-inch L89 M-LOK, seven-sided, Drivelock barrel nut, integral steel QD cups both sides. Gas block: 4140 steel, nitrided gas tube. Muzzle: A2 flash hider. Upper: forged mil-spec. BCG and charging handle: not included. Test fired before shipment.

Drivelock barrel nut system and internal dowel pin provide a more rigid upper-to-handguard connection with reduced micro-movement — designed for minimal POI shift with attached lasers and VAS systems. Integral steel QD cups at barrel nut on both sides provide hardened sling attachment without separate hardware. Test fired at the shop before shipment.

The right barreled upper for duty operators running laser aiming modules or VAS systems who need maximum mechanical rigidity and minimal POI shift — SOLGW's L89 Drivelock platform in a 11.5-inch 5.56 configuration, test fired, without BCG or charging handle.