The Sons of Liberty Gun Works M4-L89 Upper Receiver Group (brand part no. U-M4L89-556-115-A2) is a complete 5.56 NATO upper built around an 11.5-inch Liberty Fighting Barrel, an L89 seven-sided rail, and a forged upper receiver, finished with an A2 muzzle device. Sons of Liberty Gun Works builds duty-grade rifles and parts, and this URG drops onto any mil-spec lower for a fast, proven build. Among AR barrels and upper assemblies, an 11.5-inch fighting upper is the classic compact-carbine configuration.

Key Specifications

• The chambering is 5.56 NATO.
• The barrel is an 11.5-inch Liberty Fighting Barrel.
• The rail is the L89 seven-sided design.
• The upper receiver is forged for strength.
• Ships with an A2 muzzle device installed.
• Fits mil-spec AR lowers as a complete drop-on group.

Frequently Asked Questions

Is this upper itself regulated? No, an upper receiver group is an unregulated part. Because the barrel is 11.5 inches, install it on a pistol lower or an ATF-registered short-barreled rifle — putting it on a standard rifle lower would create an unregistered SBR.

Will it fit my lower? Yes, it drops onto any mil-spec AR-pattern lower receiver.

Buy the SOLGW M4-L89 Complete Upper

A duty-grade 11.5-inch 5.56 upper ready to drop on your build is exactly what this M4-L89 group delivers. Order it from our Lubbock, Texas gun shop for fast shipping.