Sons of Liberty Gun Works M4-L89 Features The Sons of Liberty Gun Works M4-L89 upper receiver group is built around a Liberty Fighting Barrel chambered in 5.56 NATO with a 14.5 inch barrel and a pinned and welded ASR flash hider bringing the overall length to a legal 16 inches without sacrificing the shorter more maneuverable handling of a carbine-length barrel. The forged upper receiver provides a durable foundation for a custom AR-15 build holding tight tolerances for reliable function with a wide range of bolt carrier groups. This upper does not include a BCG or charging handle so it is best suited for a builder assembling a complete rifle from select components. A 13.75 inch L89 seven-sided rail gives the shooter a slim modular handguard with mounting surfaces spaced around its circumference for lights lasers and other accessories wherever they are needed. The matte black finish provides a durable low-maintenance exterior that resists wear from handling and field use. Because the upper is built to mil-spec dimensions it mates directly to a standard AR-15 lower receiver without additional fitting. For builders looking to complete an AR-15 with a purpose-engineered barrel and modern rail system the Sons of Liberty Gun Works M4-L89 upper delivers a reliable ready-to-assemble foundation. Sons Of Liberty Gun Works M4-L89 Upper Receiver Group Specifications Manufacturer: Sons of Liberty Gun Works Model: M4-L89 Upper Receiver Group Type: Complete Upper Caliber: 5.56 NATO Barrel Length: 14.5 Pinned (16 OAL) Handguard: 13.75 L89 Rail Finish: Matte Color: Black Compatible Hosts: AR-15 Available At: GrabAGun