Sons Of Liberty Gun Works M4-L89 Complete Upper Features The Sons of Liberty Gun Works M4-L89 is built around a forged upper receiver mated to a Liberty Fighting Barrel chambered in 5.56 NATO giving builders a barrel known for consistent accuracy and durability. The 11.5 threaded barrel accepts the A2 flash hider that ships installed managing muzzle flash while leaving room to swap in a different muzzle device later. Sons of Liberty Gun Works designs its small parts to fit most mil-spec AR-15 lowers so this upper drops onto a standard AR-15 receiver without special fitting. The matte black finish is applied for corrosion resistance and a consistent low glare appearance across the whole upper assembly. A 10.75 L89 seven sided rail runs along the handguard giving shooters a full Picatinny mounting surface for lights lasers foregrips and other accessories in whatever position suits their setup. Because the upper does not include a bolt carrier group or charging handle builders can drop in the components they already prefer or have on hand rather than paying for parts they will replace. This makes the M4-L89 a practical option for anyone upgrading an existing rifle building a dedicated range gun or assembling a rifle for competition. Builders looking for a forged mil-spec compatible 5.56 upper will find this Sons of Liberty Gun Works M4-L89 for sale at GrabAGun. Sons Of Liberty Gun Works M4-L89 Complete Upper Specifications Manufacturer: Sons of Liberty Gun Works Model: M4-L89 Complete Upper Type: Upper Receiver Caliber: 5.56 NATO Barrel Length: 11.5 Barrel Type: Threaded Fit: AR-15 Color: Black Finish: Matte Rail: 10.75 L89 Rail Muzzle Device: A2 Flash Hider Available At: GrabAGun