The Sons of Liberty Gun Works AR-15 Upper receivers are built from mil-spec 7075-T6 forgings from the lead forge in the U.S. They contour is fully machined leaving no flash marks from the forging. We take extra care when machining our upper receivers resulting in tolerances that are tighter and fits that are better than other upper receivers. We use mil-spec Matte black hard-coat anodized Mil 8625 Type 3 Class 2 finish. Try one today and feel the difference.