While there is not one factor that distinguishes the so-called commercial from the military model, the commercial model is usually blued. It commonly has a fixed front sight and a rear sight with no retaining screw. It often has 28 fins on the barrel, a one piece magazine release, no outward flanges on the safety/selector switch, and no sling swivels. Lastly, the commercial model commonly has a smooth take-down screw, a two-hole trigger guard, and serial numbers ranging from one to 20,000.