I have always wondered what Sigs Nitron finish was all about. In a recent article I was reading about the Legion finish the writer stated, "All Legion guns are finished in SIG’s gray PVD, which stands for Physical Vapor Deposition. It is a process whereby a protective coating in the form of a metal vapor is applied to a metal surface by ion bombardment or heat evaporation while in a vacuum. It results in an extremely durable, hard (about 70 on the Rockwell scale) and uniform compound; and, in the Legion’s case, it results in a matte gunmetal-gray color that resists rust and wear. (On other SIG guns, black is added to the PVD process and the company calls the coating Nitron".