Based on the info that I have, the only Combat Master stamped with its "Mark number" is the Mk. VI. The Mk. I is matte blued chrome moly, the Mk. II is nickel plated CM, the Mk. III is hard chromed CM, the Mk. IV is blued, with the sides of the slide polished, the Mk. V is matte stainless, and the Mk. VI "Professional Model" has the sides of the slide polished. The Mk. VII looked mostly like the Mk. V, but without any sights. The Mk. VII's also appear to have slides made by Caspian; the cocking serrations are of the square, Caspian style rather than the saw-tooth type seen on the other models. The later MC-1 looks identical to the Mk. V, but I'm basing that on a catalog photo.