I have a Mk 1 that I carry, and shoot in IDPA matches. Out of the box, it shot OK, but not for very long. After about 20-30 rounds, it would start to mis-feed and fail to eject. I replaced all of the springs, including the mag spring, and polished the internals in the more-or-less standard 1911 areas, and the gun has since run like a champ. As luck would have it, the only parts that show any wear are the parts that are peculiar to the Combat Master, that can't be readily purchased or converted from similar 1911 parts - the guide rod and reverse plug.