I shot my 1911 Commander this evening from 50' for the first time. I was practicing for shooting Combat at my local range. (From 20' I was okay). All my shots were to the left of center. I had the range officer try and he had the same problem. How does one adjust the rear sight to correct the shots? My gun is a Mark IV, series 80 Commander. The rear sight is dovetailed in. Can I tap with a brass hammer? Which way do I move to correct the shots being to the left of center?