How well do you do with factory ammo? Any barrel leading/fouling? If the bullets aren't undersize, I'd say practice, pratice, practice. Handguns react to recoil differently when shot from a rest. A hard rest will throw the shots off much easier than a soft rest or handheld. Trigger control is essential for consistant pistol shooting. Here's a symptom chart for handguns, may help;
http://www.pointmanspage.com/gallery...hart.jpeg.html