I am not a gun fitting pro but I will try to answer your question. With a shotgun, the rear sight is your eye. A properly fitted shotgun will fire the center if its shot pattern where the shooter is looking. If the pattern is not centered where the shooter is looking, the stock must be modified. This is how I have gone about this.
1. Practice with your new gun to develope a consistant gun mount. This is very important and may take a while. The butt-to-shoulder and comb-to-face positions must be consistant for each shot.
2. Pattern fire your gun at 30yd. A 30in sheet of butcher paper with a 2in black spot mounted on a target frame will do. Start by firing five shells through a full choke pointing at the 2in black spot.
3. Look at the pattern. If the pattern center is higher or lower than the black spot, adjust the pitch. If the pattern center is left or right of black spot, adjust the cast.
4. Repeat the procedure with some of your other choke tubes.
A propperly fitted shotgun will pattern where you are pointing and will have less felt recoil. For more details on gun fitting from champion shooters, check the forum on Shotgun World. Good luck.
