Pattern with full choke, 16 yds, look only at the target (dot the size of a 0.25 cent piece) 3 shots that should over lap. To move the poattern center 1" in the direction you want, move your stock 1/16th inch in the same direction (the Churchill mehtod). Hope you have an adjustable comb. Your shooting form also affects this. Hope this helps.
Actually, I have found that patterning from a rest can make the gun shoot left. I don't know why. Try standing at 13 yards and shoot at a dot that you come up on from 6 o"clock just as if were a straight from 3. Shoot when the bead hits the dot. The vertical movement will eliminate a lot of the horizontal wiggle.
This method will replicate your firing reaction as though you were shooting a target. I think you will find it instructive.
Thanks for the advice brooks, and what i meant by the pattern being half to the left was that once i took half that should be left i got another half of the patter over and that is what i meant by the pattern being to the left. Almost my whole pattern is to the left. There is probably about 5% of ym pattern to the right of the target.
First, make sure your gun is shooting to the left. From a rest, shoot at least 5 shots at 5 different 13 yard targets. Ten shots may be better. Carefully align the center bead with the front sight. In this test, shoot the shotgun like a rifle. You will probably pull off around one out of five shots. Do not consider the shots that you jerk to the left or right.
If your gun shoots to the left with the sights lined up, moving the comb to the left or right will not help. Moving the comb laterally is useful to keep your eye aligned with the rib and front sight, but if they are already aligned, then there is nor reason to misalign them by moving the comb.
If your gun truly shoots to the left, you can have a custom choke tube made, bend the barrel or send the gun to a good barrel man.
I do exactly as Pat suggests when I'm checking out a new gun (or a reworked one), except I do it at 20 yards. I find it much easier to see what is going on if I have a bit of an actual pattern as opposed to a large hole.
I had the same problem as you with my Beretta 682 Gold E combo. It turned out only 2 of the 6 choke tubes that came with the gun shot to the same POI. You'll have to determine if your choke tubes are a problem before you can determine anything else. Just put your tightest choke in any barrel and shoot from a rest until you can determine its POI. The do the same for every other choke you have, using the same barrel. It is important to use the same barrel when testing choke tubes, because if you put an eccentric choke in another barrel it won't line up the same way and the POI will be off in a different direction. Mark and discard the ones that shoot to different POIs. I replaced my bad tubes with Briley's (on sale at the time) and had no further problems.
Once you have known good chokes to work with you can determine if you have barrel problems (misalignment, choke bores off-axis, etc.).
I disagree with Pat - a little. Moving the comb left and right will change you POI left and right as well. Who said the beads came aligned from the factory?
The gun has to shoot where you look - you're not aiming, you're pointing a shotgun. Remove the center bead or learn to recognize the offset between the center and front when you mont your gun (or have it moved to align). Once the gun is mounted, you shouldn't be worried about the beads anyway.
Custom chokes will work, but moving/removing the bead is a lot cheaper and just as effective.
Joe- If the mid bead is lined up with the front bead, moving the comb to the right or left will only cause them to become out of alignment.
I agree with you that you should not aim with the front bead, but checking the alignment between the mid bead and the front sight is useful now and then to make sure you are mounting the gun consistently.
I've posted this before, but here you go again. This is a 391 project gun of mine that truly was shooting left. I bent the barrel and now it shoots perfectly straight (No, I do not offer this service. I only do my own guns and close friends).