Chuck,

I had the same problem with the right barrel on a 20 ga SxS a few years ago but mine was hitting about 6" to the right.I took my cardboard patterns to Steve Power at Briley Mfg in Houston and they some how adjusted the choke in the right barrel and when I got it back both barrels were hitting where they were supposed to.I can't remember how much it opened the choke but I know it wasn't very much.

Hope this helps - - Good Luck