If it's a barrel regulation issue, changing the cast will change the POI of both barrels. You can't change the POI of one barrel only by adjustments to the stock. Bending the stock from "cast off" to neutral will move the POI to the left for both barrels.
If the left barrel is spot on, and trigger pull on the right barrel is not an issue, you might want to consider letting Briley put choke tubes in the right barrel only that will alter the point of impact. I think they call them "eccentrix" choles or something like that. I had to do that with an AYA recently for the same problem.
Anyway, my two cents.
Hack
