Depending on how much metal/choke you have in that area, you could have a gunsmith eccentrically hone the chokes (similar to installing eccentric choke tubes). Just putting choke tubes into the bbls may not solve your problem, since they should be installed parallel to the existing muzzle line. Briley can advise you on either option. You'll need to be able to tell them how far off of center the offending barrel(s) is/are. Most expensive option would be to strip the ribs and relay them. Spanish gun barrels for the most part are brazed so this isn't possible; only soft soldered barrels can be fixed that way.
Good luck, this problem has been the bane of my existence lately.....test firing for regulation is the only peace of mind when entering into a purchase.
V/r
Maxey
