It would be a hell of a lot cheeper to fit excentric bushed firing pins than to machine excentric barrels.

PS you cannot "reload to regulate" unless the barrels have been regulated to shoot together with some specific but unknown load in the past. Once it has been done you can reload to find this for want of a better word "sweet spot" or regulation load. You cannot get two barrels that bear no common POI to shoot together by loading alone.

Regards