Further to this discussion, IMHO the conversion of shotgun actions to striker (firing pin) bushings from the original integral tumbler/striker combination weakens the action. A significant amount of metal was removed when the action was made (in the back of the action standing breech) and taking significantly more metal out in the front of the standing breech for the said conversion is not something that I would do and expect the standing breech to remain square to the barrel face while firing 35,000 to 40,000 psi rifle cartridges.

Find you a BRNO zp49 or some other 3rd fastner action with striker bushings. Browning BSS's seem to be a choice even without 3rd fastner.