It is also not a give that shooting a slug through a full choke bbl is going to damage it. Several slug designs took into consideration they were apt to be fired from full choke guns & were designed to be capable of passing through them without damage to the gun. Better accuracy is generally obtained through a more open choked bbl however. Also many doubles will not put a slug from the two bbls to the same point of impact, one simply has to try & see. The old Ithaca Derslayer bbls were reputed to be quite accurate with slugs (I never owned one) & they were bored undersize to a cyl bore of about the dia of a normal full choke for their entire length.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra