I have a Franchi Affinity 12-ga which is Made in Italy and Imported by Benelli . It came with F, M. and IC chokes . I emailed Benelli about the use of what chokes to use with Steel shots and their reply was IC or M were fine but do not use Steel with a Full choke . As mentioned above can cause permanent damage to my barrel . I can't say this to be true with a Fixed Full Choke but I would guess it not to be safe for the same reason as with my Franchi Affinity .
Just enjoying life best I can honestly and honorably .