The factory chokes are not designed to be shot with steel shot. They constrict way too fast. Steel does not compress like lead does when constricted by a choke and there fore you need a much longer and more gradual constriction. If you look through the catalogs you will see that all of the steel shot chokes are much longer than O.E. chokes. You need to get an after market choke to shoot steel shot.

It will probably not happen immediately but if you shoot much steel shot with the factory chokes you will eventually bulge out or blow out the end of your barrel and it will need to be cut off and rethreaded for choke tubes.