I always figured any gun made after the mid-70's was probably ok for steel if it wasn't choked super tight. Some gun companies have an actual cut off date that they'll tell you if you ask. Years ago I called Browning about a BSS I was looking at and they said it was fine for steel since it was made after a certain year. I can't remember the year unfortunately. I believe Remington has the same kind of thing as well.

DLH

Out there at the crossroads molding the devil's bullets. - Tom Waits