I thought of something else; you' ll have to check the manufacturers sites because I think on the 3 1/2' ' combos the slug barrel is still 3' ' . I don' t believe there are any 3 1/2' ' slugs out there. I think they want the 3' ' barrel with the combo so you don' t shoot 2 3/4' ' and 3' ' slugs out of the 3 1/2' ' barrel. Maybe this has changed but you better check. I think a friend of mine ran into that with a mossberg combo.