Look on the barrel of the guns near the reciever. The choke should be stamped on the barrel. You should at least have a full choke, and extra full wouldn't hurt. You might be able to order an extra barrel that has screw-in choke tubes. I think you were confused about the 3 1/4" shells. You can only get 2 3/4", 3", and 3 1/2" shells for a 12 ga. Go with the 3" if your gun will shoot them. Again look at whats stamped on the barrel to see if it will shoot 3" shells.