About 12 years ago when I got into duck hunting I didn't have a shotgun with screw in chokes, and I didn't want to shoot steel through a full choke so I had the barrel threaded on my 12 ga. 870. With the imp. cyl. it shoots steel like a full choke, I've easily finished off ducks that hit the water at 50 yards. Now here's the question, is there a difference with these newer guns? My girl is getting a youth model 870 20 ga. for christmas, I have the full, mod. and imp. cyl. chokes for it. She wants to go duck hunting, wich choke should I use in it to shoot steel shot?