I have an old Model 12. 30" full choke. Okay, fine, but that was with paper hulls. With modern plastic, it's XXFull. Took me a while to be able to hit doves and quail, although at 40 or 50 yards it was easier.
Main thing, regardless of choke, is to find a load which patterns properly and then make sure of your sighting.
You're from BATFE? Come right in! I use all your fine products!