My friend shoots Fiocchi pheasant load 6's in his Beretta 391 (26" barrel) and it throws a good 40 yard pattern. Best lead 20 pattern I've seen. He's had some extensive neck problems and surgeries.
I watched him smack one at 38 yards with it this past spring.
Oh ye, he uses a Carlson choke but I don't know the diameter.
EDIT: He uses the lighter loads due to his neck issues. I spoke to him and he uses a Jellyhead choke, not a Carlsons. Forgot to ask the diameter. If we pattern together for this spring I'll post pics.