I did an article for Whitetail Times on buckshot guns a few years ago. Actually found some of the patterns and the article in my email.

This is a pattern at 40 yards with a Beretta 390 Silver Mallard, Briley modified choke, Winchester supreme 3" 00 buck 15 pellet load. 3", 10", 20" and 30" circle.

Needless to say, the gun was a killer. My wife killed her bear with it a few years ago before I bought her a Browning Silver Micro Midas 12ga (she is short). Great shooting gun that Beretta was, but I could never shoot it as well as my Remingtons.