Well, bought some #4 3inchand went out with the 20g. With a full choke, using JW's target (bucksnort with the target circles on it) i was only getting 5-8 pellets in the prescribed kill zone(vertebrae and skull)at 30 yards.
The pattern was very wide in my opinion. Approximately 22 inches in diameter.

Would getting an extra full choke and going with #5 (i'm assuming more pellets), generally produce better results.

FYI,
This is the first time i'm trying to pattern a shot gun so i may be way off base in my thinking here. I can dial in a centerfire rifle and understand that just fine but obviously this is a different animal all together