I ran some LE Federal Tactical 2 3/4 00 & 000 Buck (that's 9 & 8 pellet) today.
I only got to shoot a half dozen of each.
The average was:
10yrds 4" spread
Nothing larger than 4.5" and nothing smaller than 3.5".
This was from a 20" rifle-sighted barrel on an 870. The choke was IC but has been Vang'd. This is also the gun with which I hunt clays.
I will try to get back up to the range and do some shots at 15 & 25 yards.