[RMcL]

SHR970 "Depends on the state you are in. Some states tell you which sizes are legal."

I have seen regulations like that: "00 Buckshot or larger"

Then 00B as loaded in this 20 gauge ammo from Rio Ammo would be legal:

http://www.rioammo.com/law_enforceme..._buckshot.html

http://www.shooterspagetx.com/rio/game_buckshot.htm

http://www.ammunitiontogo.com/produc...gauge-buckshot