I have just watched many geese fall to BC. 2 wks with friends from US 2 3/4 #4 made some great kills. #2 3 & 3 1/2 were used by most. Over decoys the 2 3/4 were great. I have never shot BC, but they hit hard, I believe the long tight wad/shot tube is the reason. Your 20 will shoot them IMHO. Over decoys you will have enough power to take any honker.