I don't own a 28 gauge and can not be much help to the OP but for some of the side bar... RST sells a number of 28 gauge loads, will do mix and match sizes when you call and order a case and they DO sell the Nice Shot in the 28, but not in waterfall size shot unless you are comfortable shooting ducks and geese with #6... I have no experience in these matters but would believe someone if they said they used #6 over decoys.
The 2 3/4 #6 and #7 1/2 copper plated for $15 a box seems like where I would go if I was in your boat... $150 for a flat... don't shoot trap with the gun and imagine how long 10 boxes would last just hunting... several seasons I would imagine...
