Good point by Tom. The Gamebore 'Traditional' shells
http://www.gamebore.com/game-loads.asp (available at Cabela's) have a 'fibre wad' with no plastic shot cup and the patterns I obtained were quite open in my .007/.014 choked 16g LC Smith. Might be a good choice to open up the M/F chokes OR the Polywad Spred-Rs http://www.polywad-shotgun-shells.com/spred-r-spreader-loads/