Have you looked at the ones from Ballistic Products?

http://www.ballisticproducts.com/Dispersor-Spreader-Wads/products/743/


I used to make spreaders by adding a couple of overshot wads in the column or thin cardboard X's similar to the X-Stream from BP. They seemed to work, but I never did a scientific test. frown


'Four legs good, two legs baaaad."
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"Jimmy, some of it's magic,
Some of it's tragic,
But I had a good life all the way."
(Jimmy Buffett)

SotG