Doverham,
Another option from Ballistic Products is the PISK (Piston Skeet) wad. It's not a spreader but it does move some of the shot from the center of the pattern to the periphery thus increasing the effectiveness of the pattern at close to moderate ranges.
I've loaded a lot of these in AA & STS hulls using 1oz & Clays or 700X as per the BP manual. They do seem to help with tightly choked guns for sporting clays & they don't add any steps to the loading process which is important to me for volume loading. I have no data in any of my manuals for American Select with this wad.
As previously mentioned you won't know w/o patterning & the distribution of shot within the pattern at a given yardage needs to be considered just as much as pattern percentage.
