Tut:
I would (and have) loaded Spred-R loads in AA hulls using the standard low pressure loading data from the IMR manual. I load 1/8 ounce less shot than the load calls for and insert the Spred-R wad, which seems to still fill the hull completely and provide a good crimp. I've never had the loads pressure tested, but they start in the 4500-5500 PSI range in the manual before the substitution and the wad weighs a whole lot less than the 1/8 ounce of pellets I remove. Breaks clay birds with some authority on the skeet field (but then, doesn't almost anything?).
In the alternative, you might check with Ballistic Products and see if they have any data, as they sell the wads. You could also contact Poly-Wad, who makes the Spred-R wads, and ask them.
Rem
