You are way over thinking this my friend. Get your favorite source for recipes (lyman 5th,
http://www.hodgdon.com/ , ect.) and find a lead shot recipe that fits your hulls, powders, and wads. The only stipulation is that the load should have a pressure lower than 10,500 psi or preferably 10,000 psi or under.
From your posts I get the feeling that you seem to view nice shot more closely to steel than lead. You can load a 2 3/4" hull with 1 3/8oz #5 nice shot and have the ballistic equivalent to 1 1/8oz of #6 hard lead. I believe nice shot to be far superior to steel and that a 2 3/4" loading would be more than appropriate for decoying ducks. But then I am a crazy that has used 1 1/8oz 1556fps #6 steel for ducks over decoys. But if you want to a 1 1/4oz or more of nice shot be sure you are willing to incur the financial costs involved with it.
If you are hard set for published nice shot recipes here you go. Might try looking for stuff next time, it was on the page before this one.
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