Here is a link to Winchester and Hodgon load data if that helps narrow it down:
http://data.hodgdon.com/cartridge_load.asp
They give data for Longshot, HS-6, Universal, 800-X, SR4756 and SR7625. I have not used any of those powders...are any of them comparable in any way to WST so I can use the data to calculate a starting load?
Or, could I use the load data for .40 with WST to estimate a starting load weight? 135gr .40 uses 5.5gr WST as a start load. Somehow if I could calculate for the difference in bullet mass (135gr vs 125gr), and account for any case volume difference, I could estimate a 357Sig low-end start weight.
Anyone?