Thanks guys! Good info.
Rule3 - I did look at the Hodgdon site before starting this thread. I always go to the powder manufacturer first; however, I always want at least two published sources if at all possible. Also that data is using a magnum primer as you pointed out.
I broadened my search and Google found a post here that I didn't find (?)
Shows Winchester data from 2003 - post #9:
.357 Reloading data needed
That shows a maximum charge of 6.7 grains! It's also going 1,275 fps which is well over the limit for swaged lead bullets (somewhere between 950 and 1,100). Don't worry - I'm not going to try that load.
Looks like starting my ladder at 4.5 grains and working up is the way to go for now.
P.S. I don't know why I got better results
from this site using Google search than this forum's search.