Based on both simulation and some experimentation, I believe the highest speeds for the lowest pressures will be in the 4895 burn rate. H4895 and AR-COMP are the temp stable powders in that neighborhood. It's hard to tell which will be better, but my money is on AR-COMP.
Due to crimp grooves being in the wrong places, I've been using a Lee FCD on everything, and .50 AK cases for the softs. Seems to work OK.
