Picked up some Shooters World "Heavy Pistol" and loaded an array of .357 Magnum cartridges with different charges with 158gr Zero JSPs. I wanted something more flexible than H110, something that could safely be down-loaded a bit (unlike H110). Shot them in a GP100 tonight. The lower charges in the Shooters World manual were crap: dirty burning, smokey, not very accurate. Things got good as I got closer to the max. Got some especially good groups with 11.6 grains and the Shooters World max of 12.2 grains. No signs of over-pressure. I could hardly tell the primers apart. It was just slightly harder to decap the highest loads when I got home...only slightly. I think I'll probably just go with 12.2 grains and be done with it, since it seems to me like a very conservative "maximum load", but I'll have to try them in some other guns.