I recently worked up a load using Cast Performance 200gr hard cast gas check bullet. I was going to use Win296 or H110, both identical powders by what I've read, but ended up using 2400 as a couple of fairly knowledgable reloaders with more experience than myself advised it would give top velocity.
Anyway, I started out at about 12 grains and increased charges .5gr up to 14 grains where I just started experiencing sticky case extraction. Stopped there as it was the most accurate load of them all. The chronograph said it was slightly over 1200fps. I have heard of older (read hotter data) going as high as 15.5 gr of 2400 used in Blackhawks, but I stopped not wanting to push fate. The revolver these were shot out of is a GP100, 4" barrel. I probably would only try these hot loads in something not as strong as the GP100. I did roll about as heavy a crimp as I could get on these as they are max length for a 357 cylinder.