Generally I use Alliant 2400 to load 357 magnum but my dealer can't get it, all he gets is Alliant Power Pro™ 300-MPfor Magnum Pistol. It's the worse **** I've ever used. Next to no load date. Using Alliant's single recipe (no min, no max) it pretty much duplicates 2400. OK I can live with that.
It has the consistency of baby powder. And like baby powder it just "fluffs" all over the place. Tried it in my square D and what a mess. Ends up all over everything and sticks like super glue. Got between the shell plate and press surface and turned into some kind of tough plastic sheet. Had to dissasemble everything and scrubbed it using a brush and brake cleaner.
Tried it in my RCBS single stage press, not much better results. Wants to bridge in the powder dispenser, sticks to the loading pan and blows all over (even when in the brass).

Loaded half a pound, going to burn the other half.