Have not shot yet. I have some 440gr Ultramax that are advertised at 1350fps. I'm going to try to get to the range next weekend. I'm going to get the RCBS 360gr mold and load up some plinkers and increase the recoil level gradually.
I like the looks of the Lee 440gr, and the article about the gun and it's development has some great info on how to duplicate his custom molds. Read the article at the link, it also talks about how a friend of his put 50 consecutive shots into a 55gal drum at 700yds.
I don't have much experience with full house loads of this size, and I want to cut my teeth on something a little softer before I go to the really big boomers. The guy who put this out is launching 720gr @ 1250fps.
WOW.
I know a lot of folks will say that there is no need for something this big, and that can be debated somewhere else. I just really enjoy S&W and look forward to exploring just how far this sucker will go...preferably without putting a divot in my head.