Blasers. That is what I get from the Glock boys when I attend them.
No reloads, they won't let you shoot them, because you shouldn't shoot them in Glocks.
I have seen a lot of UMC at the matches too.
I'm sure that a few of the unlimited class guys are using some "perfect" load, but most of the poeple at GSSF matches are just having a good time with their Glocks and getting a good competition experience while hanging around with other Glockatisti.