I think SLR has the most and best options for free float hand guards that I can find.
I talked to a fellow at a gun show last month who built a PSA 308 and he had a LOT of problems running into road-blocks to finish it. It seems you have to use proprietary PSA parts for this and that.
Somebody ought to write a book on building AR10's and DPMS pattern 308's and make some kind of chart to splain it all.
All in all I like Aero Precision; even if you have to wait for stuff to get on the shelf and wait wait wait to talk to a rep on the phone. It seems like really quality stuff.