hikermor: The real early fairchild ones are better in my opinion than any of the successors..which often only function single shot. and nothing wrong with a 6mm, if you handload..if you don't, then there might be issues with the care and feeding of your 600.

I often take a montana 1999 in 300 win mag (anything other than bear), or a mauser 3000 in 375 H&H (bear, moose, elk)as my primary for most hunting I do, with one of those WWG co-pilots for brush hunting in the swamps(hog).

TheSock: 2 issues with that. 1) civilian ammunition availability, 2) civilian weapon availability. Look at the FN 5.7 mm history for information on that, or the H&K G11 4.73 mm.
It's a great idea, kind of the top prize for weapon developers, short of a hand held plsama gun, but even if it went through testing and trials at aberdeen, ft. benning, and eglin, it might never be manufactured. I assume you mean the AAI LSAT project and the follow on contract..I missed the SHOT show in vegas this year, they might have had something at their booth to play with and to shoot on press day.