Getting a CONSISTENT 1/2 moa out of a bolt rifle takes a bit of work. I doubt you'll find a factory 308 semi that'll pull it off. Maybe there are some semi-custom jobs from the 'custom shops' or botique manufacturers that'll do it, but those aren't really 'out of the box' guns. An AR-10 would be a good starting platform,and it might even be able to produce the odd 1/2 MOA group if you get a good one. But to be able to shoot into 3" at 600 yards, shot after shot, consistently - you'll need some custom work. In any case, bring the VISA