Most accurate semiauto's using the .308 or 7.62 NATO round are either M1's rebarreled or M14NM's rebarreled, both with aftermarket custom match barrels by Obermeyer or Kreiger. Those built by that handful of 'smiths catering to the top military team shooters would shoot all day long with good commercial match ammo inside 4 inches at 600 yards.
I know of no other semiauto rifle for this cartridge that's ever been able to do that. Note that one that shoots 2/3 MOA at 100 yards won't come close to 2/3 MOA at 600. They'll need to shoot almost 1/4 MOA at 100 to do that well.