1:9 twist. Can it hold up accuracy-wise to 600 yards?
Accuracy wise, they'll shoot tight. Wind wise, you'll get blown around a bit at 600 yards. That said, I'll say that I've seen great scores posted at 600 yards by super human wind dopers.
Army shot 69gr Federal Gold Medal Match at 200 and 300 yards for a long time, even after the 75 Hornady's were available (I think they eventually switched to 77 Sierras). When I asked them why, the reply was that the 69's shot tighter than the the heaviers available at the time...and that they could read wind.
I've shot 77's out of a 9 twist that were marginally stable. They grouped well, but the holes were a bit oblong. But I know good shooters that were choosing 9 twist barrels to shoot Sierra 80's because they were getting better accuracy at 600 yards than 8 and 7 twists. I'm never that lucky, so I don't do it.
