87 V-Max.
The 85 grain Sierra is a good bullet but B.C. sucks and if you're wanting to stretch it to more than a quarter you will end up with a rainbow like trajectory.
If twist allows one of the heavy 103+ grain bullets may be a good choice.
I don't shoot long distances, but in the accuracy department I never had a VMax bullet out perform the 85 grain Sierra in the 243. Maybe it's just been my limited experience.
