We tried 90-grainers at the USAMU for 1,000-yard competition. Couldn't get them fast enough out of a 1-6.5 twist 20-inch M16 to make much difference against a Sierra 80.
Push that 90 out of a 24- to 28-inch bolt gun and you get some impressive performance -- plus, 77s and 80s seem to like 6.5 twist just as well.