I agree with Jim, load em, and shoot em and see what you get.
EXAMPLE: I have a 6mmRem with a 10 twist, charts say 90 & 100 grain are ideal, and indeed, 100s, 90s, and 85HPBTs are all good to 600 yards. It gets 0.5" groups at 100yrds with 60 grain bullets, but the groups fall apart after 200. The 55 gr get 4100fps, with spectacular terminal results on prairie poodles, but accuracy is 1.0" at 100yards and your lucky to hit a bull in the butt with a banjo after that.