test1328,
I have tested a bunch if different bullets in a pair of .264's, one an original M70 Westerner with a 26" 1-9 twist barrel, and the other a recent Ruger Hawkeye with a 24" 1-8 twist barrel. Had zero problems getting any bullet (including 140 Berger VLD's) to stabilize here in southwestern Montana at around 4000 feet above sea level. Had the same experience with a 1-9 twist 6.5-06 I had for a while around a decade ago, where the 140 VLD was the most accurate bullet.
I doubt you'd have any difficulties in Colorado.
