Bullets are much more easily stabilized in thin, dry air, as typically found at higher elevations in the West. In thicker, wetter air (like that on the seacoast of Alaska), they're more diffcult to stabilize. A spinning bullet starts out of the muzzle with the point wildly gyrating, then "goes to sleep" within a certain distance, with the point forward. Extra air resistance, caused by denser, damper or even colder air, keeps the bullet from going to sleep as quickly, and in extreme cases may even prevent it from completely stabilizing.
<br>
<br>This effect is well-known among target shooters, but not among hunters because most (not all) factory hunting rifles have twists faster than required for most bullets. The main point is that if you use a slower twist that theoretically barely stabilizes a certain bullet, it may not stabilize under certain atmospheric conditions. Which is yet another reason to choose a slightly "fast" twist in any custom barrel.
