I agree, when we hunted wolf, Caribou and Muskox in winter in the NWT, it could be as much as -55F ambient. Guns were never brought into a heated house, tent or cabin. All heating them up did was create a ton of condensation. Same with ammo, it was left outside with the gun. The other thing you find out in those temps is dry graphite for lube is about the only thing that works, or shoot them completely dry. Equipment that can be made to work reliably in those temperatures will work anywhere else in the world.
WYO300RUM
What messes up powder and primers the worst is excess heat and high humidity. Temperatures above 90 degrees will make both deteriorate over time, as will too much moisture, especially in primers since they are not sealed. My buddy that lives in a highly humid area keeps his primers in a waterproof ammo can with desiccant.
Speaking of Blizzard Babies: