I have had my 4" Model 29 freeze up and the cylinder become inoperable after taking a tumble into the snow. Plus carrying it close to my body in a tanker rig, it made just enough of a difference that the metal was a slightly warmer temperature and it attracted moisture. I could cock the hammer back, but the cylinder would not rotate. I worked my way back to the truck and stuck it up on the dash, and let the defroster thaw it out while I continued my jackrabbit safari with a Glock 21 .45 acp, which ran flawlessly no matter how cold it was.
A few years back a number of us gathered at Ken Hackathorn's place for a cold weather shoot. I cannot remember exactly how cold it was but it was well below zero and it was a good observation of both how men and machines operate differently in temps around -20s or so. Proper lubrication of weapons is critical. People definitely slow down and have to think through processes such as reloading guns, putting guns back in holsters safely with numb hands, doing transition drills, etc.
When it comes to firearms, I use a very light layer of 0W-20 motor oil. This allows both handguns and rifles to work fine. It has been my experience, hunting in sub zero temps every year that the semi auto with loose tolerances, like a Glock (versus a 1911) is FAR more reliable than a revolver. A single bit of moisture from body perspiration will cause a revolver to freeze up when that migrates into the lockwork.
There is a very good reason why outfits like the Danish sled patrols use a Glock when operating in the arctic. They have conditions that are obviously rather harsh and chose equipment that would operate best in that environment. Many may not know it but they chose to use old 1917 Enfield 30-06 rifles as their primary rifle along with the Glock 10mms.
I have carried a Glock .45 with heavy loads for many years in the mountains and find it to be ideal for harsh environments. Plus I like the very lightweight to capacity ratio. That is hard to beat. Normally when I get an animal like an elk down, I will leave my rifle at the truck and just pack a handgun for subsequent trips back and forth, either using a pack frame or a game sled to transport the meat out.