Well, Fairbanks' UAF campus police had to discontinue using the Glock 9mm and 10mm; at 40 below farenheight, the thermal shock will shatter* them when fired.
*shatter was what the Anchorage daily news called it. Having looked at pictures, no, not shattered. Rendered unsafe due to barrel cracking and upper receiver cracked to the point of immanent failure.
At 40 below F., M16 practice at Ft Rich is slowed, but continues.
And while long-term, wind chill makes no difference to non-thermally-active items, it does have profound effects upon motors, and upon how fast something cools to ambient.
So, if you have an abient temp of -50, and wind chill of -80, it cools as if it were -80 out until it hits -50.
Engines have it worse; engines NEED heat to operate (too much or too little, and the don't run); wind chil affects heat lost by the engine, and thus is running stable temperature. If the RST can not be brought up to a nominally useful range, loading may result in engine failure.
Many in Fairbanks have a bra on their vehicles. It's not there for looks, but to reduce air intake from the front, and thus reduce both wind chill and engine cold air intake. Remember, the radiator is where it is to prewarm intake air and cool the engine by conduction to flowing ram air, making use of wind chill effect to maximize cooling. If you block the radiator's forward flow, the air intake draws air from the rest of the engine compartment; the extra degree makes little difference... but the lack of radiator cooling and direct ram conduction losses upon the engine do.
