You shoulda called yourself Diehard Wolfdog.
Do you notice any difference in accuracy in such cold? There would be no such thing as subsonic at those temps. Mind you, there is the 720 fps and 9 something as well. Not sure what sonic velocity would be at that cold. I'm just wondering whether the cold affects the ammo, not so much the sound barrier effects although that may play a role too. although, as long as the round is well above or well below it should effect accuracy.