Taking a gun inside and outside usually a condensation problem. I hunt in NW WI and had below 0 temps and have learned the hard way that you always leave the gun outdoors. As I have had condensation freeze up the action of a 742 Remington and could not cycle it to load easily then it did not fire when needed. Others I have hunted with have had this happen with bolt actions as well. If you use black powder bringing the gun inside will render your charge useless from the condensation dampening it. So you either leave the gun outside or fire it at the end of the day and bring it inside and fully clean it and reload after it acclimates to the cold the next morning. Or do as I do keep muzzle taped off or covered with condom to keep moisture out and un prime and put plastic wrap over nipple to seal off powder. In the morning you can remove plastic wrap and put a primer on and your are good to go. You can safely shoot thru tape or condom as it is blown off by the column of air ahead of the bullet and does not affect accuracy. I have done this procedure for the full MN black powder season 3 full weekends and the rifle still fired to unload on the last afternoon. The tape or condom also keep debris and moisture out of your modern guns as well and has worked for me for over 30 years.
Mwal
Mwal