cayugad

I unload my rifle every night now, but used to store them for days on end.

Get some finger cots at a pharmacy. They are small condom like objects that will stretch over the end of the muzzle and keep the moisture from getting down there.

When you have hunted all day, if it was in wet, damp, or humid weather I would suggest shooting the charge off and cleaning the rifle then starting the next day on a fresh charge. If you're determined not to do that, do not subject your rifle and charge to extreme temperatures. Put the loaded rifle some where it will not be bothered. Mark the rifle with a red cloth through the finger guard to warn others that the rifle has a charge in it. Leave it in as near the same temperatures as the outside where you hunt, like a shed or garage, away from all moisture. I like to put a cloth on the ground and then put the rifle muzzle end on the cloth. This way if any moisture does form it will move down the barrel away from the powder charge. Be sure and take the primer out of the breech plug, then lay a cloth over that area to collect any moisture that might try to form.

Something to keep in mind, certain powders ... no matter how careful you are will still draw moisture. If it draws enough moisture you might have problems the next day.