I've used BH209 in stainless Encore platform rifles since BH came out. I've fired two primers, fired to fouling shots, then loaded the rifle for up to two (2) weeks, in weather that could change from 50° and downpours, to the next day 25° and 6" of snow. Not a single time, never, notta, did I ever have a speck of rust inside any of my barrels. Taking a rifle inside and then outside can be a problem for many, especially using other propellants. Leave your case in the cold, then put the rifle in the case (after wiping down the rifle with an oiled rag), then put it into the case before taking it into the garage. The cold case will help protect the rifle and it will warm slowly. I know many shooters who foul and then leave their rifles loaded for up to two weeks, with no rust problems.

I will say this, do what you feel is right for yourself and your rifle.