To combat humidity and compensation there are dehumidifiers on the market to solve this problem and prevent surface rust of firearms from occurring. Never store your firearms in cloth or leather gun cases or even leather holsters. Moisture can be retained and create an environment that invites rusting.
There is an electric dehumidifier by Browning [see Amazon advertisement below] which works quite well, about a foot long to be hung vertically at the front of one of the walls of your gun safe. The heat will prevent condensation and only uses about 18 watts of power or less. The best model is with tubes that are 1/2” in diameter.
In a safe room, a small fan installed with keep air circulating and helps to prevent condensation.
When you are out hunting, protect your firearm stock with Carnuba wax, wiped thinly over metal parts as well as the rubbed into the stock. Cleaning and lubricating your firearm with Break-Free CLR is also a plus. When I was jungle training in Panama, the arms room had no windows or circulation; so we coated Break-Free heavily on our M16s and by morning there was a film of rust formed under the coating of oil! However, wiping our firearms of all that extra oil removed the rust because it was prevented from adhering by the Break-Free. Expensive in comparison to other firearm oils, it is by far the best – used by US armed forces since it came out in the middle 1980s. It replaced the WW2 gun oil that was used until that time.
So, whenever you return from the range or out in the field, always take time to wipe your firearms with Break Free. Your firearms will be happier.
If you must store your firearm for long periods, the American Gunsmith Institute suggests to use Vacuum Food Storage Bags (sealed) after giving it a wipe of Break Free. A test revealed that compared to putting a firearm in a waterproof container, the vacuum sealed plastic prevented corrosion by 100%.
Firearm owners and collectors usually spend a good deal of money on their firearms – so take care of them!