I am posting again on wood. The wood is less understood and often left unprotected.
FIRST: No oil, No grease and NO SILICON. Google silicon if you like. Or take my word for it. My mildew problem on the stock was due to grease and oil on the wood.
The 50% RH is due to the wood content of firearms. If your guns have no wood (synthetic) then 30% is fine.
The wood will benefit from waxing and renaissance is the gold standard. Waxing a new gun is a good idea to add a layer of protection over the finish. New finishes are pretty good, but; more is better IMHO. Wax is also excellent (best in fact) for metal so that is a big stroke of luck.
Do not apply wax over a dirty, human oil, or gun oily stock. Clean that all off first.