I live in the southern Appalachians and it's very moist here. (It rained last weekend for 3 days, and it's raining again this morning.) Even though the home is new construction with poured concrete walls, I run a dehumidifier in the basement all year long. Everyone I know does this; it's just part of living in the South. You either have a dehumidifier, or you have mold on the joists and sills. So the basement is kept at 60% RH.
I also oil everything that moves. Especially guns. If it doesn't move but needs protection (like reloading dies) then they get sprayed with resizing lubricant, such as Hornady
One Shot or Dillon
Case Lube which have a
high wax content.