I've got a hunting cabin in the upper midwest that I'd like to store a single shot shotgun in just in case I ever needed it. I was thinking about coating the whole thing in Mobil 1 grease but I'm not sure what to put it in, a plastic bag would just trap moisture wouldn't it? The cabin's unheated and not air tight so along with sub zero temperatures I have to battle high humidity. Is there a way to do this fairly cheaply?