I store my long guns in the flannel sock type cases to avoid nicks and dings in and out of the storage cabinets, (I have Homak steel cabinets in a under the stairs in a flame/access resistant structure, with a steel security door to the closet). Handguns go into lightly padded cases with a canvas exterior.

I've never had rust problems storing guns this way over the last 20 years or so.