[PEC-Memphis]

Greetings,
I treat this the same as you would food storage items, keep in a cool dry place. the best way I know is to place your ammo into a Mylar bag w/oxygen absorbers, something like this.; https://www.amazon.com/Dry-Packs-10...TF8&qid=1482754204&sr=8-3&keywords=Mylar+bags
I would toss a few of these in your vault as well; https://www.amazon.com/Dry-Packs-Mo...482754400&sr=8-1&keywords=anti-Moisture+packs
With the protection the vault itself will give you that should keep your guns & ammo for several years.

My vote for best answer.