RC20,
At Gunsite they warned us as little as one summer in the trunk of a police car that stayed parked outdoors most of the time could kill primers so they didn't fire. The military
intentionally heats powder to 140°F to accelerate break-down to study the effect of stabilizers. Heat and shooting supplies are a recipe for encouraging future duds.
If you want to dry and store primers, get some freezer bags and a sealer and pack them in there with a desiccant pack. The mil spec ones are a smectite mineral clay like bentonite or montmorillonite and are available in tubs,
like these. Also, the
Moltan oil absorbent granules sold at AutoZone are pure montmorillonite clay, and you can spread them out on a cookie sheet and heat them in an electric oven at 250°F or higher to drive the water out. You are finished when they stop losing weight. Drop them into a cloth bag and pack them in the sealed bag with the primers.