shibumiseeker
Grandmaster
Everyone keeps talking about keeping ammo dry. What would be considered wet? At least at this time I do not load so my question pertains more to factory ammo. I assume, as long as I make an effort to try that most probably will be good enough to shoot for a long time. Is there a way to know for sure?
Wet can be anywhere from slightly damp to sitting on the bottom of the ocean for a century.
When ammo is subject to thermal cycling in a high humidity environment it can pull moisture into the casing, albeit very slowly. This moisture can't escape easily and COULD reduce powder and primer sensitivity (water does not deactivate primers or powder, it just desensitizes it, dry it out and it'll still go bang most of the time).
But that's not really important. What is more important is that the metal can corrode when moisture can condense on it. Dissimilar metals create a galvanic response increasing corrosion and so while ammo can be stored for years under harsh conditions, it's best to keep it in as temperature stable an environment as possible, preferably a cool and dry one.