Ammunition has an incredible shelf life; many types can rest on a shelf for decades upon decades and still be as good as the day they were bought. That is -- if the ammo is kept in a cool, dry place.
Moisture is one of the greatest enemies to hunters storing ammunition for the long term. It can degrade the powder and cause shells to corrode. In short, it can render perfectly good ammo useless.
So what tactics should hunters use to keep ammunition stored safely and free of moisture?
First off, hunters should choose the location they’re going to use to store their ammunition. Note that ammo does not hold up well to fluctuating temperatures, so one of the best places to store it would be a heated/cooled garage or workshop. These areas work great because they’re dry and the temperature is regulated. As an added bonus, these areas are safely away from the house; to ratchet up safety another notch, store ammo in a different location than firearms to limit accessibility for children, intruders, etc.
Next, hunters should choose a locking, fire-resistant cabinet with heavy-duty shelving in which they’ll store the ammo. Then seek out some ammo cans equipped with working rubber seals, which will keep moisture locked out. You can find ammo cans like this at Bass Pro Shops or through military surplus stores. For added moisture resistance, add silica gel packs or other desiccant to the ammo cans.
By following these steps, your ammo will be all set for safe keeping.
On one final note, you should always contact local disposal experts if your ammo has indeed gone bad. In many places local police departments will take and safely dispose of ammunition.