Tiamat
I've seen the future...
For ammunition, whether or not it's still usable, the biggest factor will often come down to proper storage. IE, the ammo should be ideally stored in a proper climate-controlled bunker, depot etc. where the storage interior doesn't see too many temperature extremes, and also importantly is consistently DRY and kept away from the sunlight and weather effects. Fluctuating temperatures, high heat, moisture and sunlight are all bad for long term ammunition storage. This is why if you happen to store ammunition in your house, you should avoid storing said ammo in garages and attics, and instead opt for storage space or safes in the house proper where one would assume the climate and moisture is more consistently regulated.
Remember it's not just the explosive filler (when applicable) and the cartridge case or shell itself you should be concerned about. It's also the primers and propellant as well.
Remember it's not just the explosive filler (when applicable) and the cartridge case or shell itself you should be concerned about. It's also the primers and propellant as well.