The only factory ammo that I have are my .22s, and I keep them in the box they come in.
The rest of my ammo is reloads which I keep in plastic reloading boxes.
All are in my reloading room where I keep temps and humidity the same year round.
This should keep the ammo functional for many years.
NRA Chief Range Safety Officer
NRA Pistol Instructor
NRA Life Member
DNR Certified Firearms Safety Instructor 37 yrs