ive got cans of ammo i know is at least 15 years old. its stored in a storage shacl that is not heated or ventilated. its sat through temps below zero in the winter and hot and humid in the summer. ive yet to have one round not fire other then a can of 38s i loaded with lee tumble lubed bullets where the heat cause the lube to contmite the powder. after some miss fires i pulled the bullets from a bunch of them an found contaminated powder clumped on the bullets. anymore i wont use tumble lubed bullets and if i was to it would have to be ammo i was going to shoot right up and not bet my familys lives on. its the main reason pc has been such a game changer.