Good question, I've got several cans of spam ammo that's never been opened and it depends on who you ask as to how long it will last. I've got 7.62X51 lake city ammo left over from Vietnam hanging in the gun store with corroded primers. I would like to hear other peoples opinion on this though.Just for the record, Lake City FMJ is not my first choice for ammo.
PS Every time I go through Macon on my way to Florida I see a lot of Zombies. Up here in north Georgia we just call them Democrats on the half shell.