[bigalshootmupper]

I can't say for certain, but I would attest that it is the fluctuation of temperature and the moisture level that will damage your ammo. If in a controlled environment, I'd say 100 years may be max. I know from electronics testing, 140F is exponentially harsher than 70F. If at 70F, 100 years and I'd bet it is fine. I am currently shooting 1953 Bulgarian 7.62x25mm ammo that is very consistently shooting 1880 fps on my chronograph out of my 1952 Polish Tokarev. It was stored in a sealed, or looks to be soldered, air tight container.

I keep my ammo inside the house, stored in a wooden cabinet with a quart sized can of desiccant to absorb moisture. I'd say vacuum packed is better.