Originally Posted By kevthebassman:
You don't have to do your own experiment. Real black powder especially, and nitro-cellulose powders, last a long time.
Just this year a collector got killed by some civil war ordinance he dug up. A shrapnel shell exploded as he was working on it. Not something that was stored with care somewhere, this was a shell he dug up out of the clay.
Farmers in France are always digging up WWI ordinance, bomb squads have to come out and dispose of it. Not sure of any specific instances of them being killed, but I imagine it happens.
Some WWI and II ordnance has an almost indefinite shelf life as the explosive charges used were either short lived enough that within a decade or two they were
harmless, or they used cast explosives such as TNT that basically will last forever.
There is no real advantage and some minor disadvantage to vacuum sealing modern
propellants. The plasticizers and solvents used can be drawn out more quickly
under a vacuum. If the packaging develops leaks it can draw in moisture. The best
long term storage is actually sealed in oxygen-purged, slightly pressurized
containers. Dry nitrogen is the best purge agent.
Regardless, modern ammunition will last your lifetime, and your kid's lifetime
in unsealed containers if kept cool and dry.