Thank you for your answers... It makes sense that gun powder produces its own oxygen... otherwise you could not shoot a firearm underwater...

I was asking because it seems like a sure way to protect ammo from the degradation. I guess it might be overkill since we see 50 year old ammo that still fires..

I'm not sure if I'd trust defensive ammo that was vacuum sealed "just in case" there was some issue.. but from what was said here.. that should not be a problem...