My wife bought one of those vacuum sealers. works real well for freezing stuff. she has a friend that claims cooked meat will last 2-3 years in the freezer.If you know someone with a seal-a-meal, just light lube and vacuum seal. You can also buy silica gel packs, or fill with dry nitrogen.
i know it works very well on leftovers from the bbq grill. much better than anything else I have tried.
have not tried it on guns yet.
i know that some coin collectors have used it to protect coins.