I bought one of those "Food Saver" vacuum machines a while back. I throw however many boxes of cartridges into a bag, seal it, and date it. Bulk, unboxed ammo is more difficult. My loose .223 bullet points pierced the plastic bags as they went under vacuum pressure. Pre-wrapping in rags, heavy paper, or spare boxes should fix this. This process is obviously moisture-proof and theoretically shouldn't need silica gel or other media that might need ocacsional maintenance. Very handy for storing in my basement, which is extremeley cool, but runs about 70% humidity. I haven't stored ammo this way long enough to report on long-term effectiveness, but did test the bags with various foods, refrigerated and not. Their manual doesn't lie‹foods keep about 3-5 times longer when sealed with this thing. I assume ammo will enjoy greater benefits. Costco has Food Saver machines and the replacement bags for them (which are very expensive). Much cheaper than Cabela's and other places I've seen them. Anyone else tried this over a long storage period? Six months for mine and the seals are still good.