I want to prevent my stored pistols and rifles from rusting. Most of them dont get shot very often (some never) and only get pulled out of their cases once a year or so to get wiped down with oil. Ebay has bulk silicon dessicant packs that often find in shoe boxes and I'm wondering if dropping one of these in a rifle case, pistol case or a 50 cal box full of ammo would be good for preventing rust from humidity. Also how do you know when its time to replace? Can these be put into oven and recharged?