|How long does conventional ammo stay "fresh"? I have a stockpile of aging 12 gauge and 9mm, mix of types and brands-no reloads. Some of it might be as old as ten years, a lot of it is 5 years. Some has been stored in military surplus ammo cans, some in the original (cardboard) boxes. Do I fire it all off at tin cans and replace now or is it still reliable?