What's the best way to store ammo? I got some in ammo cans with desiccant bags and some vacuum sealed. Do you think they'll be fine 2-3 yrs from now? Got some 223, 9mm, and a bunch of 22.
For long term storage (like 10+ years) ...
#1 consideration is moisture. Use metal (surplus or new) metal ammo cans, or sturdy plastic ammo containers. As long as they have good seals to keep out humidity and water, they should work fine.
Use desiccant to absorb moisture inside the can. if they are reusable, make sure to reactivate them periodically. if they are disposable, replace them periodically.
Wear latex gloves when packing ammo. Depending on your body chemistry, the oils on your skin can cause severe ammo corrosion.
Put a moisture/humidity gauge in the area where the ammo is stored. Have it alert you when the humidity exceeds a safe level if it has that feature. Here on Oahu, I have one in my safe. It exceeds 50% humidity if I don't change the DampRid product monthly. i get an alert at 68%. The recommended level for ammo I've seen is max 25%. That's not happening for me unless I get a central AC home with a dehumidifier.
Move bulk ammo from cardboard containers to plastic bags, like Ziploc. Cardboard can retain moisture.
Keep ammo cans off the floor -- either on shelves or a pallet.
If there's a chance the cans can get wet (pallet on the basement floor next to a water heater and beneath water pipes?), cover it well with plastic sheeting or tarps.
#2 consideration is heat. Below 150° F is safe. if locked in a shipping container in the desert or locked in the car under Hawaii sun for 3 months, it might be a good idea to start rotating that ammo for range use. I doubt this temperature concern is much of one.
For short term storage, I would advise using many of the same tips above to keep the ammo "fresh". I actually make one set of long term storage cans, usually larger 50 cal, and smaller 30 cal cans for range use. Keeps the lids closed on the storage cans and keeps the weight down for range visits.
Periodically, you will take from the long term can to replenish the range supply, but cracking open those cans shouldn't happen nearly as often as the range supply. I assume that helps prevent moisture from getting into the long term storage.