Ammunition Storage: Cool, Dry, Sealed, and Good for Fifty Years

In a sealed can with a rubber gasket, a silica gel desiccant pack inside, in a cool, dry, dark spot with a steady temperature, off the floor, away from solvents, cleaning chemicals and anything with ammonia, and locked. Label the can with caliber and date, use the oldest first, and open each can twice a year to check the desiccant and look at the rounds. That is the whole method; everything else on this page is why.

Decades. Smokeless powder is stable for 50 years or more when it is kept cool and dry, primers likewise, and brass does not age. People shoot 1950s surplus every day. What ends a round's life is corrosion from moisture, heat cycling that breaks down powder, or physical damage. Stored in a sealed can with a desiccant in a closet, the ammunition you buy today will work for your grandchildren.

Metal, for long-term storage: a surplus or new .50 cal can has the best gasket, stacks, survives being dropped, and keeps heat swings out. Its one weakness is rust on the outside in a damp basement; a coat of paint and a pallet fixes that. Plastic cans are lighter, never rust, and are fine indoors in a closet, but they warp in heat and under a heavy stack, and the latches and gaskets are not as good. I use metal for the deep stock and plastic for the range and vehicle cans.

It is worth it, and it is not mandatory. The box carries the lot number and the load data, which matters if a lot is recalled or a box starts misfiring, and boxed rounds do not rattle or scratch. Loose rounds in a can with a desiccant store just as safely and pack far denser. I do both: boxed for the calibers I keep long-term, loose in cans for range and practice stock. If you go loose, write the lot number from the box on a card and drop it in the can.

Yes. The can keeps humid air out; the desiccant deals with the humid air you sealed in on the day you closed it and any that creeps past the gasket over the years. A 40 to 50 gram silica gel pack per .50 cal can is plenty. Indicating beads turn color when they are saturated; dry them in a low oven and they go back to work. Check them when you inspect, twice a year.

Moisture corrodes brass and primers: green or white crust, and eventually a round that will not chamber or fire. Heat breaks down smokeless powder and can raise pressures; a car in summer, an attic or a spot next to a furnace does it in a few seasons. Repeated hot and cold cycles condense water inside an unsealed can. Solvent, ammonia and cleaning fumes attack brass. And ammo that is loose, unlabeled and unlocked is a safety problem before it is a storage problem.

A vehicle, no, beyond what you carry for the day. A closed car reaches 140 to 170°F in summer sun, which is above the 150°F ceiling for smokeless powder, and it swings 80 degrees a day; ammunition left in a truck for a year is the most common ruined ammo I see. An unheated garage is borderline: fine in a dry climate in sealed metal cans on a shelf, bad in a humid one or anywhere it freezes and thaws daily. A closet inside the house is right.

Look at it. Clean brass or a light, even tarnish is fine. Green or white corrosion, especially around the primer or the case mouth, a split neck, a dented or bulged case, a bullet pushed back into the case, or a primer that is raised, dented or crusted, and that round is scrap. If it looks good, it almost certainly shoots. Fire a few from an old lot at the range before you trust the batch; a click instead of a bang, a weak report or a stuck case means the lot is done. Never shoot a round that looks wrong to see if it works.