Does Ammo Go Bad? Do Bullets Expire?

Short Answer: Ammo does not really expire. There is no true expiration date stamped on a box of cartridges, and properly stored ammunition can stay reliable for decades, often far longer. What actually ruins ammo is bad storage. Moisture, humidity, and extreme temperatures corrode the case and degrade the powder and primer over time. Keep your rounds cool, dry, and dark, and they will be ready to fire when you are.

Do Bullets Expire?

No, bullets do not expire the way food or medicine does. Ammunition has no active ingredient that breaks down on a set schedule, so there is no printed expiration date to watch. A better way to think about it is a “best if used by” window that depends entirely on storage conditions.

Most ammunition manufacturers suggest a shelf life of around ten years, but that figure is a conservative estimate for warranty purposes, not a hard limit. Shooters regularly fire military surplus ammo that is 50 years old or more and it works fine, because it was sealed and stored well. Modern ammo is built to last even longer, with sealed primers and better cases than the ammunition of decades past.

What Is the Shelf Life of Ammunition?

The shelf life of ammunition comes down to environmental factors, not age. The industry’s own standards body, SAAMI, does not publish a fixed expiration date at all. Its guidance is to store ammunition in a cool, dry place away from heat sources, which tells you that conditions, not the calendar, decide how long a round lasts. Store a box of cartridges in a climate-controlled closet and it can outlive the person who bought it. Leave the same box in a humid garage and it may fail in a few years.

Two things drive the lifespan of ammunition:

• Storage conditions. Humidity, extreme heat, and excess moisture are what damage rounds. Control the environment and you control how long the ammo lasts.
• Original quality. Sealed, modern ammunition from a reputable ammunition vendor holds up longer than cheap or old ammunition with unsealed primers.

Here is a quick reference for how long ammunition lasts under different conditions.

These are general guidelines. Every load and brand is different, so a visual inspection matters more than any number on a chart.

What Happens When You Shoot Old Ammo?

Most of the time, old ammo fires like normal. But older rounds that have been through moisture damage can behave in a few ways worth knowing about.

Fresh brass is bright and shiny. As rounds age and meet moisture, the brass fades to a dull color. At that stage it is still safe to shoot. If it goes further and green corrosion appears, the case is weakening, and firing a corroded round can let high pressure escape through the case wall.

The bigger danger is a squib. If the powder has lost potency, the round can fire weakly and lodge a bullet in the barrel. Firing the next round into that obstruction can destroy the barrel and injure the shooter. This is why any round showing corrosion on the case or primer should be pulled from your supply.

If a round shows corrosion, especially on the primer, do not fire it. Dispose of the bad ammunition safely instead.

How to Spot Bad Ammo

A quick visual inspection catches most problems before they reach the chamber. Set a round aside if you see any of the following:

• Green or white corrosion on the case or primer
• Deep dents, splits, or cracks in the case
• A primer that looks pierced, crushed, or backed out
• Heavy pitting or rust
• Bullets that wiggle loose in the case mouth

Dull or slightly tarnished brass alone is usually fine. It is the corrosion and physical damage that signal a round has gone bad.

Proper Ammunition Storage

Proper ammunition storage is the whole game. Get the environment right and your ammo stays good almost indefinitely. Three factors matter most.

Humidity and Moisture

Humidity is the top enemy. It can form inside the round and out, and it drives the chemical reaction that leads to oxidation and corrosion. Keep humidity levels low and use airtight containers with a moisture absorber inside.

Temperature

Temperature swings degrade primer and powder over time, and heat and cold cause the metal to expand and contract, which can loosen the seal between components. Aim to keep ammo at a steady room temperature and away from extreme temperatures.

Light and Security

Direct sunlight heats rounds and drives temperature cycling, so store ammo in a dark place. Keep it locked away from easy access as well, the same as you would a firearm.

Storage Tips

1. Hold a steady temperature, ideally between 55°F and 80°F.
2. Store ammo in a climate-controlled spot, not the garage.
3. Keep storage containers in a dry place and drop in a silica gel packet, replacing it regularly.
4. Leave rounds in their original box and place that box inside an ammo can or ammo box.
5. Store everything in a dark place to hold temperatures steady.

What to Avoid

• Extreme temperatures. Above 100°F or below 40°F can affect powder and primer, and hot-cold cycling loosens components.
• High humidity. The fastest path to corrosion and dead primers.
• Casual storage. Never leave ammo in a vehicle for more than a day, and never in an uncontrolled garage or outbuilding. Rodent urine on brass corrodes it fast.
• Direct sunlight. The heat swings damage even modern ammunition.

Berry’s Storage Solutions

The right storage container is the cheapest insurance you can buy for your ammo.

Ammo Cans

Berry’s Ammo Cans come in 20, 30, and 40 caliber sizes, and the Tri-Can holds multiple calibers in one unit. A rubber gasket seals each can against air exchange and moisture, and the stackable design saves space in a safe. Cans are the pick when you want to store larger amounts of ammo in the right conditions.

Ammo Boxes

Berry’s Ammo Boxes range from 10 rounds up to 100 and are sized by caliber, with options for shotgun shells too. They keep your rounds organized so you can see what you have at a glance, and they make transport to the shooting range simple. Even old ammunition stores better in a proper box than loose in a bag.

Round out your setup with a silica gel packet in each container, and browse Berry’s full lineup of bullets when you are ready to reload. Always follow your reloading manual and published load data, and check your local laws before you load.