Maybe you’re buying bulk ammo because you found a great deal. Maybe you came across an old case of ammo in your aunt’s attic. Or maybe you’re stockpiling for the zombie apocalypse. In any of these scenarios, there are two questions you will probably ask at some point:

1. How long does ammo last?
2. How can you tell if it’s gone bad?

These are both reasonable questions. Ammo isn’t exactly cheap, so you don’t want any rounds to go to waste. Plus, firing expired rounds can potentially damage your firearms or yourself.

Storage conditions, round types, and component quality all play a role in ammo shelf life. But don’t panic and throw away all your old ammo just yet. In this article, we’ll dive deeper into the subject of ammo shelf life to help you gain a more thorough understanding, exploring optimal ammo storage, guidelines for ammo shelf life, signs of bad ammo, and some tips on ammo management.

Let’s take a closer look at how long ammo really lasts.

General Ammo Shelf Life: The Short Answer

Most modern centerfire ammo is guaranteed to last at least 10 years. But in fact, it can last several decades if stored under optimal conditions.

If you’re shooting your guns regularly, shelf life shouldn’t be much of an issue (unless you’re buying pallets of shotgun shells or 55 gallon drums of 9mm). That said, it’s still best to store ammo properly if you’re going to store it for any length of time.

How to Store Ammo

The quality of ammo storage is the primary controllable factor that determines ammo longevity. Even though modern ammo is designed for the rigors and elements of the outdoors, it’s best to take a few precautions to optimize your storage options. This way, you will get the most out of your ammo and make sure it lasts as long as possible.

For effective long-term storage, focus on optimizing the following factors:

Moisture

Moisture is the key driver of ammo degradation. Moisture can deactivate the powder and primer, rust the metal casing, and degrade the lead bullet. This doesn't have to be from direct water contact or submersion — high humidity can be enough to cause the same effects over time.

That said, most modern ammo is water resistant and will continue to function even after being submerged in water for short periods. While the shelf life will be reduced, some rounds affected by water may still fire like normal.

Storage Tip: Keep ammo in the dryest possible place. Use desiccant packets to absorb moisture from the air (those little “do not eat” packets found in packaged foods).

Temperature

Avoid storing ammo in high heat (above 150 degrees Fahrenheit). This can damage the propellant, reduce the effectiveness of the round, or deactivate it altogether. Temperatures over 400 degrees Fahrenheit (e.g. an oven) can cause rounds to pop off. Moral of the story: Don’t put ammo in the oven!

While cool temperatures are ideal, it’s just as important to avoid temperature variance. Like a cold glass on a hot day, temperature discrepancies lead to water condensation and moisture accumulation (which is a problem, as described above).

Storage Tip: Keep ammo in a cool place with minimal temperature fluctuations.

UV Light

UV radiation (sunlight) also degrades ammo components over time, so it’s important to keep ammo away from windows or other areas that receive direct sunlight.

Storage Tip: Keep ammo in the dark. A safe is ideal for this, and it also adds an additional layer of security.

Oxygen & Air

Oxygen rusts and corrodes metal, so it’s important to minimize air exposure for your ammo. This is particularly important in coastal areas with salty air that can wreak havoc on metals.

Storage Tip: Keep your ammo in an airtight container (such as a military-style ammo box) or use a vacuum sealer.

Orientation

Ammo positioned incorrectly can deform. While ammo is both durable and expendable, it’s also a precision instrument. This is one of those factors that doesn’t matter in the short term but can cause a problem over a long enough time period.

Storage Tip: Always store your ammo with the bullet pointing up.

Movement

Excessive shaking and rattling (i.e. driving around with a trunk full of ammo) can cause deformities and damage over time. This is caused by both the general movement and the rounds knocking against each other.

Storage Tip: Don’t store rounds anywhere they could be shaken easily, including in your car, on your washing machine, on your speakers, etc.

Chemicals

Avoid exposing your ammo to lubricants, solvents, and other chemicals, as these can degrade ammo. Note that it’s impossible to avoid this once a round has been loaded into a magazine. That’s why those rounds should never be returned to your long-term storage area after being loaded once.

Storage Tip: Store all chemicals – including those used for maintaining your firearms – away from your ammo.

Organization

As ammo shelf life is measured in decades, it might be easy to lose track of the status of your rounds. To ensure optimal storage, track how long you’ve had your rounds and what conditions they’ve been subjected to.

Storage Tip: Keep a log in your ammo box so you always know the status of your stored ammo.

Fire

This should go without saying, but exposing rounds to fire can cause them to pop off or explode. If for some reason you didn’t know this fact, we recommend you stop what you’re doing and seek out expert instruction on how firearms work.

Storage Tip: Keep your ammo away from fire! Don’t store it near a fireplace or any gas appliances.

What Is the Ideal Storage Solution?

While these tips are important for optimal storage, don’t get too hung up on the details. You don’t need a gyroscopically-balanced storage case to drive to the range or a hermetically-sealed titanium vault to keep your rounds stable.

With that said, we recommend keeping your ammo somewhere cool, dark, dry, secure, and stable. In most houses, this is going to be a closet. Avoid attics, basements, tool sheds, or garages unless they are climate-controlled (though this may not be as much of a factor depending on where you live).

Within the closet, keep your rounds together and organized in an airtight container. Depending on how many rounds you’re storing, this could be a single ammo box, several boxes for different types, or an entire vault.

For security (and if you have children), consider keeping your ammo on a high shelf, using a securely locked box or vault, or putting a lock on the door to where you’re storing the ammunition. Remember, this is going to be long-term storage. You want to focus on optimal conditions and security over rapid accessibility.

How Long Does Ammo Last? (Hint: It’s Not Forever)

If stored properly, ammo can last decades.

As an analogy, consider a loaf of bread. All bread is sold with a “best by” date stamped on it, but several factors determine its actual shelf life. Bread stored in a freezer will last longer than bread stored on your back porch. Bread quality, type, and ingredients also play a role.

Bread also doesn’t just instantly transform from edible to a moldy green mess. It’s a gradual process where the bread slowly becomes less edible over time. Ammo works in a similar way. While it technically has an expiration date, storage conditions, component quality, and ammo type directly affect longevity. Like bread, ammo doesn’t just suddenly go bad — it degrades slowly over time.

Storage Conditions

Anything less than optimal storage conditions will speed up ammo degradation. Moisture, heat, temperature fluctuations, oxygen, UV radiation, chemicals, lubricants, and improper storage orientation will all speed up the decay of your ammo.

Ammo Quality

Higher-quality ammo degrades more slowly. Of course, the tradeoff is a higher price. This becomes a moot point if you shoot a lot. While high-quality ammo has additional benefits, paying more for ammo longevity and then going out and shooting it every week kind of defeats the purpose.

With that said, if you’re creating a gun collection for the end of the world, you might want to buy the highest quality ammo you can afford. Assuming proper storage conditions, it will last the longest.

Ammo Type

Finally, ammo type also plays a role in how long ammo lasts. In general, steel materials rust more quickly than brass, and exposed lead bullets (hollow point) degrade faster than bullets enclosed in metal (full metal jacket).

Gunpowder also degrades over time, though modern smokeless powder degrades much slower than vintage black powder ammo.

Centerfire rounds have a shelf life of 10 to 20 years or more, while rimfire rounds retain effectiveness for just one to two years. Shotgun rounds last the longest, and will remain effective for many decades with proper storage.

How To Tell If Ammo Has Gone Bad

Sometimes it’s obvious. If you find it buried in the backyard or submerged in a bucket of water, don’t bother — it’s not worth the risk of damaging your gun or yourself.

Sometimes, however, it isn’t so obvious. Here are some factors to consider to determine if your ammo has gone bad:

What’s The Expiration Date?

Ammo expiration dates are mostly for liability protection and sales. It doesn’t help a manufacturer’s bottom line to tell you their ammo can last almost forever under the right conditions (you probably wouldn’t buy as much after learning that). However, it gives us a starting point to determine what we’re dealing with.

If you come across ammo that isn’t in a box and you have no other information about it (e.g. you found a bag of bullets in a dumpster), you’re better off just disposing of it.

Do the Rounds Look Right?

First, visually examine the rounds. Look for rust or other corrosion on the casing and bullet. If the lead is partially exposed, check for signs of degradation.

Try to see if the rounds are discolored. Of course, this is difficult to notice if all the rounds are similarly affected, but try to compare the rounds with each other to identify disparities. You can also compare the rounds with a new box of the same brand.

Finally, look at the box itself. Besides general aging, does it look damaged or mangled? Does it look like it’s been wet recently? Is the bullet torn or punctured? Any of these signs could indicate the rounds have been roughed up. If the box is trashed, the rounds probably are too.

Do the Rounds Feel Right?

Next, examine the rounds by touch. Do you feel any dents, divots, swelling, or general alteration? Do you feel dampness on the box or the rounds? These signs might indicate that the rounds were damaged or that some chemical reaction inside the round is causing it to swell without being fired.

Do the Rounds Sound Right?

Once the rounds pass the look and feel test, you might decide you want to test fire the rounds. Proceed with caution!

Do you notice any sound discrepancies when the round is fired? One thing that could cause an unusual report is if the round is coming apart inside the barrel (wadding), thus depositing debris inside the gun.

Do you hear a click instead of a bang? This is a misfire and indicates the bullet is a dud. Did you pull the trigger and notice a delay before the bullet was fired? This is a hangfire. While it could indicate a problem with the gun itself, it’s most likely a sign of a faulty bullet primer.

All of these situations are potentially dangerous! If you hear anything other than a clean, immediate bang after you pull the trigger, you need to clear and clean the gun. The ammo is likely bad, and you’re risking both your gun and your health if you keep firing it.

Ammo Management Tips

Rounding out our discussion on ammo longevity, here are a few tips on managing your stockpile to ensure you’re getting the most out of your ammo:

Use Oldest Rounds First

To keep your ammo stockpile fresh, shoot your oldest rounds first. This way, your supplies are constantly being renewed and shelf life never becomes an issue.

This is particularly true for any ammo you carry in the field. Rounds that have been loaded into magazines, exposed to the elements, or those that have generally undergone any wear and tear should no longer be considered “fresh” and should not be returned and stored with other ammo. Next time you go out to shoot, shoot these rounds first.

Remember Murphy’s Law

Whatever can go wrong will go wrong, at the worst possible time. This is an important law for anything related to firearms and applies to ammo as well. Don’t risk your tools or your health for questionable ammo (either in training or for self-defense).

Ammo is expensive, but it’s not expensive enough that you should be training with or carrying questionable ammo. When in doubt, throw it out.

Don’t Obsess Over the Details

At the same time, don’t forget that modern ammo is highly advanced, durable, and effective — even the cheaper brands.

While the guidelines suggested here are for optimal results, we’re still talking about timelines of months, years, and decades before ammo becomes unusable. The idea is not “keep ammo like this or else it will instantly be useless.” It’s more like “if you’re going to keep ammo in longer-term storage, it’s best to do it like this.”

Everyday Carry (EDC) Guidelines

EDC is a unique situation, so there are a few guidelines you want to keep in mind for best results. We’re dealing with the highest possible stakes, so it’s critical you take every opportunity to mitigate the effects of Murphy’s law. Your life and the lives of your loved ones might depend on it.

When you carry ammo, you’re exposing it to the worst possible storage conditions. Every day, your ammo is exposed to moisture from your body and the environment, in addition to temperature fluctuations, solvents and lubricants in the magazine, oil from your fingers, and (since you probably carry hollow points for self-defense) the lead bullet is particularly exposed and vulnerable to damage. All of this adds up to a terrible ammo storage environment.

That’s okay — this is what ammo is designed for (to be loaded in magazines). However, to make sure you’re always carrying rounds you can trust, it’s best practice to replace your EDC ammo a few times per year and to never carry the same rounds for more than six months at a time.

Fortunately, this shouldn’t be problem if you’re following a well-designed training and maintenance schedule. If you’re carrying a gun in public, you need to be doing range training two times a month at a bare minimum. This is the perfect opportunity to fire through the rounds you’ve been carrying for the previous three months and replace them with new rounds. You can test your ammo, maintain your skill, and always make sure your rounds are fresh.

Ammo Disposal

If you think you have ammo that’s no longer safe to fire, don’t just throw it in the trash. It’s dangerous and explosive, but it can also cause lead to seep into the ground and pollute the water supply.

Be a good citizen and always dispose of defective rounds properly. To learn more about proper ammo disposal in your area, contact your local police department or gun store. If they can’t dispose of it, they’ll know who can.

Final Thoughts

With the right storage techniques, most high-quality modern ammo can last a long time. However, shooting regularly makes you a more responsible gun owner and naturally helps keep your ammo stock fresh and free of bad rounds. Do yourself a favor and get out to the range a few times per year, so you never need to worry about shelf life with the ammo you buy yourself.

However, if you do find yourself with some old ammo stored under questionable conditions, you’re better off disposing of it. Bad ammunition could potentially damage your gun or yourself. It’s just not worth the risk.

If you’re in the market for quality ammunition for your inventory, Pro Armory has what you need. Our veteran-operated store is fueled by a team of firearm enthusiasts available to help you choose the perfect round for your arsenal. We offer small boxes and bulk cases of several calibers and brands at the best possible prices — all in stock and ready to ship right to your door.

Keep your ammo stock fresh with new ammo from Pro Armory. Browse our online store today!