How Long Does Ammo Last?

Whether you are a hunter, a gun enthusiast, a military member, or if you are just considering the possible future zombie apocalypse we all think about in the back of our minds, ammo is important.

But imagine the zombie apocalypse came, and… oh no! Your ammo has gone bad! How would you have known, ammo doesn’t have a best before date, it's not like a ham, or a cabbage right? 

Well, no, ammo is not like a ham or a cabbage, it's more like a tin of baked beans. It will last awhile, but it will go bad eventually, and it’ll go bad even faster if you keep it in an unsuitable location.

So, before you go buying a crate of ammo in preparation for a zombie apocalypse, or a long off hunting trip, let’s take the time to talk about how long ammo actually lasts, if different ammo has different lifespans, and how you should store it so that if zombies do come, your ammo is still good to go.

Lifespan of ammunition

The shelf life of ammo is largely dictated by the conditions in which you keep it. Many manufacturers will anticipate that their ammo will last for a bare minimum of a decade.

Although, it is not unheard of for ammo to last beyond a decade if it is stored correctly.

In fact, the military have plenty of ammo that is being used for decades after it was made. Part of this is because in the military, they have got correct storage down to an art form.

Do different types of ammo have different lifespans

You ask some good questions. Well, modern ammunition of all types is designed to outlast you. Yes, it’s true, your ammo is made to live longer than the person who bought it.

In the past, ammo was made with black powder that acted as a propellant for the shell. But now, ammo is often made with a smokeless powder that lives much longer.

However, it also depends on the casing, steel cased ammunition is much more vulnerable to corrosion than brass is, though steel can last extremely long if it is correctly stored and kept away from any potentially corrosive elements.

Some modern ammo will come sealed in order to protect it against corrosives or moisture. A previously opened package can be easily vacuum sealed if need be.

Full metal jackets and brass-lined ammo are not as vulnerable to lead degradation as hollow points are. That being said, as long as you keep your ammo away from any potential exposure to extreme conditions, modern ammo types, all types, should last you a lifetime.

How should you store ammo

There are a few factors you will want to consider before you store your ammo, tips on how to best store it to ensure that it does not go bad, and that it lasts a lifetime.

Avoid Moisture

Dry ammo, is happy ammo. Moisture is probably the biggest issue when it comes to ammunition storage. You want to store your ammo in water-tight storage cases or containers to keep any moisture out.

You can use ammo cans of course, some even store it in sealable food containers. But, you want to keep ammo out of the rain, similarly you want to keep ammo away from humid conditions too.

Excessive humidity can lead to your powder failing. For this reason you should avoid storing ammo in a damp place, such as a basement, or in some cases an attic.

If you live in a high humidity climate, it can be useful to get a dehumidifier, as not only will it have benefits for your ammo, but also your whole house.

Heat is Not Always Good

High heat can accelerate the deterioration of your ammunition, so it is highly advisable that you keep ammo in a cool location. As an example, you do not want to be storing your ammo in the trunk of your car during a hot summer.

In comparison to this, you should also avoid storing ammo in a garage, not only due to safety reasons but also because some garages, especially uninsulated ones, can get excessively hot. Fluctuations in temperature can also be very damaging.


Labelling doesn’t save your ammo from deteriorating, but it does help you know the age of your ammo, mark it with the month and year you bought it, and you can keep tabs on its age.

Of course this does mean keeping your shells in their boxes. Still useful though.

How does ammo break down

If you are a gun enthusiast you may already know the answer to this, if not, keep on reading!

There are three main things that will cause ammo to break down, they are; heat, moisture, and of course, time… but what doesn’t time break down?

All or even just one of these factors can result in less power, less speed, shoddy consistency, and a downgrade in the reliability of your ammunition.

While these factors are perfectly capable of resulting in less effective rounds, they can also make the ammo unable to fire, or what we better know as a misfire.

Thinking about moisture in your ammo, it will have some adverse effects, it can cause the primer and powder to become damp, which is unpleasant in itself.

But it also leads to problems with firing. Moisture can be any visible liquid, like rain water, lake water from a hunting trip, or just an annoying spill.

However, humidity can also cause moisture to seep into the ammunition, this is why we don’t like humidity. Not only does it dampen those important parts, but it can start to corrode the exterior of the cartridge, so not only will you have damp ammo, but also corroded ammo, what a mess.

How excessive this damage is, is totally dependent on the type of ammo and the material as well.

While moisture is bad, so is heat because after the powder is created it slowly breakdown, but heat speeds up this breakdown. So… avoid heat too. 

The Simple Prepper