How Long Is Ammo Good For?

It’s satisfying to build up a big stockpile of ammunition. You don’t have to go shopping every time you want to get in a little target practice. You’re covered in the event of an ammo drought. And if there’s ever a really big emergency – where the proverbial stuff hits the fan – you’ll have a much better chance of weathering the storm than if you only have guns and no ammo.

If you’re just starting to build up a respectable stockpile of ammo, then you might be wondering: How long is ammo good for? Does it have an expiration date, and is it worth owning ammo that you hope to go a whole lifetime without having to fire?

Fear not. Ammo can stay good for a very long time. We often sell war surplus ammunition from the 1940s that performs without issue, and many historic gun enthusiasts fire ammo that was made all the way back during the 19th century!

Despite this, many ammo manufacturers say their products only have a shelf life of one decade. It’s important to bear in mind that they’re running a business, and they don’t want to be accountable for malperformance that could result from improper storage. They’re avoiding making promises that they can’t necessarily deliver on.

What Impacts Ammo Longevity?

There is some speculation involved when it comes to estimating a cartridge’s shelf life. The quality of its propellant and powder both impact how long it will last in storage, and features like sealed primers and case mouths can both dramatically lengthen a round’s lifespan. Although sealant is generally applied so as to protect the ammo from rainfall out in the field, it does help to block out atmospheric moisture that could gradually impact the powder’s potency.

All of this begs the question: How do you store ammo when you want it to last as long as possible? To do that, you want to control three environmental factors: temperature, humidity and light.

Temperature

Extreme temperatures are the enemies of ammunition. Most propellants contain compounds that begin to break down under temperatures in excess of 120 °F. Freezing will also harm a cartridge’s performance, especially if its bullet is made of two different metals (i.e. a lead core and a copper jacket), as these will materials will contract at different rates.

While you don’t necessarily have to store ammo at room temperature in order to keep it factory fresh, it is best to store it at a stable temperature. Keep it in your home instead of the garage or shed and you’ll be in good shape!

Humidity

Humidity doesn’t just threaten a cartridge’s propellant. Ammo that’s stored in humid places like basements and attics is at risk of quickly becoming corroded, rusted, tarnished, and otherwise too coarse to reliably cycle through a firearm. You can remove light corrosion with an abrasive cloth, but once it’s too far gone it’s not worth bothering with anymore.

If you can’t store your ammo in a reliably low-humidity environment, then it’s time to look into ammo cans. A military spec M2A1 or M2A2 ammo can is great because it has a rubber gasket and tight-latching lid that seals out moisture. A non military spec ammo can will work just as well so long as its lid seals out moisture. In addition to that, you’ll want to store your ammo with a dessicant such as silica gel. Desiccant will absorb humidity before it can corrode your valuable ammo.

Light

Light will gradually harm ammo – especially sunlight, because it contains ultraviolet rays. Protecting your ammo from light doesn’t require any special steps. Keep it where the sun don’t shine!

The Takeaway

Although some types of ammo are better equipped to survive a long time in storage than others, there’s no rule stating that ammo becomes inoperable after a fixed number of years. It’s reasonable to assume that your ammo will stay pristine and ready to fire long after you have kicked the bucket. Just take care to protect your ammo from extreme temperatures, fluctuating temperatures, humidity and light, and your ammo will most likely stay good for decades!