By Dominic Schwebs | Digital Marketing and E-Commerce Manager at Safe & Vault Store, with over 15 years of experience in the security industry.
Properly stored ammunition lasts far longer than most gun owners realize. The 10-year shelf life you'll see on manufacturer FAQs is a conservative, liability-driven estimate, not a technical limit. Under the right conditions, modern ammunition can remain fully functional for 50 to 100 years or more. The variables that actually determine shelf life are temperature stability, moisture control, and container quality.
At Safe & Vault Store, we've sold more than 150,000 safes and helped customers protect everything from firearms to irreplaceable documents and valuables. The same conditions that make a quality gun safe the right place for a firearm make it one of the best places for ammunition too.
The Quick Version: What Proper Ammo Storage Looks Like
- Keep ammunition between 55°F and 85°F.
- Store it in a cool, dry location away from direct sunlight.
- Use airtight containers. Military surplus steel ammo cans are the gold standard.
- Add silica gel desiccant packs to your containers to control moisture.
- Avoid garages, vehicle trunks, and basements with humidity or temperature swings.
- Keep ammo in original factory boxes inside your airtight container for organization.
How Long Does Ammunition Actually Last?
The 10-year figure comes primarily from Federal Premium's FAQ and similar manufacturer statements. As NRA Family contributor Jeff Johnston writes, ammo companies push a conservative message "likely because they don't want the liability if it fails to fire." It is not a technical expiration date.
SAAMI (the Sporting Arms and Ammunition Manufacturers' Institute, the U.S. industry's own standards body) does not cite a specific shelf life at all. Their position is that degradation is caused by environmental conditions, not time alone.
The documented evidence backs this up. In a 2021 test published by AmmoLand, researcher Dean Weingarten fired Remington .22 LR manufactured before 1956, stored for 65+ years in sealed quart jars, and recorded only 1 failure in 500 rounds, with velocity actually slightly above modern control ammo. NRA Museums Senior Curator Doug Wicklund has fired factory loads from the 1870s. U.S. .50 BMG ammunition from the 1940s was reportedly used by American troops in Afghanistan and Iraq during the Global War on Terror.
What actually determines ammunition shelf life is storage conditions, not the passage of time.
Humidity and Moisture Are the Biggest Threat
Moisture is the primary cause of ammunition failure. It degrades primer compounds, accelerates corrosion, and can render rounds unreliable long before heat or age become a factor.
Gun safes are one of the most effective solutions here. Their steel construction reduces exposure to humidity compared to cardboard boxes, open shelving, or loosely closed containers. That said, gun safe doors are not airtight, so moisture can still get inside over time. Adding silica gel desiccant packs or a dehumidifier rod inside the safe is the most reliable way to keep interior humidity under control.
Tip: Use color-indicating silica gel so you can tell at a glance when packs need to be recharged. Recharge them by baking at 220–250°F every 6–12 months, depending on your climate and how often you open your storage containers. Some desiccants like the Eva-Dry models can be plugged in to recharge.
Avoid storing ammunition in basements, vehicle trunks, or any area with high or variable humidity. In humid regions, this is especially worth prioritizing, as humidity is nearly as damaging as direct water exposure.
Avoid High Temperatures
Many gun owners worry that heat will cause ammunition to spontaneously combust. That is largely a myth. Modern ammunition is manufactured to handle a wide temperature range. But prolonged exposure to extreme heat does cause real damage. It degrades gunpowder and priming compounds, leading to reduced velocity, misfires, and eventually rounds that won't fire at all.
According to SAAMI's ammunition storage guidelines, storage temperatures above 150°F should be avoided. The recommended range is between 55°F and 85°F.
To put that in context: on a hot sunny day, the trunk of a car can easily exceed 172°F, which is enough to begin degrading ammunition. If you've ever left a box of .22s in the car through a summer, there's a good chance those rounds aren't performing at spec anymore.
Prevent Temperature Fluctuations
Consistent temperature matters as much as avoiding extremes. Temperature swings cause expansion and contraction inside ammunition containers, which can work moisture past seals and stress case crimps over time.
Garages, sheds, and vehicles are all poor storage locations for this reason, as temperatures in these spaces can swing dramatically between seasons. Even indoors, areas near exterior walls, windows, or HVAC vents can see enough variation to be problematic.
It's worth knowing that most gun safes are not insulated for temperature regulation. They follow the ambient temperature of the room they're in. A safe in a climate-controlled space will benefit from that environment, but a safe in a garage or basement will not. Gun safes can also trap humidity if not properly managed, which is why a dehumidifier rod or desiccant packs inside the safe are strongly recommended. They also keep ammunition away from children and unauthorized users, which is just as important as keeping it in good condition.
Choosing the Right Storage Container
Your container is the primary defense against moisture. Not all containers perform equally.
Military surplus steel ammo cans (M2A1 .50-caliber and M19A1 .30-caliber) are the most recommended option across NRA publications, firearms retailers, and experienced shooters. They are seam-welded with a synthetic rubber gasket that creates a near-airtight, waterproof seal. Mil-spec requires 10-year unsheltered storage capability.
Plastic ammo cans from brands like MTM Case-Gard and Plano are well-designed for organization and range transport, but they are water-resistant rather than airtight. In a real-world desiccant test cited by Skilled Survival, color-indicating desiccant packs placed in plastic MTM/Plano cans became saturated in under two weeks, while desiccant in a steel can remained dry over the same period. Plastic cans are fine for short-to-medium-term storage in climate-controlled spaces, but not ideal for long-term storage.
The expert consensus: Keep ammunition in its original factory boxes (for caliber and lot identification), placed inside sealed steel ammo cans with desiccant packs. This combines organization with maximum moisture protection.
Does Ammunition Type Affect Storage Requirements?
General storage advice (cool, dry, stable, airtight) applies to all ammunition. But there are meaningful differences worth knowing.
Centerfire ammunition (brass-cased) has the longest shelf life. Brass is naturally corrosion-resistant, and the primer is a separate sealed cup that can be lacquered for additional moisture protection. Under proper storage, centerfire brass-cased ammo is the most robust format for long-term storage.
Rimfire ammunition (.22 LR, .22 WMR, .17 HMR) is more vulnerable to moisture. SAAMI's official guidance explicitly states: "Rimfire ammunition is much more susceptible than other ammunition types to moisture damage from exposure to the elements, due to the unique construction of the cartridges." The priming compound is spun into the hollow rim of the case with no separate primer cup and no practical way to add a moisture seal. Store rimfire in airtight containers with desiccant, and never leave it exposed to rain or wet conditions.
Shotgun shells degrade faster than all-metal cartridges because of their plastic hulls. LDPE/HDPE hulls can warp, crack, or become brittle from heat and UV exposure. Star crimps can loosen over time, compromising the shell's seal. Keep shotshells out of vehicles and direct sunlight, and inspect older shells for cracking or loose crimps before use.
Steel-cased ammunition depends on its lacquer or polymer coating for corrosion resistance. Brass doesn't rust; steel does if the coating is scratched or worn. For very long-term storage spanning decades, brass-cased ammunition has a clear advantage. Steel-cased rounds in sealed containers can still last for decades, but inspect for coating damage before long-term storage.
Using a Gun Safe for Ammunition Storage
A gun safe is one of the best long-term ammunition storage environments available to most gun owners. Keep in mind that gun safe doors are not airtight, so pairing the safe with a dehumidifier rod or desiccant packs is important for managing moisture inside.
If you're storing both firearms and ammunition in the same safe, look for models with configurable interiors that give you dedicated shelf space alongside gun racking. A few worth considering:
- Browning HC65 Hell's Canyon 65-Gun Safe: Wide footprint with lots of configurable shelf space, making it easy to dedicate sections to ammunition alongside long guns.
- Browning RW49T Rawhide Tall Wide Gun Safe: Axis-compatible shelving that adjusts to accommodate ammo cans alongside firearms.
- AMSEC BFX6636 Gun Safe: 2-hour fire rating, made in the USA, and one of the strongest fire protection options for ammo storage.
- SnapSafe 75014 Super Titan XL Double Door: Modular and adjustable, with MgO fire panels that are notably moisture-resistant.
If you're looking for a dedicated ammo storage safe (something compact and budget-friendly that you'd configure with all shelves instead of gun racking), these are worth a look:
- Hollon Dominion 11 Gun Safe: Compact footprint, affordable, and can be ordered with all shelves instead of gun racking. A solid dedicated ammo locker.
- Stealth UL14 Gun Safe: 20" wide, UL RSC burglar rating, 1-hour fire rating. Available with an all-shelf configuration.
- AMSEC TF5924E5 Rifle and Gun Safe: A step up in size at 24" wide and 18" deep. Available with an all-shelf kit for dedicated ammo storage.
Pair any of these with a dehumidifier rod or desiccant packs inside the safe to complete the setup.
Frequently Asked Questions
Does ammunition expire? There is no technical expiration date for modern ammunition stored under proper conditions. The 10-year figure cited by some manufacturers is a conservative liability estimate. Ammunition stored correctly (cool, dry, in airtight containers) routinely lasts 50 to 100 years or more. SAAMI's position is that degradation results from environmental exposure, not time alone.
What temperature should ammo be stored at? Between 55°F and 85°F, per SAAMI standards. Avoid temperatures above 150°F, and avoid locations with significant seasonal swings like garages, sheds, and vehicles.
Can I store ammunition in a gun safe? Yes. A gun safe is one of the best options available. Keep in mind that gun safe doors are not airtight, so adding a dehumidifier rod or desiccant packs inside is important for moisture control.
What is the best container for long-term ammo storage? Military surplus steel ammo cans (M2A1 .50-cal, M19A1 .30-cal) with silica gel desiccant packs. Keep ammunition in its original factory box inside the can for caliber identification and organization.
Is .22 LR harder to store than centerfire ammo? Yes. SAAMI officially recognizes rimfire ammunition as significantly more susceptible to moisture damage than other types. Store .22 LR and other rimfire rounds in airtight containers with desiccant, and never expose them to rain or wet conditions.
Not sure which safe works best for your firearms and ammunition? Our non-commissioned team is happy to help you find the right fit. Call us at 800-207-2259 or browse our gun safe selection.
