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How to Properly Store Ammo

by Kyle Wintersteen   |  December 22nd, 2013 17

Before every waterfowl season—which I anticipate like a kid on Christmas—I like to ceremoniously inventory my ammunition supply. Do I have enough goose loads? How am I doing on No. 2s? Could I use a few more No. 4s?

This year turned up an unexpected relic: Two dusty boxes of Federal Tungsten duck loads purchased approximately the year I graduated high school. Due to China’s fluctuating exports of Tungsten, Federal quit making them, but I now held my once-favorite shells. However, when I opened the box, disaster—the brass shell heads were green with corrosion. After spending years in storage and enduring some uneventful trips to the duck blind, the shells accumulated enough moisture to render them useless.

Their loss equated to no small financial blow, which is why I’m not normally in the business of allowing ammo to deteriorate before I shoot it. I probably have more money wrapped up in shells than any savings advisor would recommend, and I suspect the same is true for you. So, how can we protect our investments—what is the best way to store ammo to ensure it goes bang, doesn’t decline in performance and remains safe to shoot? Here are a few helpful tips.

Avoid Extreme Heat
Modern, factory-loaded rounds are designed to function reliably in conditions ranging from the arctic to the tropics. Therefore as long as you prevent exposure to extreme heat, high humidity and temperature fluctuations, your ammunition can be expected to last 10 years.

According to Rick Patterson, Managing Director of SAAMI, “In fact as long as your ammunition is stored at normal room temperatures with low humidity, it can function reliably for decades.”

It takes more than just a warm day to detrimentally impact ammunition—SAAMI believes the breakdown begins around 150 degrees Fahrenheit. There are very few environments where stored ammo can reach those extremes, but the trunk of a vehicle is one of them.

“Definitely avoid storing ammunition in a car on a hot sunny day—that’s probably the single most likely scenario that could cause problems for the average shooter,” Patterson explained. “With extremely high temperatures, you get rapid degradation of the ammunition components. The case and bullets are relatively inert in terms of temperature, but the chemical properties of the gunpowder and priming mixture can be affected … Over time, you’ll see a drop in performance, perhaps to the point of going click rather than bang.”

Theoretically, extreme cold could eventually impact ammunition, but it isn’t worth your concern. High heat kills otherwise good ammo, and that’s the primary thing to avoid in regards to temperature. Rapid fluctuations could, however, also prove detrimental over time. So if you’re among the many Americans storing shells in garages, perhaps you should reconsider.

“It’s easy to forget just how much conditions vary through the year, let alone over the course of many years,” said Tim Brandt, Media Relations Manager for Federal Premium Ammunition. “Here in Minnesota it can hit 100 degrees in the summer and  negative 30 in the winter.”

Keep Your Powder Dry
Ensuring a low-humidity environment is another storage priority. According to Patterson, “there’s no hard-and-fast level to strive for, but generally the lower the better.”

If your basement smells damp or occasionally spawns mildew, it’s not ideal for ammo storage.

“One of the biggest issues caused by humidity is corrosion of the brass casing and perhaps even the bullet,” Patterson said. “Number one that changes the dimensions of the case and creates friction, which may not allow the cartridge to seat in the chamber correctly. It could also weaken the cartridge, so take a look at the external conditions of the case—if you see evidence of corrosion, the damage may make the shells unsafe to shoot.”

In cases of very high humidity—or direct exposure to water or household solvents such as oil, ammonia or paint thinner—moisture can seep in and ruin ammo.

“Premium ammunition manufacturers take extra steps to seal the cartridges at the two most obvious seams—at the primer and around the bullet,” Patterson said. “Premium waterfowl loads are also sealed at the primer and crimp. Still, always avoid exposure to high humidity, water or chemicals.”

Therefore, consider storing your ammunition off the ground in a sealed, plastic container. I also keep a dehumidifier near my ammunition, particularly during the spring and summer months. I’ve had good luck with those from General Electric in terms of effectiveness and durability.

For most shooters, these precautions are plenty. However, if your ammunition will be stored for many years in a potentially humid environment—perhaps at your cabin on the lake—there are products designed to further inhibit corrosion. Most are sealed bags or plastic and metal containers designed to lock out moisture. One such product is the Federal Champion .22 Long Rifle Fresh Fire Pack. It consists of 325 .22 LR cartridges, packed in a nitrogen-sealed can that locks out moisture.

Then there are the many types of Russian-made, surplus “Spam Cans.” The steel cans are sealed tightly against air and water, requiring a special tool or screwdriver to pry them open. Some shooters swear by these cans to keep ammo fresh for decades. The cans are commonly shipped with 7.62×39 or 7.62x54R loads—quantity varies, but 640 rounds is typical.

What about the not-so-airtight storage containers such as those available through U.S. military surplus? Many of them have a rubber O-ring around the rim to lock out gas and moisture. You can improve the strength of this seal by applying a very light coat of gun oil or WD-40.

The Good News
Luckily, as long as you adhere to these basic recommended guidelines, you’re almost certain to get a decade of use out of every box of shells. Our grandfathers couldn’t expect that.

“When you look at advances in chemical technology, some of the world’s greatest innovations are taking place in ammunition and gunpowder,” Patterson notes.  “The consistency across a broad range of conditions is really amazing. Much better than 20 or even 10 years ago.”

So, keep your powder dry. Also avoid high heat, store in a stable, room temperature environment and prevent exposure to moisture and humidity. As long as you aren’t among the few retro shooters who enjoy paper shotgun hulls—which are extra sensitive—these rules are sufficient to preserve all types of ammo, from rimfire to centerfire to shotshells.

For further information, consult SAAMI’s brochure

  • master of sinanju

    I have stored 9mm ammo for 15 years outside in an old refridgerator (temp. 40 degrees to 120 degrees pretty much desert weather) I made sure the seal on said fridge was good, and the ammo in surplus miltary cans. I had sold my 9 mm handgun and only recently acquired another 9 mm handgun. I took it out and shot well over 250 rounds thru my new 9mm pistol. no malfunctions,FTFs at all.

  • manly386

    A decade? That’s all? I still have .303 ammo with a 1943 date stamp on it that functions perfectly. It’s been stored in my cool dry basement. I’m of the opinion that if it’s dry and cool ammo lasts indefinitely. With the exception of paper shotgun cartridges. They tend to swell and corrode if damp. manly

    • goldsix

      I have been shooting some 1932 dated 7mm Mauser military rounds with no misfires. I agree that dry storage is the key factor in keeping ammo fresh, but also surplus military ammo was sealed (my 7mm looks to have a heavy red layer of sealer around primer and case mouth) with long term storage in mind when it was manufactured.

  • BJC

    Specifically stating your ammo will last a decade is a poor choice from the author mainly because there is no truth to it. Properly stored ammo will last much longer than a decade. I have ammo 40 to 50 years old that functions fine.

    • Kyle Wintersteen

      Thanks for reading. Properly stored ammunition can be expected to last 10 years, but I am not suggesting that this is the maximum or average lifespan. It is merely the rule of thumb used by many manufacturers. As you point out, ammo can last many decades–this is noted in the fifth paragraph.

  • Chuck

    I agree with many of the commenters – and much less with the author – about the time that most ammo stays perfectly good. I used to get “seconds” from my aunts and cousins who all worked at a famous ammunition factory. This went on from when I was from 7 to 18 years old. The years were from 1955 ’til 1966. I shot thousands and thousands of those rounds with nary a single misfire that I can remember. Once I was down to my last thousand or so rounds I stopped shooting them and saved them for nastalgia’s sake. Every summer I’ll still shoot 10, 20 or 30 of them just to see how they perform. My chrono proves that they’ve lost nothing in over 47 years! (And remember, these are seconds.) My dad gave me 10 boxes of Federal shotgun shells with paper hulls which were stored in his old detatched, unheated garage for many years. I believe these are from the 1950′s or 60′s. I shot about 10 rounds of these this past fall and they still pack a wollop.

  • PDA

    The cheapest most effective storage is properly sealed 4″ PVC with a fernco cap and desiccant. Test storage 500 rounds 22 le under water for 6 months. Full function no misfires.

    • petru sova

      People who have used desiccant when storing ammo have found that it destroys the primers eventually drying them out to the point where they will not fire.

      • Joe

        I always kept my ammo and loading components high and dry.I was shooting powder from the 70′s without any problems. Few years ago when I started buying factory ammo by the 1,000′s I started vacuum packing them, what could be better……..

  • Al

    It looks pretty unanimous that the writer has set low end/safe expectations for ammo storage. Heck I am still shooting ammo my father had 60 years ago and it cycles fine. Mostly 22 cal and various shotgun shells and I guarantee it had zero special storage except a closet for most of those years. I fully expect the same or better out of my properly stored modern ammo.

  • The Rifleman

    “quote” Many of them have a rubber O-ring around the rim to lock out gas and moisture. You can improve the strength of this seal by applying a very light coat of gun oil or WD-40. (end quote)
    Gun oil. Yes. WD-40. NO! The high alcohol content in WD-40 will actually destroy the rubber o-ring. WD-40 is a great product and has may good uses, but this definitely isn’t one of them. A silicone based product would be a much better choice for this purpose.

  • HankB1

    I use USGI ammo cans and slip in a small container of silica gel – I have handloaded ammo decades old that functions perfectly after being stored this way. Also – like another commenter already stated, using WD40 is not a good idea to seal the gasket; its probably unnecessary, but if you think it needs it, something without solvent (think gun grease or ordinary Vaseline petroleum jelly) is a much better choice.

  • Guest

    I have been using USGI ammo cans for many years. This is the first time I have ever heard anyone calling them “not-so-airtight”. I guess if the seal went bad, yea, it wouldn’t be airtight, but I’ve never had that happen. One reason ammo might not last as long as the old stuff might have something to do with when they removed the mercury from primers several years ago.

  • huntingdave

    I think Kyle did a fine job. He’s right heat kills right along with temperature fluctuations and moisture, pretty much common sense which so many people seem to lack these days. And paper hulls are ultra sensitive and may swell so much they can’t be chambered, any old-timer that’s ever been rained on can tell you that. However, silicon gel/spray is the only thing to use on any o-ring seal like a gun case, scuba etc… some use vasaline but it will eventually cause deterioration like petroleum sprays. Ammo will live longer than you will if stored in environmently stable conditions.

  • rex oherlihan

    B.S. alert. B.S. alert. NEVER use WD40 in or around any ammunition. The vapors have proven to kill ammo, making it absolutely worthless. The writer of the article obviously doesn’t have enough experience in this area.

    • Voice_of_Reason

      wd40 also gums up over time. when I was younger, I cleaned some guns with WD40 and stored them – after all, the can said it was great for firearms. After storage for a couple of years, the WD40 had turned to the consistency of pine sap, which messed up the guns function. Required solvent to remove the WD40.

      Bottom line: WD40 is absolutely awful for firearms.

  • Alicia

    Would storing Pyrodex pellets, Pyrodex black powder and .44 long colt be safe to store in a refrigerator at a proper setting for a long period of time?

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