Ammo storage in extreme temperatures

[Willie Lowman]

My line of work takes me to many different facilities through the year. Most of our customers have strict no firearms on premises rules. Getting caught violating these rules will usually result in a lifetime ban from said property. In some cases, depending on the customer, it could result in me being fired so my company does not loose business with that customer.

So, I have to leave my gun in my car when I get to work. It is secured and the car is locked.

My question is about how well the ammuniton will hold up through summer heat and winter cold. I live in Ohio so in the summer it gets into the 90s and sometimes over 100 for a few days. In the winter temperatures can get down to 0 and below. Temperatures inside a parked car in the summer can be 120, or I've heard as high as 150.

So how long can I expect my carry ammo to hold up to such extreme temperatures?

[Skippy]

Well, here's what one guy says:

"High temperatures will begin to affect the gunpowder and priming mixture. Over time you’ll notice a drop in performance due to severe degradation until eventually your rounds or shells stop firing altogether. A good rule of thumb is to make sure your ammunition is always stored somewhere below 150 degrees Fahrenheit"

https://www.safeandvaultstore.com/bl...nd%2085%C2%B0F.

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I'd give my right arm to be ambidextrous

[kenny53]

I left some shotgun shells in my garage for about 10 years. Temps from 100+ to below freezing and they fired just fine. If you are worried fire the ammo and replace every 6 months to a year.

[TunnelRat]

Originally Posted by kenny53

I left some shotgun shells in my garage for about 10 years. Temps from 100+ to below freezing and they fired just fine. If you are worried fire the ammo and replace every 6 months to a year.

I second this.


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[Nick_C_S]

When I lived in California, I had a similar situation where my carry piece needed to be stored in my black car, in full sun, on days that regularly exceeded 100f (and sometimes 110).

I replaced the ammo every October. The ammo I cycled out seemed to shoot just fine out at the range.

FWIW, it's my understanding that the primers are more affected by heat degradation, rather than the propellant itself. Not that it really matters which degrades first, I suppose.

[Rhodester]

Perhaps putting the gun and ammo in a good empty cooler in you trunk could delay the items from reaching ambient temperature. I live in Ohio and understand your dilemma.

[Doc Intrepid]

In the for-what-its-worth department...

I had the same situation as you - i.e. needing to secure a firearm in the car when parked at my place of employment due to company policies. I locked the handgun in a console vault (link below). As an unanticipated bonus, the console vault kept my handgun somewhat insulated beneath a fold-down arm-rest and the lid to the center console in my truck. The interior of the truck might get warm in summer, but the pistol in the console vault was never warm to the touch at the end of the day. It might be something for you to consider.

Here's the link:

https://www.consolevault.com/gun-vault.html

(I realize you already said your handgun was secured -- this device simply seemed to offer some additional insulation I was not anticipating....same idea as Rhodester with the cooler suggestion.)

[Ukrainitz]

Same situation here in Western PA. Went 6 years with "old" ammo in my Glock. It fired just fine, but now I change out every year. Not sure it's an exact science with the heat/cold effect but I don't want to take a chance.

[JohnKSa]

I don't know if there is any good guidance from any manufacturer on this topic, but I can give you my conclusion based on "experiments" in TX.

Choose premium quality self-defense ammunition from a manufacturer with a good reputation and change it out once a year or so.

I'm definitely not saying that going 13 months will mean the ammo is defunct by that point, I think that even 5 years would probably be ok. But I'm just not going to recommend that.

[44 AMP]

Generally speaking, many chemical reactions are accelerated by heat and retarded by cold.

This included the very very slow chemical reactions going on in modern gunpowder and priming compounds "at rest".

About everything else is a variable. Ammunition, properly manufactured, in the last 150 years or so is pretty stable, when stored under ideal conditions. Exposure to high temps (generally 120f and above CAN have an effect on their shelf life, but there is no way to predict how much in advance.

And, there is a difference between ammo that goes through temp swings and back again, and ammo being used at high or low temps.

That "ten year storage in a garage and it was fine" is common, MAYBE it took a few years off the ammo's shelf life , so maybe 40 years later it will be going bad instead of lasting 60 years or more.

OR, maybe not. Any test you might use to determine that would take decades, and then only apply to that specific batch of ammo you tested.

The quality the ammo is made with to begin with, along with what it endures during its storage life determine how long it will last. HOWEVER, no one can tell you how long that will be.

They can tell you the designed storage life, the amount of time which with proper storage the ammo is expected to last (and if it doesn't its considered defective) but they can't and won't tell you how much longer than that the ammo can last.

I've shot WW I ammo in the 70s (so 60years old) and it worked 100% normally. And, I've had a batch of ammo made 99-01 and fired about 10 years later that had 11% failure to fire, and 17% of the fired brass cracked.

More extremes than these and anything inbetween is possible.

If you're worried about it, do as most do, simply replace it periodically.

When you're talking about what you have to leave in the car, its not much ammo really. A full box? Two? A bit different than having several cases of ammo stored in the barn year round for decades....

back in the 70s, I read an article from a guy who bought 100lbs (4 25lb caddies) of surplus rifle powder shortly after the end of WWII. He used one up, the other 3 were stored in his parents barn in PA. (not temp controlled). Life happens and the stuff sat until he was able to get back to it, 25 years later. He ran extensive load tests and wrote up the results. The old powder delivered 100fps lower velocity than the current canister grade powder of the same name. That's not a lot of change. Your milage may vary but stories like this, old powder/primers/ammo being ok are very common.

[44caliberkid]

Another thing to think about is will your pistol function in extreme cold. I left a Browning Hi Power in my car all day in cold winter. Went to the range after work and the slide would barely move. The lube had literally turned into molasses in January. Even a revolver might be a little stiff when below freezing. Make sure to test your gun lubricant in below zero weather or run completely dry.

[Shadow9mm]

Ammo should be stored in a cool dry place. Heat degrades most modern smokeless powdes and primers. Being in humid environments is not great either. Being in low temps will preserve ammo it slows down the degrading of the powder and primers.

What I would recommend, a well insulated lunch cooler. Something like a yeti knock off. Keep it in the house after work in the ac part of the car while driving to keep the temp of the cooler low. I would avoid ice packs as they tend to induce condensation. You could also get a cheap fleece blanket in a light color as it will further insulate your cooler, and keep the sun off of it.

[Onward Allusion]

Originally Posted by TunnelRat

I second this.


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Not sure about 10 years but I'd just fired off a couple of boxes that sat in my trunk for a little over a year and they all went bang. They were a little smokier, however. I would probably rotate 'em out a little more often. Maybe every 6 months or on a quarterly basis.

[jmr40]

The effects of high and low temperature on ammo is very, very low, at least short term. As long as it returns to "Normal" temperature before it is fired. I live in GA. The outside temps are in the 90 here quite often and in isolated spots can be well over 100 degrees at times.

Inside a closed car parked in the sun temps can reach 140-150 degrees. It isn't unheard for canned products such as aerosol cans, canned drinks, even scuba tanks stored inside cars to explode from the heat.

Winter temps in the 20's are common in the northern part of the state where I live and single digits happen occasionally. I've seen it -9 before. People leave guns and ammo in their cars here year round and I've never heard of a problem.

I suppose leaving ammo stored in such conditions long term might eventually degrade it enough to be a problem. Rotating the ammo every few months wouldn't hurt.

But firing that ammo when it is hot, or cold, might lead to an issue. I'm more familiar with rifles than handguns. But most ballistics data is done at around 70 degrees. For every one degree temperature changes from 70, the muzzle velocity will change by 1/2fps to as much as 3 fps depending on the powder used.

That means that if your gun is locked in a hot car that reaches 140 degrees your velocity will increase from 35 to possibly as much as 200 fps. If there is one of the more temperature resistant powders in your ammo the 35 fps isn't dangerous. Military specs call for temperature resistant powders. But with some powders that additional 200 fps could make for a dangerous load.

Of course firing in extreme cold results in similar changes, but the speeds will be 35-200 fps SLOWER if fired at 0 degrees. That wouldn't be dangerous, but could change ballistics especially with rifles.

[Willie Lowman]

Here's the link:

https://www.consolevault.com/gun-vault.html

(I realize you already said your handgun was secured -- this device simply seemed to offer some additional insulation I was not anticipating....same idea as Rhodester with the cooler suggestion.)

Thanks for the recommendation! I ordered 2 of them and they came this morning. Already got them installed. Better security than the lock box I was using.

[Willie Lowman]

I emailed Federal this morning. I'll post their reply when I get it.

[Willie Lowman]

Well I got an answer from Federal.

Long time, however we recommend not using it for ammo storage every day. Rotate thru the ammo and it will be fine.

I'm not really sure what they mean by that. Carry different ammo every day?

[Aguila Blanca]

Originally Posted by Willie Lowman

Well I got an answer from Federal.

I'm not really sure what they mean by that. Carry different ammo every day?

What was the question you asked them?

[Willie Lowman]

What was the question you asked them?

Exactly what I started this thread with. I copy/pasted my first post into the email. I just added at the beginning that I carry HST 124 grain +p

[JustJake]

Ammo should be stored in a cool dry place. Heat degrades most modern smokeless powdes and primers. Being in humid environments is not great either. Being in low temps will preserve ammo it slows down the degrading of the powder and primers.

Definitely this ...

Cool, dark, dry. Ammo stored that way will keep for decades.

[Willie Lowman]

Well, that's great because I store my ammo sealed in cans in a dark closet with desiccant in my climate controlled house...

But my question isn't about best practice for long term storage. Rather how well does it hold up in extreme heat and cold.

[RoyceP]

I had an opportunity to shoot WWI ammo - 303 British - in an Enfield rifle that was in remarkable condition for having been stored since participating in WWI.

The ammo was scary. Hang fires were relatively common. Occasionally a round wouldn't work at all. My friend had purchased 500 rounds. After 20 of them he decided to toss the whole lot in the dumpster at the range.

I would cycle out the carry ammo every six months or so. Shoot it or just pull the bullets, dump the powder in the garden, and dispose of the primers. Reload the brass with the same bullet and fresh primer and powder for practice.

[Sgt127]

When I was in SWAT, all my Tac gear lived in the trunk of my car. Loaded magazines for the MP5 and spare pistol mags. (The MP5 didn’t stay in the car).

Those mags stayed loaded for years and only came out for work.

At practice, I used other mags and, practice ammo.

Those mags lived in a trunk of a Crown Vic for a couple years, in Texas. Never an issue.

Now, .22 LR? I had a few bricks of Wildcat I forgot about in the garage for years. Several duds. I pulled one and it seemed like the wax lube melted and ran down into the powder. And, all the rounds felt really greasy. If o had to guess, the ones facing down in the 50 round boxes were good.