Temperature And Humidity Specifications For Ammunition Storage
BY Herschel Smith
1 year, 3 months ago
Paul Harrell gives us a really interesting video on ammo storage. What he finds is that if the ammo works, it seems to work well. Unfortunately, he had some failures to fire in the batch he left in his car for a year. He suspects (and I suspect too) that further exposure to high temperature and humidity would have further degraded the ammunition performance.
I spent just a little time to locate U.S. Army temperature and humidity storage specifications for ammunition, and while I found a bit of information, I ran out of time on that research project. I suspect there is much more than what I found.
I did manage to locate an American Rifleman Q&A.
Q: I live in rural upstate New York, and summer temperatures reach in excess of 90° F—with car and attic temperatures exceeding triple digits. Is there a known “maximum safe temperature” for the storage of ammunition? What would be the ideal conditions to store ammunition?
A: Nitrocellulose, the primary ingredient in smokeless powder, is hygroscopic, which means it absorbs water from the air that can affect both shelf life and burn rate. Coatings and stabilizers, such as methyl and ethyl centralite, are added to prevent this. Unfortunately, the effectiveness of these compounds is reduced as the temperature rises.
The standard advice is to store ammunition in a “cool, dry place.” Manufacturers try to store powders at 70° F +/- 5 degrees. For handloaders, the best advice is to store powder in a cool basement or an interior room that is of “comfortable” temperature.
The only thing I can think of to say is if you live in New York, get out.
On August 27, 2023 at 11:54 pm, Dan said:
Temperature is an issue with ammo storage. Humidity is a bigger issue. If you can only control one control the humidity…with a goal of keeping the environment NON humid. If you live in the desert storing ammo is much less a challenge than if you live in a place like Florida.
On August 28, 2023 at 1:25 am, FeralFerret said:
I have 60 + year old .38 special ammo that belonged to my father. Forty of those years it was stored in a closet in a very dry climate. The remainder was indoors in a basement cabinet in a humid climate. They still perform reliably at the range.
Keep it at stable room temperature and low to moderate humidity.
There is good reason that some military ammo is required by contract to have the primers sealed with lacquer. It helps to seal out any humidity. I used to work for a DoD contractor that made 40mm ammo.
On August 28, 2023 at 4:45 am, jrg said:
We’ve also wondered the same thing ourselves . One of my acquaintances stored some Remington Shur-Shot 12 gauge cases from back in the early 1990’s (really good price was found). He kept it until around mid 2000 ‘teens’ (approximately 25 years) where he fired the contents of one case. He had a few failures to fire, maybe two-three per 25 round box. Not a hang fire – it works until it doesn’t.
The storage was inside a residence, but in often unconditioned air space where daily outside air temps registered in the high 90’s – low 100’s during the summers. Interior temperature was very high 80’s. House had two a/c units, but the storage side was often left turned off to reduce electricity bill. Winters were far cooler. So this is mainly a heat issue. Humidity is very high outside, but indoors probably less.
I hope this helps. Good Question !!
Our very limited experience here.
On August 28, 2023 at 8:00 pm, Matt said:
Well this tells me that I should shoot up the ammo in my ride during my next trip to the range.
On August 28, 2023 at 9:17 pm, Rocketguy said:
For best performance and reliability, cool and dry is definitely best. However, recently, I found a couple boxes each of 45 and 38 Special that had been misplaced more than 10 years ago in my non temperature controlled attic. They saw some pretty ugly temperature cycles involving triple digits and near freezing. They all fired with no obvious issues. Wouldn’t want to stake my life on them but it’s more data.
On August 28, 2023 at 10:11 pm, Latigo Morgan said:
I had a box of Wolf steel cased 45 ACP that rode around under the seat of my work truck from the time I bought it. It was there for about 3 years, exposed to extreme heat and cold and even covered in a can of Chunky soup that froze and exploded.
They were there when bomb/gun sniffing dogs were run through my truck to access some secure, sensitive government facilities, but they never detected the ammo.
The rounds had some rust on them, but I had to test it in my 1911. Every round fired with zero defects or stoppages.
I had some of the same tests with some 22LR and some 12 gauge I’d forgotten in my truck tool box for a good 5 years, same results – no problems.
On August 29, 2023 at 5:24 am, SamlAdams said:
Have always used surplus ammo cans as storage since was a kid. Never had a problem with any ammo (raps head with knuckles) Several years ago found a couple boxes of Revelation .22 ammo from Western Auto that had to be 45+ years old—cheap stuff we used to plink at grandparents farm. Functioned flawlessly. I’m not a volume reloader so usually buy 1lb canisters so it’s used up within a year of opening.