How much heat/humidity before ammo is compromised?

M

MikeGoob

New member
I know most people keep guns/ammo in tolerable conditions but sometimes during the summer, we are forced to lock a gun in a hot car(or similar 100+ degree heat).

So of course, no worries just use up ammo on a regular basis and you wont run into problems. Yeah, ok my SD ammo can be over $1 a round--I want to hold on to it as long as is safe before shooting it at paper.

How much 100+ degree heat can ammo take before you would consider it unreliable?
 
As a test, I have shot premium centerfire pistol ammunition that was left in a car for at least 2 complete years in North TX. Some temps below freezing, a lot of temps well above 100.

It all functioned just fine. I did not chronograph it, but if there was any power difference I couldn't tell it.

Again, that is premium centerfire ammunition. I don't know if bottom of the barrel practice ammo would hold up that well; and I don't think rimfire could be expected to provide results that good.
 
I have always said that a person should make a reasonable effort to store ammo properly. When I say properly I mean in a secure container and away from extreme temps and moisture. That said, I have not found ammo to be "fragile" in regards to its ability to fire even when poorly cared for.

I have had ammo sit in a truckbed box for 15 years while being exposed to terrible heat and cold of the humid South. When I came across the lost box of norinco I doubted that ithe ammo would fire. Every round fired without any problems.

A couple of years ago I came across my Dads cartridge belt which was full of 30-30 hunting ammo. The belt had been left in a foot locker which was stored in the rafters of a pole barn sometime in the 80s. All the ammo fired.

efforts should be made to protect ammo and to that end I keep mine in USGI ammo cans with one little desiccant pack. I keep my ammo in detached garage which is shaded by trees but not heated or cooled. I don't much worry about
 
Let's just follow what is commonly said to happen in a car on a hot sunny day. The car can reach 150 or higher. I have seen information credited to saami that ammunition can start to deteriorate at this temperature range, but that does not mean that the ammunition is ruined. What that tells me is that you should replace your carry ammunition in october. A lot of ammo is stored on site in desert regions in uncontrolled locations, even tin quonset huts. Ammo will not fire until the temps reach well over 300.

Your risk as far as I can determine is that when your texas heat reaches 100 and your car is left in the sun for days at a time, you may find ammo deterioration after a few years. Storage would be best done under a seat or trunk in an insulated case. I do suggest that you burn up your ammo every year since I can't seem to find a definitive answer for you. I've spent about twenty minutes or longer looking, I'm going to keep thinking about it and if I can get anything definitive I will post it.

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.”



Read more: http://www.gunsandammo.com/ammo/how-to-store-ammo/#ixzz5M18R2TJ7
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This is really the best information I can find, take it for what it's worth.
 
Thanks guys for the info and research. I've had some premium ammo that wife put in the attic without my knowledge. It could have been pretty hot these last few months.
 
I personally wouldn't worry about anything but your carry ammo. Even your carry ammo, you wouldn't have to worry about it except that it's something that may be life or death. Five to ten years in the attic? I'd be thinking about getting rid of it, personally, but as you have read, I'm in the minority.

I've had rimfire ammo that went bad in normal storage after years. I've never had centerfire ammo fail to operate. I don't do shotgun.

This sort of reminds me of a thing that happened centuries ago when I was a kid. guy I knew found a jerry can of gas in his barn, god knows how old, it was out there for his tractor. Dumped it into his truck.

I've got a $20,000 investment in my car. I'm not going to run three year old lawnmower gas through my fuel injectors.
 
I’ve ran 9mm than hast been in the truck for -40 Fahrenheit to 105 Fahrenheit and everywhere in between. That is just cheap FMJ, I try to cycle my carry ammo once every couple months.


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...I'm in the minority.
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Just to be clear, I'm not advising that people store their ammo in extreme heat or claiming that it will never cause problems. Ammunition should be stored in conditions that humans find comfortable to insure maximum lifetime and to prevent any breakdown of the components.

That said, I have seen ammunition subjected to very harsh conditions with no apparent problems resulting. That doesn't mean it's a good practice or that people should disregard proper storage recommendations.

I don't know that I would recommend throwing away ammunition that had been stored in harsh conditions, but I would be careful shooting it. If I encountered any unusual behavior, I wouldn't shoot any more of it. And until I was pretty confident about it, I wouldn't rapid fire with it to insure that it was easy to avoid following a possible squib with a live round.
 
Didn't mean that you were foolish, I just know that I discard anything that doesn't feel right to me and others don't worry about it. Some people will even fire discarded range pickups.

To me, finding half a box of ammo scattered around a range and shooting it is almost like picking a bottle of tequila up off of a park bench and taking a swallow.

Obviously, a lot of that is paranoia. I've had good reason to be paranoid like this.

Powder and primers are both plastic mixes, water shouldn't hurt powder, primers and bullets should be so tight that even capillary forces can't let water in. should be. I don't think that normal cold temps can cause any chemical breakdown of nitrocellulose, but, heat can start to break almost any organic compound down when it reaches a certain temperature, and time will just worsen it.

And you are right, a good rule of thumb for anything organic, be it bourbon or bullets, don't let it get too hot. Keep it where you would be comfortable.

I was working on my mother in law's dryer about twenty years ago, and found ten or so .22 lr trapped near the vent. They had gone through the wash, then went through the dryer, and wound up trapped where steam would run over them for hours several times a week. She had five people living with her at the time.

I had a great opportunity to test extreme conditions, but I decided to just dump the powder. I kind of regret that, it would have been valuable information.
 
Wife has proof tested my reloads washing them and then drying them and they shot just fine without issue. I gots to remember to empty my pockets
 
"...How much..." There really isn't a hard and fast rule. However, it's more about extremes of humidity than temperatures. And even then it's a 'maybe' thing. In any case, the amount of time will be locked in your car isn't enough to worry about. Even if it's a repeated thing.
 
To me, finding half a box of ammo scattered around a range and shooting it is almost like picking a bottle of tequila up off of a park bench and taking a swallow.
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I won't shoot range pickups either. I think that's a wise policy.
 
Mike Goob asked:
How much 100+ degree heat can ammo take before you would consider it unreliable?
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Based on my own experience, I could not question any ammunition loaded (factory or hand load) after 1979 regardless of the climatic conditions under which it was stored.

Just got an example, I have 45 ACP cartridges that I inherited from my grandfather that were loaded in 1943. I also have some cartridges that date from the Korean war.

Both shoot to within 10% of what newly loaded cases with contemprary powder can deliver with similar bullet weight.
 
Another angle to this topic: We've been talking about how ammo is affected from PREVIOUS exposure to extreme temperatures. But... how does ammo react WHILE it's being exposed? Say in the summer when those bullets are like little red hot coals, or in the winter when they're like ice cubes. How much difference does that make?
 
It all depends on components. Sometimes it doesn't make any difference and sometimes it makes all the difference......aka pierced primers etc.

Even though I don't hunt much in the summer, I hunt a lot in the winter. I won't do any load development in the winter.

If is shoots in the summer, it will shoot in the winter, but not vice versa.

Out winters are usually not much below freezing but parts of the state can get purty cool.
 
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As a boy of 13 I had the "bright" idea of removing the butt plate of my .22 rifle, drilling into the rear of the stock and inserting bullets in the holes, then replace the plate. My teenage reasoning was if I ever ran out of bullets, the pen knife I always carried would be enough to unscrew the huge flat head screw and give me access to more bullets. Over the years I completely forgot about it. More than 50 years later I re-discovered them. The rifle had been stored in various locations, but at times in the hot trunk of a car (MD/PA area) for months at a time. Of course I HAD to check them out... of the 20 rounds (Federal .22 LR) 7 did not fire. Keep in mind this is rimfire, from what I read centerfire might have had better results under those conditions.
 
I stored a box of .22LR in a non-climate controlled locker over the course of a winter/spring/summer in Colorado. Some snow got in and raised the humidity substantially at some point. Unfortunately, I wound up with several thousand rounds of .22 that fired at a 40-50% rate...conclusion: Humidity is BAD for rimfire.
 
Can't vouch for humidity as this story comes from Colorado, but when I walked into a lake wearing my Glock 19 to unwrap a fishing line from a rock (the other end of the line had a fairly good sized small mouth bass on it) the ammo - Barnes TacXPD- worked perfectly two weeks later at my next range session. I had swapped it for fresh ammo immediately for peace of mind but it still worked perfectly and shot to point of aim.

Ten years ago, the last time I was stationed out here in Okinawa we ran into a bad batch of 5.56 that was blowing primers out. The only way we discovered that primers were being blown out of the cases was that the M-4's were jamming after 2 or 3 loose primers got behind the sears. I have absolutely no way to prove that heat or humidity caused this. It was likely a bad lot of ammo. This was one occurrence in two years and close to 300,000 rounds (I did not personally shoot all 300,000. I rotated through two deep reconnaissance platoons that did a TON of shooting).
 
I have carried and shot ammo in the jungles of three different SE Asian countries, a few deserts in extreme dry heat with no problem. I have carried and shot (home range) in the northern part of the upper peninsula of MI in January and never had a problem. However, I do not have a so-called car/truck gun, mine is always on my side or in the house.
 
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