Another Dumb Question

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Partisan Ranger

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At what temperature would your typical centerfire cartridge, say a 9mm Luger, explode? Are we talking several hundred degrees F?

I've been wondering about keeping my sidearm in my car in high temperatures. It gets pretty toasty during the heat of a July day. Is that a completely idiotic question? Probably. Sorry.
 
You might check Hatcher's notebook for reasonable data, since I can hardly claim to be an expert. Of particular interest are his experiments with live rounds fired under a box electrically. Even if on "goes off", since they simply can't explode, very little, beyond cosmetic damage, would result.

I do know that, should you throw a primer into a woodstove running hot, as it usually is around here in January, it takes roughly 20 seconds to go off.

Since that'd be the controlling variable, and I've seen the stove exhaust dull red, I doubt you'll have any problems at all.


(NOTE: this was provided by benewton, and I've no idea how I got under
Timber-Hunter's account. Gotta go write to some people...)
 
You could set up some sort of temperature recording device, like with a scrolling paper and a needle, in your car.

Set up your loaded pistol aimed at the paper right in line with where the needle touches the paper.

Then you can just look at the temperature reading right above the bullet hole.

Let us know what you find out. :D
 
Not a dumb question. It's always better to be safety-conscious than to pretend you know the answers.

It takes a lot more than sitting in a closed car, even in hot summer sunlight, to cook off ammo. I know, because I do it all the time!

A closed car can get up to 180 degrees F, but, if I remember correctly, it takes closer to 300 to cook off ammo.
 
Are you leaving the gun or ammo in your car? The regular heating and cooling might degrade your powder or primers.
 
From here (actually a fairly interesting article that I ran across while doing a search): http://www.aeroballisticsonline.com/ballistics/propellants.html

Greg

****

Cooking-Off:

Cooking-off is when a cartridge explodes in the open or fires in a firearm, without the trigger being pulled, do to the application of heat. A cartridge may explode in a fire such as a house or store fire, in this case there is no confinement of the lose case and the explosive pressure will be in all direction similar to a fire cracker but ammunition like fire crackers can still be dangerous. If the cartridge is in the chamber of a firearm then it is as if the trigger was pulled. Cook-off can accrue in a firearm if the firearm has been in direct sunlight on a hot day. From test done by the NRA, Army Ordinance, and others it has been shown that cook-off accrues' in the high 200º F to the low 300º F. Shot-shells the average temperature is the high 300º F. Cook-off will not accrue in boiling water but by the cartridge being in contact with the metal bottom of a pan could be very dangerous. Water may leak into the cartridge case and wet the powder.
 
Good article link, Greg.

For the record, the ammo I leave in my car is NOT in direct sunlight, and is insulated by the box it is in, and the layers of material on top of it. When the ammo is taken out of the box, even on a hot sunny day, it is not hot, or even warm, to the touch.

That's the kind of environment I would recommend.
 
My Kel-tec P32 melted when used outdoors on a sunny day with the temps in the 90s. The trigger got soft and bendy so that I couldn't pull it back far enough to fire the gun. It was fine after it cooled down at an indoor range a few days later.

I'm now not much of a fan of plastic guns.
 
I don't keep my K-9 in the car regularly. I just take it in the car on errands and I have to leave it in the car when I'm at work.

I didn't think it would be a problem (otherwise our troops in Iraq would be having serious problems!) but I thought I'd ask.
 
WOW, 180 deg. F ! more than I thought. There have been reports locally of people leaving their children in a hot car and I quoted what I heard on the report. I am going to put a calibrated digital thermometer in my truck and post the results later.

P.S. I have kept a firearm inside a vehicle for many years and have never had a problem. The most I could say would be a weakened or reduced capacity load from some sort of powder degradation.
 
In my mis-spent youth....

as a Border Patrol Agent, I sat for long hours in a Dodge Ramcharger. The interior temperatures of the vehicle were recorded at 140 degrees F. No cookoffs from the rounds in my sidearm or bullet loops.

This was in the Imperial Valley (desert) of California, by the way.

Also was at the range and made the mistake of setting a revolver down on the bench in the sun. I don't know the temperature, but it was too hot to hold in my hand. Still didn't cook off.

In the Marine Corps during training cycles, there was always some dimbulb who would toss blanks in the fire. Those would cook off. Kindling point of regular paper is 451 degrees F; so the fire has to be that at a minimum.

This sort of provides a range of temperatures. I don't think a car would get hot enough to cook off ammo (absent the car being on fire). Still, as has been mentioned, I don't think the continual up and down of temperature would do the ammo any long term benefit.
 
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