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I keep my pistol and extra mags in the truck when im at work and my truck sits in the sun all day. I know it gets pretty dang hot in the car in the Texas sun, even with the windows and moon roof cracked. so do yall think there is any risk of a round going off?

Unless your vehicle has spontaneous combustion, the answer is no. What you're talking about is commonly referred to as "cooking off". The heat inside your vehicle is nowhere near enough to make that happen.

HighVelocity wrote:Unless your vehicle has spontaneous combustion, the answer is no. What you're talking about is commonly referred to as "cooking off". The heat inside your vehicle is nowhere near enough to make that happen.

O ok, well just wondering how hot does it need for "cooking off"?

A cook off is usually the result of rapid or full auto fire that gets the chamber up to temperatures that will blister your flesh. Leaving a round in the chamber under these conditions will sometimes result in a cook off.

Cook offs are the reason many belt fed automatic weapons fire from an open bolt.

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O ok, well just wondering how hot does it need for "cooking off"?[/quote]

I have seen cook-off's in M-60's, 249B's, and .50's--but they were smokin' red hot with no barrell changes. Usually the barrel will melt first. I have never seen or heard of an M-9 Beretta or an M-16 cooking off.

If I remember correctly, you'd have to get the ambient temperature in the chamber above of 500-degrees to "cook off" typical small-arms ammunition. These temperatures are easily attainable in machine-guns under sustained, high rates of fire with higher-pressure, high-velocity rounds such as 7.62NATO(.308Winchester) and larger. Most machine-guns can fire 700 rounds or more per minute and it's possible to literally melt the barrel as DSARGE mentioned.

The time spent reloading and the limited ammunition reserve typically never allow the average auto-loading rifle or pistol get hot enough to "cook off." As an example, it took three experienced shooters and myself about ten-minutes to run 1500 rounds through a new Glock 19 shooting as fast as we could. That still only works out to 150 rounds a minute because of all the time spent reloading the gun and recharging magazines. It's also no where near the rate of fire seen in machine-guns. The gun certainly got toasty but never came close to being able to "cook off" a round. My experience is similar with my rifles. I've run my, M1A's, SA58s (FAL-clone) and M-Forgeries (AR15) to the point my barrels smoked and glowed red in training yet, I still have not seen a round "cook off" in either platform. The point lurking here is that a gun sitting in your car is not likely to get hot enough to "cook off" unless the car happens to be on fire.

G.C.Montgomery wrote:If I remember correctly, you'd have to get the ambient temperature in the chamber above of 500-degrees to "cook off" typical small-arms ammunition.

The MSDS for IMR single-base powder says ignition temperature is 160-170 Celsius (320-338 Fahrenheit). That's almost hot enough to affect the temper of your springs, so a gun that got hot enough to cook off is pretty well ruined already.

Don't bake it in the oven, and you'll be fine.

No cook-off problems, but storing your gun consistently in a car or truck under the Texas summer sun can have an effect on the life expectancy of your ammo. The two biggest enemies of ammunition are moisture and heat. It seems to take conditions of 120 degrees (F) or better to do it, but constant exposure to that level of heat will start a slow degredation of the priming compound.

Not an issue for a day here and a day there in a parked car, but after about a year of storage in that kind of heat the primers--even with high quality, modern ammunition--could start to go bad. So if you leave you gun day-in and day-out in the car in open parking, I'd suggest you use up old ammo and replace the rounds at least once per year. Waiting two years is probably okay since the ammo isn't exposed to the heat 24 hours a day, but it's more fun to use it on the range once a year and rotate in some new JHPs.

Thank you for all the comments. At least i learned something today!

Thanks guys, that's something I have always wondered about too!