If I leave a box of bullets in my car will they explode with the heat?

Question

I live in Texas so it gets about 100 degrees outside in the summer

Answer 1

If they did, my cars would be full of bullet holes, from loaded guns being left inside in the Florida summer heat.

Answer 2

No.They will not generally truly 'explode' even if placed in a fire.

The reasons as follows.

Firstly those bullets are filled with modern gunpowder powder which is a 'propellant', not an 'explosive', like blackpowder is.

If you burn a pile of smokeless gunpowder it actually 'burns', it does not explode. You can stand there and watch it. Even put a bullet projectile on top of the pile and lean over it. It will still be lying there when the powder has burnt out.

In a gun when firing a bullet the primer in the base ignites the powder all at once and the very rapid burning produces a lot of gas which under the close confines of the case and the bullets chambre, produces extremely high pressures to propel the bullet out the barrel.

When placed in a flame for extended periods what you find happens is the primer is the last thing to go off.its quite tough. First the case neck expands , creating a gap around the bullet, or the case itself splits, and the flame gets in to cause the powder to ignite, before the primer can explode.

In other words you get a very low pressure burning.
The primer finally exploding without powder left is no worse than striking them on a bench with a hammer.

Basically it causes everything which should happen to make a bullet fire, happen in the wrong order.

The bullet is already spilling out by the time the powder ignites and the powder is burning off before the primer can set it off anyway.

In practice with bullets in a fire you get lot of loud 'fizzes' and 'pops 'and the bullets are 'spat out' a short distance.
Obviously its still not safe to be around when that happens!!! but does indicate anything less, like subjecting them to summer heat is not going to be a safety problem.

Where you get massive explosions from ammunitions factories on ship mamgazines during wars is usually either because those stockpiles will include 'actual explosives' with them, like used to charge mines and artillery shells and they can explode big.

Or because there is so much normal ammo in large quantities, usually packed together in heavy boxes,or sealed containers(so that the burning gas cannot escape) it creates an effect just like a gun chamber which causes explosive pressure outwards.

Answer 3

No, but I'm sure you are aware of what a "Texas Oven" is. If not, its your trunk.

The rounds if left in the vehicle for lengths of time could heat up during the day in sunlight and cool off in the evening/night. The worst this would do is accelerate the powder and primer decay. This would take a significant amount of time, but would lead to less reliablity of your ammo.

Answer 4

Ammunition has to be exposed to heat in excess of 400 degree's or hotter for and combustion to take place.Take the Iraq war for example..military ammo is subjected to 120 degree's all day every day for extended periods of time.If it doesn't explode there ..it won't here in the states.Just don't throw any in a fire.....

Answer 5

No. Smokeless poweder is only a propellant and not an explosive. A hot car may be hot but if the plastic inside does not melt you have no worries.

Answer 6

Bullets are just inert metal. They won't do anything. If you mean cartridges, they still won't pop, but some, especially those loaded with double-base propellants, may degrade a bit.

Answer 7

No, the autoignition temp. of bullets is 255 degrees. althought I would not want to shoot them if they have been is a baking car all day.

Answer 8

Unlikely.

Answer 9

I was in Iraq a year ago. We had ammo and pyro stored in our Hummers, and we never had any cook-off, and I bet it got hotter there than it is in Texas.

Answer 10

No, they won't go off unless your car catches fire.

And if your car ever DOES catch fire with ammo inside, be sure and warn any firefighters who show up, so they can take precautions to avoid injury to themselves or bystanders.