Ammo & Temp Fluctuations

[camper]

I'm fishing for information on what possible problems I might encounter by leaving a loaded firearm in a vehicle. Assume it's secured properly, I'm concerned with the temperature aspect.

Like many I can't take my firearm into work with me, but I can have it in my car. I'm trying to find out what risks/concerns/etc I may have with safety/reliability if the gun is in the vehicle during the day, with temp fluctuations ranging from say 0 to 60 to 13 to 70 to 90+ due to the vehicle changing temperature throughout the day (outside temp & inside temps changing based on driving, cooling/warming off)

Anyone have any good sites to recommend, or simply in the know enough to give an answer?

camper

[Xringshooter]

You should not have any problems with your gun/ammo. If you know it's going to be a hot day, crack the windows to let the heat out. Keep the gun stored as low as possible (on the floorboard with a blanket over it) and it will be fine. The heat rises so being down low the temperature won't be as high. Or store it in the trunk (if driving a car with one), the trunk won't get near as hot as the inside of the car (because of not having all the glass). If a pickup or SUV, keep it on the floor covered up, it will be fine.

That said, if you do this every day in hot weather, I would shoot the ammo that has been in the car for a while every month or so. Powder will degrade after a while from high temps and temp variations so it would be wise to occasionally use it up and put new in the mags/speedloaders/chambers.

Oh, and don't worry about the ammo "cooking off", it would have to get very hot to do this and your vehicle would probably also be a pile of cinders.

[bogey1]

i know some guys put their bullets in their exhaust pipe to heat them up before competition (.50bmg). so i wouldnt worry at all.

[tlgpa]

Considering soldiers in Iraq are carrying ammo in temperatures of 120-130°, I think you'll be ok here in PA.

In this study, with 125° outside temp, the inside temp was 159°.
http://www.mydogiscool.com/x_car_study.php

I found this online

In his book "Gunshot Wounds" Vincent Di Maio describes various experiments where ammunition was heated in ovens. He says that .22 long rifle cartridges detonate at an average of 275F, .38 Special at 290F and 12 gauge shotgun shells at 387F. The interesting thing about these furnace experiments was that in all instances the cartridge cases ruptured, but the primers did not detonate. In fact the primers were removed from some of the ruptured cases, reloaded into other brass and fired.

When cartridges are placed in a fire he confirms that the most dangerous component of a cartridge is the brass, or fragments thereof that may cause eye injury or penetrate skin, but certainly there is no evidence that a cartridge that is not in a firearm can cause a mortal wound, either by action of the bullet or the brass/primer fragments. It is important to remember however that a chambered cartridge that detonates in a fire is just as dangerous as a cartridge that is fired under normal circumstances in a firearm.

To get a better understanding of the behaviour of free-standing ammunition in a fire, he conducted experiments with a propane torch. A total of 202 cartridges (handgun, centerfire rifle and shotgun cartridges) were used. If the heat was applied directly to the base of a shotgun shell the primer would detonate, the powder would ignite and the shell would rupture. Any pellets that emerged were traveling too slowly to be recorded on a chronograph.

In rifle and handgun cartridges where the flame was applied to the base of the cartridge the primers always detonated but the powder only ignited in half the cases and in those instances the cases did not rupture but the gas was instead vented through the primer hole.

When he heated these same handgun and rifle cartridges at the front, the powder would burn and the cases would usually rupture but with few exceptions the primers did not detonate. The velocity of expelled projectiles ranged from 58 ft/s to 123 ft/s. The only exception was the .270 cartridge where the bullet velocity was 230 ft/s. Primer velocities ranged from 180 ft/s to 830 ft/s.

As a side note he says that a revolver in a fire is especially dangerous because all the cartridges can cook off and be discharged such that there is a danger from projectiles. Only the bullet that came out of the barrel will have rifling marks and the ones that came from non-aligned chambers will have shear marks on them. Obviously if there is a question about the firing of a weapon and whether it was cooked off or fired intentionally they will look for a firing-pin impression on the primer of the suspect cartridge case.

References:

Sciuchetti G.D. Ammunition and fire. American Rifleman 144(3): 36-38, 59-60, March 1996.

Cooking-Off Cartridges. NRA Illustrated Reloading Handbook. Washington, D.C.: The National Rifle Association of America.

And of course Vincent Di Maio's excellent book "Gunshot Wounds - practical aspects of firearms, ballistics and forensic technics". My copy is the second edition, published by CRC Press, ISBN 0-8493-8163-0
This information can be found on pages 268-270.

[camper]

I'm not worried about the ammo cooking off at all, my concern is more in line with possible moisture due to the changes in temp.

- At 6am I bring the ammo from a house temp of 68 to a car temp of 10.
- Car warms up to about 70 by the time get to work.
- Outside temp is now 20.
- Around noon I head to lunch, temp is 34.
- Car gets to about 70 by the time I get back to the office.
- Outside temp is still 34.
- By mid afternoon it's a balmy 48.
- Drops down to 30 by the time I leave.
- Car warms back up to about 70 by the time I'm home, walk the gun into a house of about 68.

And then there are the days where it's rainy/snowy or out and out muggy. Summer would be similar, but higher fluctuations in temp due to internal heat of the car getting hotter and the car reaching a cooler internal temp.

I expect that the gun and bullets are going to 'sweat' a little due to the fluctuating temps, much like any other piece of metal you would leave in your car under similar circumstances. And while I don't want the gun or ammo to be ruined, my MAIN concern is that the round won't fire when needed if the powder is compromised.

I realize I could be over-thinking, but want to be safe rather than sorry

camper

[galvanni]

I have the same exact concerns as you - same routine too. Like you, I don't care about anything other than the thing still goes bang when I need it to.

[RobW]

Nah, guns and bullets don't "sweat" moisture, they don't contain any. They will gather condensation if you go from cold/dry to warm/damp. Keep them in a case, no worries at all. You are overthinking this a bit ;->

I'm not worried about the ammo cooking off at all, my concern is more in line with possible moisture due to the changes in temp.

- At 6am I bring the ammo from a house temp of 68 to a car temp of 10.
- Car warms up to about 70 by the time get to work.
- Outside temp is now 20.
- Around noon I head to lunch, temp is 34.
- Car gets to about 70 by the time I get back to the office.
- Outside temp is still 34.
- By mid afternoon it's a balmy 48.
- Drops down to 30 by the time I leave.
- Car warms back up to about 70 by the time I'm home, walk the gun into a house of about 68.

And then there are the days where it's rainy/snowy or out and out muggy. Summer would be similar, but higher fluctuations in temp due to internal heat of the car getting hotter and the car reaching a cooler internal temp.

I expect that the gun and bullets are going to 'sweat' a little due to the fluctuating temps, much like any other piece of metal you would leave in your car under similar circumstances. And while I don't want the gun or ammo to be ruined, my MAIN concern is that the round won't fire when needed if the powder is compromised.

I realize I could be over-thinking, but want to be safe rather than sorry

camper

[Xringshooter]

The inside of the bullet won't sweat anything, there's no moisture in there (or at least there shouldn't be) they're pretty well sealed from moisture when every is put together, even with reloads. Now coming into a nice warm camp after a days deer hunting in cold and snowy (or rainy) weather, they can get some condensation on them but that is only on the outside. You wipe them off and they warm up and dry off.

[Grillman]

I can't take my gun into work. I keep it in the console of my vehicle. I have
been doing this for years.Sometimes for days with no problems.I do crack
the windows a little bit when hot out.