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10/20/2017 1:01:18 AM
9/22/2017 12:11:25 AM
Posted: 8/1/2005 11:32:14 AM EDT
Here in North Texas, it is common for the temperature inside a vehicle to exceed 160 degrees F during daylight hours for a good part of the year. I would like to keep an AR15 in my vehicle for a number of reasons. However, I am concerned that this may have some negative effect on ammunition performance and useful life, if not actually affect the rifle's operation, should it be needed. On the other hand, I know that weapons and ammunition currently deployed in places like Iraq (like my Marine son's) must be subjected to similar conditions.

Should I be concerned? Are there any precautions I should take when keeping a weapon in such an environment? Thanks...

7.62

Link Posted: 8/1/2005 11:36:21 AM EDT
Link Posted: 8/1/2005 12:02:33 PM EDT
Make sure you put a dessicant packet in there and monitor it routinely.
One of my coworkers kept an AR as a trunk gun in his Lexus, and he had surface rust on it from the humidity. (DFW)
Link Posted: 8/1/2005 12:44:52 PM EDT
[Last Edit: 8/1/2005 12:45:39 PM EDT by Spooky130]
I read on the 10-8 forums about LE types in Texas having issues with blowing primers in M14s after leaving the ammo in the trunk of their cruisers. I think it was partially the fault of the ammo - American Eagle - because the primers aren't staked in place. That being said, blowing primers out is not a good thing.

I'll be watching this to see what folks say because I'm now in Texas myself.

Spooky
Link Posted: 8/1/2005 1:06:23 PM EDT

Originally Posted By Spooky130:
I think it was partially the fault of the ammo - American Eagle - because the primers aren't staked in place.
Spooky



The primers blew out because the ammo was left to overheat under conditions that led to an abnormal increase in pressure. Staking primers might have kept them in, then what? What else could give way? Case head ruptures are not uncommon in overpressure situations.

ALL gunpowders create more pressure when they are overheated. Some do it more than others. Ball powders are, as a group, the most thermally unstable propellants.

In all honesty, I don't know how to keep ammo temps at a sane level when stored all day in a car in the Texas sun. Maybe put a thermometer in the trunk and one in the cabin, leave the car in the sun for a few hours, then read them both and see which is cooler, and by how much.
Link Posted: 8/1/2005 1:19:31 PM EDT
[Last Edit: 8/1/2005 1:20:10 PM EDT by Spooky130]

Originally Posted By SWO_daddy:

Originally Posted By Spooky130:
I think it was partially the fault of the ammo - American Eagle - because the primers aren't staked in place.
Spooky



The primers blew out because the ammo was left to overheat under conditions that led to an abnormal increase in pressure. Staking primers might have kept them in, then what? What else could give way? Case head ruptures are not uncommon in overpressure situations.

ALL gunpowders create more pressure when they are overheated. Some do it more than others. Ball powders are, as a group, the most thermally unstable propellants.

In all honesty, I don't know how to keep ammo temps at a sane level when stored all day in a car in the Texas sun. Maybe put a thermometer in the trunk and one in the cabin, leave the car in the sun for a few hours, then read them both and see which is cooler, and by how much.



Honestly, that's what I was thinking too. If the pressure can't go out around the primer where is it going to get out? Any thoughts on this scenario:

Three mags down the tube as fast as F/A or your finger will allow. You change the last mag with one left in the chamber and say, you go back to a bench to reload your three mags. That round is in a very hot chamber - that has to have some effect - thoughts or experiences with this one?

I guess the other question is: how are the USGIs storing their ammo in the desert. It is damn hot over there too...

Spooky
Link Posted: 8/1/2005 2:31:50 PM EDT
Spooky, that last round left in a hot chamber will do one of two things. At best it will just end up higher on the target for the same point of aim (high pressure = higher velocity = less drop). At worst it will cook off on its own.
Link Posted: 8/1/2005 3:51:16 PM EDT
I have kept ARs and AKs in the trunk every day for years now and never any any issue of any sort. You will want a Magpul or fixed stock though because if you put your cheek on a 150 degree buffer tube you will not be happy.
Link Posted: 8/1/2005 6:01:42 PM EDT
Parking in the shade whenever possible can make a HUGE difference.
Link Posted: 8/1/2005 6:08:14 PM EDT
tint the windows?
Link Posted: 8/1/2005 6:16:21 PM EDT
Make sure that it's clean. After some 90 rounds of Wolf (which is a bit dirtier than most), I let if sit in the car for a week or so (AZ summer). I went to pull the charging handle, but the bolt was stuck closed.

I had pivoted the upper to cock the hammer (which was in the "fallen" position) so I could dry-fire it to loosen things up.
Link Posted: 8/1/2005 6:37:21 PM EDT
When I was in TX, I kept firearms in the truck regularly, with no problems. Even in the heat of summer. I now live in the desert of Eastern Oregon. Contrary to popular opinion elsewhere, it does get HOT here. It's been over 100 degrees for the last two weeks, and we are at 4500-7000ft in elevation. I keep a .30-06, and a .22 in the truck at all times, on the back seat. It is exposed to direct sunlight through the windows for lengthy periods of time. I've never had a problem with it. Could be luck, could be keeping my weapons cleaned, or it could be that there's not an issue in it.

When I did work for Uncle Sugar back in the day, we had our weapons out in the desert and in the swamps in 100 degree plus weather, with no problems.

Link Posted: 8/1/2005 7:13:20 PM EDT
you guys in texas got it made we can't have crap in our cars in michigan
Link Posted: 8/1/2005 9:36:54 PM EDT

Originally Posted By SWO_daddy:
Spooky, that last round left in a hot chamber will do one of two things. At best it will just end up higher on the target for the same point of aim (high pressure = higher velocity = less drop). At worst it will cook off on its own.



I can see the change in point of aim, but I don't think it would get hot enough to cook off a round. In my part of Florida, the biggest problems are humidity and salinity. It doesn't take long to rust up a trunk gun if you're not careful.
Link Posted: 8/1/2005 9:40:27 PM EDT
[Last Edit: 8/2/2005 12:29:29 PM EDT by Lumpy196]
Never had ammo stored in the trunk for long term fail to fire or not perform as expected.
Link Posted: 8/2/2005 3:11:00 AM EDT
im starting to do the same with my rifle

i have dark tinted windows and leave them cracked open a bit with safe/possible.

but then again i work graveyard shift so im asleep in the day time and usually bring it in with me
Link Posted: 8/2/2005 8:27:37 AM EDT
[Last Edit: 8/2/2005 8:28:04 AM EDT by 308win]
I'm thinking that if I keep it clean, and be sure to cycle the ammo through every month or so (another excuse to go to the range), the only issues I may have is a burned cheek or an elevated point-of-impact. So, now I will move on to finding the best, discreet mount for the AR. I would like a ceiling mount, but will probably end up with something behind the rear bench seat in my crew cab P/U. Thanks all...

308WIN
Link Posted: 8/2/2005 10:01:59 AM EDT

Originally Posted By 308win:
I'm thinking that if I keep it clean, and be sure to cycle the ammo through every month or so (another excuse to go to the range), the only issues I may have is a burned cheek or an elevated point-of-impact. So, now I will move on to finding the best, discreet mount for the AR. I would like a ceiling mount, but will probably end up with something behind the rear bench seat in my crew cab P/U. Thanks all...

308WIN


Lots of weapons and ammo are being stored in hot vehicles now throughout the ME. I've carried ARs, shotties, and pistols (with significant amounts of ammo) parked in my POV all day with no AC or shade while on duty in the North and East Texas sun and never had a problem. Some ammo will degrade/become unstable if left in heat for a long period of time. Just rotate your ammo and don't keep your entire stash in the truck. One of the jokes in our old department was that you could smell the gun oil in the parking lot as you pulled in, and the Chief honeslty used to worry about heat-induced detonation in our POVs.
I know sometimes (particularly in the ME) weapons that are in the sun for too long are so hot that you literally cannot touch them without gloves. No detonations there, so I wouldn't worry too much about that here. Just rotate your ammo.
Link Posted: 8/2/2005 12:20:30 PM EDT

Originally Posted By Lumpy196:
Never had ammo stored in the truck for long term fail to fire or not perform as expected.



Same here in Texas.
As LEO we leave patrol rifles in the trunk until they are deployed. Just keep it clean and oiled. We rotate ammo every six months with no problems thus far.
Although I would like to see chrono numbers on some of the ammo that was exposed to the heat for several months.

BTW, our range ammo is stored in a portable storage building at our range. Some of that ammo may sit for several months. The storage building ranges in temp from 70 dregees to well over 100 degrees. We have not had any problems with the Win white box ammo we use for quals, other than the seldom FTF form light primer strikes.

All this aside, I do not to leave my pistol duty ammo exposed to extreme heat or extreme temp changes.
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