Storing ammo in vehicles: Is temperature a problem?

[mhanna91]

I want to start a discussion specifically about the long term effects on ammunition that is, say, left in the trunk of a vehicle year round in a climate that is -10F in the winter and 110F in the summer. Ammunition in question would be Lake City XM193. Can anyone with experience comment on whether it could become a problem? Please share your thoughts and concerns.

[Voodoo_Man]

I have left pistol ammo (.45 federal hst) in the trunk of a vehicle throughout the winter (gets to around -2 at lowest and 130F (inside the trunk) - 102F at most outside). Still worked fine...

Don't know about rifle ammo, but I would imagine it would be the same, would like to hear people's experiences as well.

[lunchbox]

This has been covered a couple of times. I believe the heat is more of an issue than cold, if I remember correctly. https://www.m4carbine.net/showthread.php?106713-Do-you-Store-extra-ammo-in-your-vehicle
ETA: I used to be in the "stored car ammo" crowd, now I keep loaded mags in EDC backpack (for what ever weapons I have with me) that gets brought in.

[markm]

I personally don't let heat exposed ammo sit for more than a year. I've burned through 40 smith ammo that had been pretty un-kindly stored in AZ heat... and it ran fine.

Annual rotation is more than conservative in my opinion.

[Jellybean]

This is an interest for me too.
Although we haven't' gotten to those extremes of temp. here in VA...

I wonder also if it makes any difference if you store it in an ammo can, versus just the boxes it comes in?

[mhanna91]

In a perfect world I would have a climate controlled garage to park my vehicle in every day which would ensure that my ammunition (and firearms for that matter) never gets below 50F or above 70F, but unfortunately my vehicle is parked outside. I have considered bringing my ammunition inside at the end of each day but my issues with that are the following:

1) If I ever have to GO NOW, I don't want to be fumbling around trying to load up all my gear.
2) I would be concerned that going from cold/hot to room temperature repeatedly may be as harsh on the ammunition as simply letting it sit in consistently hot or cold conditions.
3) Hauling my gear in and out every day would get old quick.

On the other hand, leaving my ammo in the vehicle and rotating it, say, every 6 months would get expensive. I don't have an unlimited supply of ammo or money.

So, all that being said, what are some opinions on the effects of bringing the ammo inside during extreme hot/extreme cold conditions? Would it be as harmful as simply letting it sit in the hot or cold all day and night? Furthermore, what are some opinions on a prudent rotation schedule? Would once annually be safe/reasonable? Or should it be rotated more frequently?

[MegademiC]

I don't think cold is an issue, heat is more likely to be the problem. When Doc was here, I remember him discussing this and it was recommended to rotate stock once a year for most people. That's what I do.

[vicious_cb]

Heat will degrade the powder and cause pressure spikes. Going from cold to hot quickly can cause condensation inside the case, also not good. Constant cold doesn't do anything.

[MegademiC]

Maybe I'm giving too much credit to manufactures, but with sealed/crimped ammo, id hope it was processed in a dehumidified environment so condensation is not an issue. Obviously reloads and cheap ammo all bets are off. Anyone here have insight regarding this?

[HackerF15E]

Your Uncle Sam stores small arms ammunition in non-climate controlled igloos out in the Nevada desert, amongst other places. It gets blazing hot inside those things.

Normal temperature swings -- even inside the 'greenhouse' of a car -- are not going to have any impact on the performance of the powder or primers.

I don't know how so many folks have become convinced that small arms ammo is so temperature sensitive, but unless you are storing it in a sauna, you're not going to have any issues with it.

[MegademiC]

DocGKR:


Be sure to watch your ammo storage conditions. Temperatures above 150 deg F will degrade the powder and cause pressure spikes. Hint: Think locked metal conex containers in the mid-east, car trunks in the southern U.S., and storage areas near heaters in the northern U.S. Also be cautions of leaving a round in a very hot chamber; besides the obvious danger of a cook-off, the powder can also be damaged by the heat, leading to dramatically increased pressures when the round is eventually fired.