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Extreme heat & extreme cold effect on ammo?

Discussion in 'Handguns: General Discussion' started by Alan Fud, Jan 2, 2013.

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  1. Alan Fud

    Alan Fud Member

    Dec 24, 2002
    I'm thinking about keep a spare gun in my car in a bolted down strong box. However, I'm concerned about how the reliability of the ammo might be effected when exposed to sub-freezing temps in the winter and 100+ degrees in the summer. Thoughts? Ideas?
  2. thefish

    thefish Member

    Feb 17, 2012
    I'm actually intrested in this too.

    I've been meaning to post a similar question.

    Specifically, if gun is brought inside from say 5 below to room temp, is condensation inside the ammo possible, and problematic?
  3. rcmodel

    rcmodel Member in memoriam

    Sep 17, 2007
    Eastern KS
    No problem.

    How many rounds of ammo & how many guns do you think cops keep in the trunk of a police cruiser in Death Valley AZ, or Nome Alaska year round?
    Or say those GI's in Afghanistan or Iraq riding around in a 140 degree Humvee?

    Rotate the ammo out occasionally and use them for practice and you will be fine.

    I have .22 & .40 S&W ammo in my truck console that has been in there for years here in Kansas.

    Below zero and above 110 every year.
    When it isn't 85 in the day and 35 at night.

    It all works when I shoot it up and replace it when I get a Round Tuit.

    Condensation when bringing a gun inside from winter conditions?

    Warm it up immediately by laying it on a furnace vent or something.
    Then wipe it down once it reaches room temperature.

    The condensation won't hurt the ammo, but it sure will rust a gun shut if you leave it to it's own devices.

  4. Lucky Derby

    Lucky Derby Member

    Aug 23, 2006
    Colorado Rockies
    Reminds of a story I read several years back about a police officer in a cold climate who had been working traffic enforcement. He had been getting in and out of a nice warm patrol car all day to write traffic tickets. Late in his shift, the driver of the car he had stopped decided he wanted to shoot at the officer. When the officer tried to return fire he could not pull the trigger on his S&W Sigma (early Glock style Sigma). The firing pin had rusted into place from condensation. The officer was able to get the 870 from inside the patrol car and shot and killed his attacker with the shotgun.
    I read this in a gun rag quite a few years back. I always though it was probably more than one shift's worth of condensation.

    MDW GUNS Member

    Mar 6, 2004
    Maine USA
    I am sure everyone heard of "cock off" rounds.
    That happens when a hot gun is so hot that the powder in the primer will ignite.
    These temperatures however will not be reached in a vehicle.
    On the other extreme, cold has no effect on powder or primers short term.
    Short term in that case still means several years.
    If ammo is subjected to large temperature changes over years, the powder will loose it's burning characteristics; it will get weaker.
    One reason you should use your oldest ammo up first and not leave it in the vehicle for a decade and wonder why it did not work right.
  6. Bushpilot

    Bushpilot Member

    Mar 28, 2011
    There are more misfires in cold temps than in warm. Primers are less sensitive in the cold. It's not unusual for a handgun that has had the hammer spring lightened too much during a poor trigger job to work OK in the summer and then have misfires in the winter, after it and the ammo are cold soaked. As long as you use a gun with a strong primer strike you won't have a problem.
    Last edited: Jan 3, 2013
  7. jmr40

    jmr40 Member

    May 26, 2007

    Extreme temperature could have an effect on the ammo. It depends on the powder used. The military specs. call for powder that is specifically formulated to be stable in a wide variety of temperatures. That is why they can use it at 140 degrees in the desert and also at -40 in the arctic.

    If the powder in your your ammo is not made specifically to be temperature resistant you could easily create a situation where a load fired at 70 degrees is just fine. That ammo setting inside an enclosed car in a hot environment could be well over 150 degrees. Fired at that temperature and it could be a dangerous over pressure load. You can see 100 fps more speed between a round fired at 20 degrees vs 100 degrees with some powder. If you load your own ammo and know what type of powder you are using you can choose specific powders that are resistant to temperature changes. But with factory loads you don't know what you are getting.

    Not really much danger at colder temps, but in extreme cold a rifles POI can change dramatically because of temperature changes, especally at longer ranges.

    If the ammo gets extremely hot, or cold, it isn't permanately damaged. When it returns to a normal temperature it will work just as it is designed to.
  8. Shadow 7D

    Shadow 7D Member

    Nov 30, 2008
    Frozen North
    Having shot 'military' ammo in the high negatives
    I can tell you it DOES NOT behave the same as when it's warm out
    the POI is off (check out mirage for part of why, also the EXTREME difference between cold shot and hot shots)

    but the best part was the
  9. pendennis

    pendennis Member

    Aug 6, 2011
    We have bench rest shooters at our club who keep their loaded ammo in coolers until their next relay. I asked them, and they said that hot weather, more than cold has an effect on the performance of their ammo. Evidently double-base powders are affected more than single-base.

    I shoot a lot of trap and skeet, and the velocity is somewhat lower in very cold weather than warm.

    And changes in temperature seem to have an effect over time; not necessarily incidentally.
  10. Drail

    Drail Member

    Jan 17, 2008
    A lot of competition shooters will keep their ammo in a cooler when shooting in high temteratures because it can affect the burning speed of some powders which can throw fine accuracy out the window.
  11. PO2Hammer

    PO2Hammer Member

    Nov 30, 2003
    I've shot a lot of ammo kept in sub-zero temps, no troubles, but I don't leave the same ammo in my car month after month.
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