Like most of us here I keep a glove box gun in my car along with some ammo. My question is how often do you cycle out your car/BOV ammo? I know that cool and dry is optimal and car interiors do get very hot. Won't last long in that kind of heat. So,what do you do?
Semi-anually. I switch carry weapons dependent upon the current temperature ranges. eg: It's hotter than the dickens in the summer with humidity approaching 100% this time of year. So the heaviest cover garment I can get by with is a golf shirt, so it's my Kimber Micro in .380. Come October I'll switch over to an XDm in 9mm, and the vehicles ammo stash adjusts accordingly.
I don't think the extreme temperature fluctuations in a vehicle have a significant effect on ammo going bang on demand without a span of decades. I'm not going to fight data that says bullet velocities could vary beyond tolerable limits for long range accuracy. Something like that may be true. I have no idea. However, stray 22 LR (rumored to be the most susceptible ammo to degradation) under an old floor mat, in a glove box, or in a crossbed toolbox has always functioned fine for a turtle massacre or kill a snake in the chicken coop.
My results are the same as Zimmy. Lots of the corrosive surplus stuff I shoot from the 1930's is still good as new. I'm sure some of it was stored in hot climates. My opinion has always been that any military ammunition manufacturer who's ammo failed to function after it got hot or cold was likely to be hunted down by the survivors of that battle, and killed. I have never had a box of ammo that wouldn't go bang after years of trunk travel. Even on the range, where milliions (?) of rounds.are expended annually, I have only ever found two boxes of ammo where none would fire. One was .30-06, handloads with no powder. The other was GI surplus .38 Special that was completely corroded blue. This stuff may have fired, we didn't try. It was dumped in the brass bucket. I'd love to have had some history on the stuff. I have .22 Thunderbolt from 1971 that I found in a box in the barn. Minimum of 10 years with no climate control. Shoots better than lots of new .22 ammo. I'm confident that my storage is dry. That alone seems to be the biggest factor in ammunition longevity. YMMV.
I load and unload my rig daily, so none of this is an issue for me! I also swap rigs often so it has to be this way!
If there is any degradation it is the composition or manufacture of the ammo, I do not have any wax coated / lubed 22's for a reason wax melts. fired extensively in a single session the innards of your shooter is going to be very nasty. if you have such ammo in the paste board boxes know that half is positioned up and the other half nose down if they get hot the wax may reduce the power of the load even if it in by a minor degree it will cause shot stringing. Any ammo stored in less than optimal conditions needs to be mil spec with a sealed bullet & primer. Heat and extreme cold effects most all powder with a possible hang fire or high pressures effects accuracy and ballistics. This is easily proven leave one box in full summer sun the other keep in the shade fire 5 shot groups in different targets with the different temps of ammo. Not that commercial is unable to handle storage at extreme temperatures but newer powders and techniques are better.. I am not worried about any ammo made after 1955 foreign ammo made after 1960, the effects of cold heat temp wind and humidity and temps of the ammunition as it's being used at the moment of firing is vastly more important than the storage in a sealed can or battle packs that said I would be more concerned with heat from a box of ammo being left on the dash or in a rack in open sunshine and external conditions at the time I fire it as it is all relative. http://www.longrangebpcr.com/Accuracy.htm exterior ballistics Firearms History, Technology & Development: The Effect of Temperature on Ammunition Performance http://riflebarrels.com/ballistic-effects-of-altitude-temperature-and-humidity/
Long gun ammo is US mil sealed battle packs. I do not worry about them and they seldom get swapped out. I only store CCI Stingers vac sealed for bug out bags/BOV. Handgun ammo is my reloads that again are vac sealed. Since I've shot my reloads that were over 20 yrs old with no failures I don't worry too much about my ammo.
The only reason to have spare ammo along is if the car died (EMP/CME) and I'm on foot. In which case what is in my EDC bag is all I carry . I have been in situations were the only place provided to park is under a bridge or in a parking garage in which case either it may be crushed or too many others are milling around to take the chance recovering gear . Any proximity to freeways and hoards of folk looking for help will be flooding the area. Any cataclysmic event I am forced on foot , my first priority is get water in my containers then head home, IF that is an option . Depending on how far from home I am, it can take hours to weeks depending on the distance, time of day, weather, the main event and micro events along the way. If it takes several days to get home, it is more likely that the need for the gun be vital for survival. Especially after reaching home and invasion has taken place. I don't expect ammo to go bad in a container unless there is some rattling around. Cotton can take care of that and be useful for other things . Knowing how much ammo is impossible . Cops can burn several hundred rounds in a fire fight or only a handful . I grew up having a very limited supply of ammo, so I learned to make my shots count even in a stress event . But kids that had no discipline and an unlimited supply of ammo burned it up like it was free and wasted a lot of ammo . Cops with poor training rarely hit the person shooting back at them. Not discounting the value of semiauto, but those with them tend to waste ammo. Post SHTF there won't be shops to replace the spent ammo . And bad habits die hard ,especially in/after a fire fight. It ain't no video game.
