How does cold affect ammo in storage?

[EMP]

I've heard about how large temperature swings can affect ammo by shortening its shelf life. They say you shouldn't store it in a garage for this reason. But what if those temperature swings happen only a couple times a year, and the ammo is below freezing half the time. Specifically, how would ammo be affected if it were buried underground in a moisture-tight container in a northern climate where the temperature gets well below zero at night? I'm hoping the affect wouldn't be too bad since the temperature changes slowly underground. But what about being frozen for so long?

[Eat Beef]

Cold is hard on primers. This is why many cold climate countries such as Russia still use corrosive primers, as they hold up to cold better.

However, do you really think all the armories in all the world use climate controlled storage for their ammo? I've fired ammo that was nearly 100 years old, and I find it very hard to believe it was kept from temperature extremes over it's whole life.

IOW, I don't worry about temperature's effect on ammo. I would be fine with storing it underground (don't know how deep your frostline is, but you'd probably be below it, anyway), so long as moisture wasn't an issue.

[EMP]

IOW, I don't worry about temperature's effect on ammo. I would be fine with storing it underground (don't know how deep your frostline is, but you'd probably be below it, anyway), so long as moisture wasn't an issue.

I don't go all that deep. Maybe about 6 inches or so from the top of the container to ground level. I think the frost line is deeper. The thing is, since being underground the temperature drops and rises much slower, so I thought maybe that would help too. If it were in my garage, the temp could go over 110 in the day in the summer and then back to outside temps of 65 at night--every day. Underground, it wouldn't even get below freezing until it was well below freezing above ground for quite some time, and then would warm very slowly and evenly as Spring came.

I like the idea of having an underground reserve because there's no point in investing alot of money in alot of ammo to be used over decades if it could all get stolen in a single breakin of my home. Besides, if it won't be used for years anyway, it also won't cause an inconvenience by having it buried.

[Aurumag]

...so long as moisture wasn't an issue.

Temperature extremes like you describe are not so bad, and as Eat Beef implied, long term exposure to moisture is the real mitigating issue.

I have fired milsurp .308 ammo that was manufactured in the 70s, and I don't even know what extremes it endured before I got it in 1999, but it was still sealed in battle packs.

I have "improperly" stored that same ammo in extremes from 140 down to 20, unsealed, with some short term exposure to moisture, and it was 100% good up to 1600 rounds.

[jogslvr]

Gradual temp changes no problem. Sudden extremes are killers (think condensation and compression). Best all around storage conditions 55-75 degrees dark and dry. I know from my competition shooting days that cold ammo can change your POI drastically due to slower ignition and burn rate. We'd always put our "for record" ammo in our pockets to warm it on frozen morning shoots. Underground would be great storage but deeper than you are doing.

Also was bad to take ammo out of air condition gun room and subject to high temps in summer. We always carried competition ammo in igloo coolers.

Of course I'm talking about 1/4 inch group accuracy at distance as opposed to hitting big center mass target.

Tom D is the resident authority on custom loaded center fire accuracy. Maybe he'll be along with dos pesos, directly?

[ErrosionOfAccord]

Cold is hard on primers. This is why many cold climate countries such as Russia still use corrosive primers, as they hold up to cold better.

However, do you really think all the armories in all the world use climate controlled storage for their ammo? I've fired ammo that was nearly 100 years old, and I find it very hard to believe it was kept from temperature extremes over it's whole life.

IOW, I don't worry about temperature's effect on ammo. I would be fine with storing it underground (don't know how deep your frostline is, but you'd probably be below it, anyway), so long as moisture wasn't an issue.

I don't want to but, I must disagree. In my experience... I bought a case of 7.62x39 in a wooden box. Simply stated, after a decade of temperature changes the ammo went from 100% reliability to (I'm guessing here) about 90%. The caveat was that mine was never underground and experienced everything from garage conditions to climate control.

[MISRy]

Just cracked a spam can of Chi-Com black tip 7.62x39 that was manufactured in `72 and has been underground since `02. (A friend of mine made a good offer for 500 rounds.) 75 went into a drum to show him what AP means and the rest filled a couple of panic mags. The drum went downrange in an impressive fashion.

[Eat Beef]

I don't want to but, I must disagree. In my experience... I bought a case of 7.62x39 in a wooden box. Simply stated, after a decade of temperature changes the ammo went from 100% reliability to (I'm guessing here) about 90%. The caveat was that mine was never underground and experienced everything from garage conditions to climate control.

What do you think got it, hot or cold? I'm guessing you were in a cold place?

Could you rule out moisture? What about light primer strikes or some other problem with the rifle? What went bad, primers or powder? Both? Would they fire on a second try?

[ErrosionOfAccord]

The firearm is fine. I live in the high desert so it may have been cold or heat but I doubt it was moisture. Primers went bad, no squibs and I did try to fire them again. It was Russian stuff and came in a generic white box of 20 rounds. As I said earlier, no spam can, just a wooden crate that held 1000 rounds.

[TomD]

From an accuracy standpoint, temperature is an important variable because it causes the pressure of the load to vary significantly. Benchrest shooters have to change their load during a match as the temps change. As to the effect of cold on primer reliability, I'm not sure that there is one answer because a fair number of different compounds have been used as the explosive agent in primers and each compound has it's own properties. I would think that military ammo would have primers that were reliable after all sorts of storage situations and time frames. I've recently shot WWII surplus 30-06 ball ammo with no problems at all.

[ttazzman]

I recently was cleaning out old ammo....shot 30-40yr old 12ga in plastic hulls no missfires...no issues...garage stored......that being said my new stuff is climate controlled stored

[Professur]

So ... would you say load it into a gamma pail with O2 absorbers and bury that?

[TomD]

Little known fact: The 40mm guns used on AC130 gunships are the WWII vintage weapons that you see shooting at Japanese kamikazes in the History Chanel. The exact same weapons matter of fact, stripped off the warships and stored when the ships were decommissioned. 40mm Bofors ammo hasn't been manufactured since WWII and all now being used has been stored now at least 66 years since the war ended, and stored in non-conditioned storage areas. Seems to work well enough.