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Long Term Bulk Ammo Storage
I am making some large ammo purchases this year, and I generally store it indoors, yet some of the locations I use are not heated, and may get as cold as - 20, and as warm as 80. I store most ammo in ammo cans, some in battle packs as well.

Does anyone have any experience with this? I have heard both positive and negative things, but the ammo i pull from storage always shoots fine.

I have some in my truck that gets the warm/cool treatment nearly daily, but shoots just fine. I would expect WWII military history reflects this, but i could be wrong.

Any ideas?
The most dangerous enemy of modern ammo is MOISTURE. I've had various rimfire and centerfire ammo stored in areas where it got down to about -10*F, and up to 120*F, and never had one problem with it.

When I lived in Los Angeles, I reloaded centerfire rifle ammo when it was 100*F, and the shot it at 13,000 feet altitude, -8*F, in Colorado, and my zero didn't change. The elk tasted mighty good, too!

Main thing is to keep your ammo free of moisture. Use the silica packs, or equivalent, if you're storing it.

Good luck. L.W.
"Always go straight forward, and if you meet the devil, cut him in two and go between the pieces." (William Sturgis, captain, clipper ship, 1830s.)
Yep, I have 12 military ammo cans filled with a variety of ammo (pistol, rifle, shotgun, rimfire, centerfire). I have silica packs in every single can. No issues at all with any of this ammo.
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sounds like i am on the right track then. I have been fairly anal about my ammo.

I just did not want, say, my 30,000 rounds of 22 lr to be duds in five years!!

Thanks guys!
I had six bricks of .22 I put in about 6 years ago. I have slowly shot through 1 full brick and no problems.

Just make sure the rubber seal in the top of the milspec ammo can is good. A tight seal surely helps.
"A Nation of Sheep will beget a government of wolves." Edward R. Murrow

"Bring me a GREEN one, I'll scrub the patchoulli off her!" Ghostwolf.
I have some 20 gauge shells that I inherited that are close to 30 yo, and so far no problems. Also have some .22's from the 60's and 70's that still have plenty of pop. My grandad stored them all in ammo cans. The only rounds that I've had problems with were some that I got from my dad and some surplus rounds that were part of a curio rifle deal. MY dad just left them on a closet shelf and I've noticed a slight decrease in realiability. Had a varmint in my sites a few years back and none of the 10 loaded rounds fired. I kept cycling the action myself, while stalking after it till I was out of rounds. Varmint got away. Call me the world's worst hunter. As far as the surplus, it's from the 50's. None of the rounds I've fired performed incorrectly, but I've had to sort through them before hand to discard any that showed flaws.
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Bye, Everybody. And thanks for everything.
There was an article in Precision Shooting about a year and a half ago. They noted that for real serious accuracy work, you may have POI change. This is due to adhesion between the case neck and the bullet jacket. They also noted that you might get a few FPS drift with some powders but MIL type will survive temperature changes well, by design. For general use, this should not be a noticeable issue. Let’s see if –ML has anything else to add.

…Keep your powder dry!

Where have I heard that before…

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First of all, I'd like to suggest to one of the moderators that this entire thread get moved over to the Weapons section, where I think it is more appropriate.

This question of ammunition storage is a good one. Thankfully, there’s been some good research done as well. Here’s the short version: Modern fixed ammunition has two primary enemies: heat and moisture. Of the two, moisture is generally the more damaging. Cold alone appears to do relatively little permanent damage to ammunition, although cold conditions often involve moisture (including condensation within the cartridge itself), so other than in a laboratory, it’s difficult to comment on cold without addressing moisture as well. The most vulnerable part of a fixed cartridge is the primer, although extreme temperature swings can affect the burning rate of certain powders (more on that in a minute).

The Bad News: Improper storage of all that ammunition you’ve horded can make it worthless.

The Good News: Modern ammunition produced in the United States is incredibly well-made, and when stored under proper conditions one could easily expect a shelf life of 50 years, or even double that.

The Bad News: You probably haven’t stored your ammunition in an ideal fashion.

The Good News: Ammunition made in WWII is routinely available, and most of it at least ignites just fine (more about this point later as well). This stuff generally wasn’t made as well as modern US-manufactured ammunition, and it’s still functioning sixty years later.

The Bad News: If you’re buying surplus ammunition, you often have little idea how old it is, and virtually no idea under what conditions it was stored.

The Good News: If you adhere to the precepts of ammunition storage outlined here, you’ll die of an infarction long before your ammunition goes bad. Which means after you croak, when I swoop down on your estate sale and buy up all of your carefully hoarded ammo for five cents on the dollar, I’ll be getting the deal of the century.

* * * * *


Modern ammunition is really just a cocktail of chemical compositions, and as with most chemical reactions, heat speeds them up and cold slows them down. This is especially true of degradation. What this means is that primers stored in hot (120-degree F-plus) environments pretty consistently show a breakdown of the priming compound, sometimes after as little as a year. Sure, it may be butt-freezing cold in your little slice of the world on this January morning, but 120 degrees isn’t as uncommon as you think, especially since we’re not talking about 120 degrees outside air temperature, but 120 degrees where the ammunition is stored—think hot car trunk, an uninsulated attic or warehouse, or a steel shipping container sitting on a flatcar for a couple of months or a railroad spur in the southwest. (Not an uncommon occurrence—manufacturers know that renting a flatcar and parking it on an unused section of track is a lot cheaper than renting warehouse space.) Reports from Iraq show some relatively serious degradation of 5.56 x 45 ammunition in less than a year. It’s easy to see a quantity of this making its way back to the States and finding its way onto the market, too.

As noted, extreme cold per se appears to have a relatively small deleterious effect on ammunition, but the concomitant moisture does. Ammunition fired while it is very cold often ignites perfectly, but shows a not-insignificant drop in velocity. Ammunition merely stored in a cold environment and fired in a normal temperature typically reverts to its standard velocity

Tropical conditions are another story, and probably the most deleterious in terms of ammunition storage. As air temperature rises, the ability of that same air to hold moisture also rises—that’s why it’s so humid in Panama during the summer, but so dry on a 14,000-foot Colorado peak in December. So, under tropical conditions, you have both high heat and potentially high moisture.

As noted, most modern propellants uses in the US are relatively temperature stable in terms of performance, but this is not always true, and certainly wasn’t in the past. When the British were loading cartridges with Cordite in the fin de siècle period when the sun never set on their empire (cue the Bonzo Dog Band’s Hunting Tigers Out In Indiah), those rounds would produce a much higher pressure in hot, tropical conditions. This became a real concern when a rifle was chambered for something like the .375 Holland and Holland Magnum, or one of the British .400 or .500 big bores. A “tropical” rifle was built extra-strong to handle the loads; today, Ruger still offers a “Tropical” in their magnum Model 77 lineup. “I say, J.O., jolly good!”


This is much easier to understand. It destroys primers, and corrodes brass. Under severe conditions, it may even compromise the powder. All bad. This doesn’t have to be standing water, either; just think humidity over 60 percent.

Ideal storage:

Thankfully, both the NRA and the military, as well as the ammunition companies, have done a lot of research here, and it’s pretty accessible. A year and a half ago, I cited some test on the subject, which I’ll reproduce here; it’s really the best-case scenario:

The method the military and ammunition industry use for long-term storage of ammunition is very old and very simple. Make a concrete bunker with walls about a foot thick. Then cover the whole thing about a yard deep with dirt. This construction is called an "igloo." The igloo produces a remarkably constancy in temperature and humidity inside, requiring neither power nor adjustment. Using this technique, modern small-arms ammo may be stored for 40 or more years with no material degradation. Conversely, ammo "stored" in a hot car trunk may be dead as a mackerel, or wildly inconsistent in a single summer. However, not all of us have an "igloo" handy. Given even moderately consistent conditions most modern ammunition components are fairly resistant to degradation in the short run, say 10-15 years, absent high temperatures and/or constant temperature fluctuations.

To hit the high points of home storage very generally

1. In general, it is the PRIMER that you are worried about. Absent excessive high temperature and/or humidity, modern smokeless powder is very resistant to degradation in storage. As an interesting aside, corrosive priming compounds commonly in use have longer storage lives and are more resistant to degradation than comparable non-corrosive priming compounds.

2. No matter where you store ensure there is "dunnage" (i.e. 2x wood) under and between each layer stacked. Also ensure there is air space between stacked cases on the same layer. These provide air circulation, which is crucial.

3. Humidity--Drier is better, but in sealed cans will make little difference if dunnage and air space are maintained. The ammunition should be packed with a desiccant. You can purchase a commercial product or go the "do-it-yourself" route. Go to any construction site and ask the straw boss if there are any broken sheet rock boards around or some wallboard scraps. There will usually be. Sheet rock is gypsum and hydroscopic. Get a few pieces and cut them to about the size of a deck of cards square. Cook them in the oven at about 200 degrees for a few hours to drive the moisture out of them, then put one in each of your ammo cans. The piece will absorb what little moisture there may be in your ammo can giving you a nice dry environment.

4. Temperature--This is a big one with lots of details. Good ammo is like good wine. Both like a constant, even temperature around 65 degrees F. The constancy of temperature is more important than the temperature itself. (This is a dandy excuse to build a wine cellar to store both.), And, as a wise man once said, "you can never have too much of either."

For short-term storage of general-usage ammunition, the most important factor is to keep the ammo out of excessive heat--say over 85 degrees. Excessive heat degrades ammunition. Ammo stored in car trunks is the most common victim here. Low temperatures do not harm ammunition per se. What degradation may occur is caused more by repeated temperature fluctuation than by the cold. (As an aside, double base powders can perform erratically when USED in very cold temperatures, but this is not a function of storage.)

At this point we probably should explain what we mean by "degradation" If you're storing MG ammo or "rattle battle" ammo, for a few years, the garage should suffice nicely, given the constraints above. The standard deviation of the velocity may go up slightly, but I suspect you will not notice a thing. On the other hand, if you are storing match ammunition, I'd recommend keeping the stuff in a place with a more even temperature. The bedroom closet, where the temperature stays nice all year, for instance. With something as precise as match ammunition even a little degradation could be of consequence.

Invest in a "min/max" thermometer that shows both the minimum and maximum temperature recorded. They run 10 bucks or so. Check your storage area monthly for signs of excessive temperature (check the min/max) or other degradation (rust on cans, etc.). There are no magic procedures. Just remember that equipment respected is equipment that will be reliable.

(End citation)

We’ve had some posters note that they’ve shot ammunition that was (fill in the blank) years old, and it worked just fine. Well, I guess that depends on what your definition of “fine” is. If all you want it to do is go bang and leave the barrel, yeah, I’m sure it did that. But was it accurate, did it show velocity that was too high or exceptionally low, did it function adequately in an autoloader with a gas system? Old, improperly stored ammunition may still go off, but also become compromised. Better to store it properly, and rotate your stock.

* * * * *

Okay—you’ve been good little children and listened to the lecture; now it’s story time.

Story Number One:

Several years ago in Germany, I was visiting a relative who’s 90 years old now. Let’s call him Uncle K, though he’s neither my uncle, nor does his name start with that letter. In the Second World War, he fought in a rather well-known Gebirgsjäger unit, the German mountain troops, from 1938 through 1945. One day he dragged me down to his basement to show me something.

It was his old Kar98k Mauser, brought home at the end of the war and concealed for the last 60 years, along with a couple hundred rounds of ammunition still in his original, leather ammunition pouches and his belt, bayonet, canteen, a Walther P.38 pistol and his tricouni-nailed mountain-climbing boots. When I last visited, the rifle was immaculately maintained, freshly oiled, and without a spec of rust. I asked him how he got the thing home, when the army had to surrender its arms. His sharp, clear, blue eyes narrowed. “That rifle kept me alive for seven years in the infantry, in France and Italy and Russia,” he told me in impeccable, clipped German. “I wasn’t going to turn it in. And I still know how to use it.”

No doubt. His kids, now in their 60s themselves, knew nothing about it. He was no crazy Nazi still fighting the war, either—quite the opposite, in fact. Just a tough, independent old goat who didn’t trust any government. I traded him for ten of the cartridges and brought them back home.

I’ve got plenty of 8x57 Mausers of my own, but I thought these shells were special, so I arranged to fire them through another Mauser from WWII, this one brought home as a war trophy by my late Uncle Fred, who, along with my father and another brother, were in the U.S. military. (The irony that 60 years ago Uncle Fred was probably dropping bombs from his B-17 on Uncle K. isn’t lost on either of them.)

Every single one of those ten rounds performed perfectly. While we didn’t fire them over a chronograph, we did fire them on a paper target, and the group size was no larger than I could get from that same rifle with modern commercial ammunition. Uncle K knew how to store his material. Aged 90, he’s still good to go.

Story Number Two:

I have another German “Uncle,” who was 15 when the war ended, and is 75 now. Right in the closing days, one of his relatives, a Wehrmacht infantryman retreating from the Russian front, gave him a revolver. “I don’t know what’s going to happen when this war ends, but you may need this.” True thing! The 15-year-old, on his own in a defeated country, knew he should hang on to the gun, but didn’t want to just leave it in the house where it might be confiscated, so he dug a hole in the back yard, wrapped the revolver and ammunition in a oilskin tablecloth, and buried it.

We’d all heard stories about this buried pistol over the years, and finally one of my other relatives decided to dig it up. The revolver turned out to be a double-action Russian Mosin-Nagant. It was quite rusty, but once cleaned up, amazingly it still functioned (it had been in the ground for 30 years). The ammunition, though, was another story. While externally it looked fine, not one single cartridge out of a box of 40 would fire. Chalk that up to poor storage, mostly moisture.

* * * * *

General George S. Patton once opined, “Intelligence is like eggs—the fresher, the better!” One might say the same when it comes to ammunition. Take care of it, and it will work when you need it to. Store it improperly, and when the chips are down, and you hear that loud “click” of the firing pin falling on a dud cartridge, you’ll have only yourself to blame.

I’ll be at the SHOT show in just under a month, and I often have a little chat with Steve Hornady when I’m there. If you have any further questions, I can try to get his take on them too.

Hope that was of some help and interest,


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