Powder & Loaded Ammo Shelf Life


September 7, 2008, 04:39 PM
If I stuff freshly minted reloads into ammo cans with a dessicant how long could I expect the powder in them to last under environmental temperature swings (outdoor storage in Kansas, think 10-130 deg F). I'm debating storing my powder/ammo/primers in my basement vs. my outdoor shop.

On a side note, does anybody have direct experience with burying and later recovering ammunition and/or reloading components in a non-arid environment (AKA "caching")?

Seems to me that if the main cause of powder degredation is high temperatures, then geologic storage would be best if one wanted to store a largish (50-100 lbs) amount of powder in the event of future shortages or outright bans (or "discontinuations" ;)).

How about for primers?

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September 7, 2008, 05:04 PM
Stored in the basement, the shelf life would be indefinite.
Perhaps forever, or at least a lifetime.

Outside in a Kansas shed, not so long.

It is the high summer temperature, and daytime/nighttime temperature swings that do in the powder.

I have ammo in GI cans from the 60's stored in the basement that is as good as the day it was made.

If I was to store ammo or powder buried, it would be in waterproof GI cans, or Tupperware containers, in a 55 gal plastic drum with a screw-on lid. (old Pickle barrel). Then there would be plenty of drainage under & around it, and an insulating lid over it, below ground level.

And maybe even a sump-pump! :D


Eric F
September 7, 2008, 06:05 PM
if one wanted to store a largish (50-100 lbs) amount of powder check local laws some places require notification of an amoutn over X pounds some places have a limit. Where I live the city has a cap on black powder but smokeless is unlimited.

September 7, 2008, 06:30 PM
Root cellar or storm cellar.

It's been demonstrated from time to time that smokeless ammunition hasn't been around long enough to establish an outside limit. In the past I've made no effort towards extended storage but it happens and as I get older myself it gets into 40 years old or more. There are folks with some Ball C (1) still floating around and such. Rumor says primers get to be more erratic in bench rest terms as they age but plenty of them still go bang.

September 7, 2008, 06:52 PM
I've shot some of my dad's ammo that I loaded 49 years ago,stored in a non-cooled non-heated room,just dry. it still goes bang.I've also got some 1926 dated 303 Brit stuff,stored under less than good conditions,still goes bang.if it's kept dry,it should last till Al Gore's global warming floods us all out. jwr

September 7, 2008, 08:05 PM
I had a talk with a guy who is a energics specialist.

He said double base powders are a mixture of nitrocellulose and nitroglycerine and stabilizers.

The nitroglycerine wants to wick itself through the mixture into the nitrocellulose, to form a lower energy compound. When it does, a nitric gas and heat is released as part of the reaction.

The stabilizers form a temporary barrier. I assume they are consumed over time.

When powder is seriously old, this nitric gas and heat will start a self combustion. This has blown ammunition bunkers. The military does not like to talk about it, but it has happened.

The military tests smokeless propellants around the 20 year mark. The first test is simple, powder in a test tube with a special paper. The paper changes color when nitric gas is present. Then they test the propellant for composition. The military has data sheets which indicate the % of stabilizers in the original mix. When the stabilizers get below a certain percentage (I don’t remember), the lot is scrapped.

I don't have a chemical analysis lab, so I have to look for gross conditions.

Gross evidences of corrosion in the powder: the powder turns red and corrodes brass, copper, removes the tin from inside a can.

Heat is very bad for powder. The Energics guy said the reaction follows the Arrhenius curve with respect to heat http://en.wikipedia.org/wiki/Arrhenius_equation. Cold, dry cold without water, is good. I understood water crystals in the powder are bad. If you could store your powder in an unchanging artic environment, the chemical reaction would be very slow.

So how long can powder last, if it was stored in cool conditions, a very long time. Well over twenty years. Assuming it was well made. There was something about improper acid wash at the factory limiting the lifetime of powder.

I think there is a post here about a guy who tested gunpowder devices stored in the artic. I think the conclusion was that nothing changed over the lifetime of testing he performed.

September 7, 2008, 08:23 PM
Just from my personal experience . . .

When I quit reloading after my first go-round I stored all my ammo and it sat in the attic of various midwest garages for 20+ years. Temperature swings in this area (in a garage attic) will vary from I'd guess -20 degree's in the winter to +120f in the summertime.

Fast forward 20+ years and to the purchase of a new Kimber 1911 . . ..every single round went bang and some of them made some mighty fine groups. In looking at my notes on the reloads I was using Mil surp powder when I loaded them so who knows how old it was when I started using it.

Just my .02


September 7, 2008, 09:12 PM
Very VERY good responses people.

I'm considering purchasing a large order of milsurp powder (pulldown AA#7, WC846 & WC860) most of which is supposedly already 8 years old. I've also been looking at just buying new power pistol (or longshot), varget and maybe something heavier for magnums and squirreling mosy of it away.

Slamfire1, Thanks for the info, I might just call Hogdon and see if the can release rate information for the stabilizers to the public. If it's a simple decomposition reaction modeling it should be straightforward. PS: If nitric acid is an indicator, you can also look at your hands after handling the powder. If you see yellowish stains your powder is acidic. Where did you meet a combustion specialist? I'd love to knock back a beer with one of those guys!

dmftoy1, do you know the designation of the milsurp you used? Might be interesting to look up the type and year of manufacture.

Eric F, good idea, I'll look up my state's fire code.

September 8, 2008, 12:47 AM
For me, all propellant powders are like women.....they are all good, some are just better than others. I've had IMR powders deteriorate, rust the can, and fill up with red dust. Still, some of the calibers I shoot do their best with IMR powder. So, I buy it as needed. For "caching" I buy single based and ball powders. I've yet to see deteriorated Hercules (now Alliant) or ball powder. I once used up a can of Unique that my grandfather gave me that I know was over 50 years old, and it performed just fine.

I'm also working on a large batch of assorted primers bought at a garage sale that were originally (the dates were hand written on the cartons) purchased starting in 1977. Out of over 15K primers, I've not had a misfire yet.

Keep loaded ammo, powder, and primers cool and dry, and they will last a long, long time.

September 8, 2008, 07:21 AM
My notes from my younger years are nowhere near as detailed as they are now. :)

It was HP38/W231. At the time the guy I was buying it from was buying brass and powder from some sort of government auctions and he used to have incredible deals on TZZ .45 ACP bras and these massive kegs of W231. I was just looking through my notes and I was paying $2.45 for a pound of it. (aaah, the good old days)

FWIW - some of that TZZ brass is still in rotation. :)

September 9, 2008, 12:30 PM
I just got some in a trade!

September 9, 2008, 01:51 PM
I've been reloading using powder and primers that my dad had used. These powders, including most of a pound of Unique, have been sitting in a covered barn for 18 years and had been used for some time before that. The temp. swings would go from 110 down to 28 to 30 degrees in winter, although with very low humidity. All of the primers have worked, and the Unique powder has fired every time. I'm getting ready to try some of the IMR powder (4064) and I would expect it to work just fine.

I have also fired WW2 military rounds out of my 03-A3 Springfield that were around 60 years old. All of the rounds fired with no squibs.

September 10, 2008, 06:28 PM
I routinely shoot .38spl wadcutters I loaded in the early 70's with Bullseye and have never had a problem. I don't remember what primers were used. This ammo has been stored inside the house so no extreme temperature spreads.

I have a supply of US .45acp dated 1918. I recently fired some from my 1918 manufacture US property marked Colt 1911. I've had this gun and ammo for about 35 years and occasionally shoot it just for fun. I've never had a misfire from the 90 year old ammunition.

I hope I'm around to shoot some when it's 100 years old!

dan :)

September 11, 2008, 11:46 AM
Geo storage sounds good, and local codes are less relevant when no one knows it exists... :neener:

If that is the direction, plastic drum would be best, can't rust and groundwater is non-factor if lid is watertight. Ground temp doesn't even come CLOSE to air temp swings, maybe we have a geologist here on staff who could tell correlation between depth and average temp for a given latitude? :scrutiny:

My woodworking catalogs sell a product called Bloxygen, inert heavier-than-air gases used to squirt into a can of finish before sealing to prevent oxidation. Just for an extra insurance for this project buy a can or two and empty them into the drum before putting the lid on...

September 11, 2008, 12:34 PM
Once you get past the immediate surface down to circa 200 feet down, temperature remains a pretty constant 55 degrees F.

After that, on average it rises about 1 degree F per hundred feet.

This is a practical rule of thumb but will vary dependent upon circulating ground water, rock structure, local volcanoes etc

Image below is an observed temperature measurement over several years from immediate surface down to approx 5 feet. You see that the temp variation quickly drops as you get past the immediate surface.

Measurements were from a study in Hebei Province, China.


September 12, 2008, 12:42 AM
Plinker - Have you considered heat and A/C for your outdoor shop? I'm in Kansas as well and can highly recommend a heated and cooled shop for reloading and storage. My reloading stash isn't as large as what you have noted for contingencies, (only about 30 pounds of powder and 12K primers) but is still too large for peace-of-mind basement storage.

My shop is in a corner of a large outbuilding, well away from the house, and includes toilet facilities, hot water heater, washer/dryer and a utility sink. Through-the-wall A/C unit and gas heater keep the wide Kansas temperature swings tamed. In addition to reloading supplies, I also store several thousand rounds of ammunition there.

Unless I'm actually working in the shop, I merely keep the winter temperature a few degrees above freezing and the summer temperature under 80. I can tell you, reloading in a heated shop is a great way to pass the cold Kansas winters........ (The only downer is mushing through the ice and snow from the house to the shop.)

September 12, 2008, 02:27 AM
If stored properly even in temp changes shouldnt be much of a problem. I can tell you from personal experience though, that ammo stored in Illinois weather in a cheap storage unit will go bad after about 3 years. Only about 1/2 of it went bang. Lots of humidity, no dessicant.

September 12, 2008, 07:30 AM
I'm too cheap to hvac my shed and its possible that if I do that my wife will push to refinish it and turn it into a guest room for my brother inlaw :scrutiny:. (its very well constructed) My basement is also a garage/shop. (one can never have too many eh?)

Interesting to hear about self storage ammo failure. I had to put my guns in one for a year but my ammo still all shoots. I was careful to keep everything elevated and in ammo cans though.

September 12, 2008, 09:12 PM
I guess we knew that.

Most of the US milsurp stuff is stored under really good conditions and will be nearly as good as it was when it was manufactured. By that, I mean components in particular, the huge lots of surplus powders you see sometimes. The more it's exposed, the more it degrades, so the ammo isn't quite as pristine as cannister powders that have been in their sealed cannisters since the Korean war.

I'm still shooting WWII surplus ammo and it still goes bang NEARLY every time. The 22 ammo I bought over 30 years ago - well, once in awhile, a couple dozen duds out of a 500 round carton. That stuff hasn't always been stored properly. If you pay attention to tightly sealing things, the stuff will very likely outlast you and STILL be very close to spec as manufactured. I have powders that were bought in the 60s that most certainly were surplus - like IMR 4064 that was probably left over from WWII, and it's good as new. Same goes for primers - I recently used a few cartons of circa 1972 rifle primers. No failures from a couple thousand rounds. They didn't spend the last 35 years outdoors in the toolshed.

I keep my components and 'cached' ammo in my basement. I'm pretty sure ammo, like anything else, does better in stable, fairly dry conditions.

September 13, 2008, 01:27 AM
Interesting to hear about self storage ammo failure. I had to put my guns in one for a year but my ammo still all shoots. I was careful to keep everything elevated and in ammo cans though.

Yeah, that happened to me. A lot of ammo that me and my uncle had reloaded actually. He seems to think some of it may have been because the crimp just wasnt tight enough on some of the rounds and moisture got in. Ithink it was just too humid around here. There was some factory .38spl wadcutters and some factory .45acp jhp in there that went bad too. I talked to him about it just yesterday when we were loading and we figured out they had actually sat in storage for 4.5 years.

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