#1-Does properly stored gun powder have a shelf life?
#2-Is it true that the longer gun powder sits in its factory containor the more powerfull it will become, or its relative burn rate increases?

I ask because I have alot of Unique HG powder that has been stored in ammo cans for over 15yrs now and I am wondering if it is still safe to reload 45acp and 40s&w rounds with it.

If I did reload with it I would use charges 1.5grns below max and only a few in each caliber till I determined by shooting it was OK and I got no pressure signs.

What do you all think?
Thanks for any help,
Arthur.

Thanks Vaperdog. I once called Winchester and talked to a rep about the same question concerning loaded factory handgun and sabot ammo (theirs) and he essentually told me the same thing. Properly stored it should be fine for at least 25yrs.

Aagin, Thanks.
Arthur.

I bought some IMR4831 in old cans, froma gunshop closeout. The lids were a bit rusty, probably 20yrs old. I loaded my fav. load in my 404jeffery along w/ some current manuf. & shot them over the chrono. The loads were very consistant & within 15fps of the new powder.
I would certainly use your stash of Unique. The formula has changed just a bit over the years, a bit faster than old stuff, so loading down 1gr to start would be prudent. Then work back up.

I am still using Hi-Vel #2, which was discontinued by Hercules in 1964, if that tells you anything. It has "lived" with me in coastal Oregon, northern Alberta, Saskatchewan, southern Alberta , Arizona, and central western Oregon, in that order. I have and use older powders, but have been able to watch the use of this one large batch of Hi-Vel for all those years.

Powder consists mainly of two things: solids and
what laymen might call "vapors" (volatiles). Over time the vapors are given off by evaporation. The result is that the powder becomes slightly weaker with enough age.

Proper storage means under moderate temps, moderate humidity, and in complete darkness (inside the container).

Good powder has a much fresher smell to it than deteriorated powder. I read somewhere, maybe this forum, that you should memorize the smell of fresh gunpowder and you'll then be able to tell if you run across some that's deteriorating. Seem like I also read something about deteriorating powder becoming dusty from some sort of oxidation.

As long as it has remained dry I would use it. It's been my experience that it gets a little weaker as it ages.

Take a teaspoonful and lay it on a stone or other non flamable surface (outside!)and light it. It should start slowly and flare as it hits the densest part of the pile. If it sputters and spits, it probably ahs some moisture in it.

Wear sunglasses! This stuff burns bright.

Handgun powder wil burn faster of course than stick powders designed for rifles.

Amoung other gun things I just inherited a 1/2 full 1# can of HiVel#2.Metal squarish can with a 2 1/2" screw top lid and inside a lift top spout. Now this stuff is not as old as the flake powder I get from pulled German 8mm ,Mil., 1938 manufactured ammo. I load a number of various cartridges with this flake powder and haven't had any problems.

I have powder that is over 30 years old, and it works great.

Keep the lid screwed on tight, and in a cool dry place.

I would have to agree with the others . ( IF ) Powder is properly stored it's useful shelf live can exceed
50 years .

That is not to say it won't lose something in velocity or burn rate over time and storage conditions .

For premium storage conditions a factory type canister in which the Air can be removed , or the volume

in the canister can be replenished IE marbles or some other non reactive materials , to replace the powder as used works best or move to smaller containers . I don't like certain plastic containers so be choosy .

An even storage temp. DRY & cooler the better and it's near factory perfect for as many years as your

likely to use it .

Though it is probably not possible to keep black powder too dry, I think smokeless powder can be stored "too dry". I think the "volatiles" tend to evaporate more rapidly under extremely dry conditions than they do under moderate (say 40% to 50% relative humidity) conditions. Whatever, one does not want it particularly wet either, even though smokeless powder is often kept under water at the manufacturing plants with no particular harm done to it by the water.

AC ; One of the reasons for using an air tight canister is to prevent that vary problem .

5% humidity or 85% in a sealed container will make no difference .

Provided the powder wasn't left open when it was 85% humidity .

Regardless of storage humidity I believe the Key is powder prefers to be Dry and Tight.

When you purchase it remember it had a seal under the lid , I prefer to reuse it myself .

i'm still working over some bonanza 4831 (H4831) that gopher shooters had bought for the govt, pulled out of old WWII 20mm rounds & it works just fine

oh yeah - and i did buy it for $0.45 per pound

#1). I have fired ammo from just after WW I, 1920s. No problem. Clean, Well stored... Friend, gunsmith had a home defense gun, .45 ACP revolver he was showing me once. It was loaded with ammo in moon clips from 1918. He said he wasn't worried. His father was a gun smith and had this lying around... His butt not mine so I didn't argue loudly...
#2). As said, the vapors leave and the exact chemistry changes. Probably weaker.
#3). There is a story, factual, Dupont/IMR made a run of powder toward the end of WW II and left out a "wash" or two. There was "a war on." But the war ended. It got into surplus sale and out to the public. With the acids that did not get "washed out" it deteriorated and had much red dust and changed character. Yes, unsafe. Or so said the NRA in the magazine. 4895? They were not that specific. In brief, not likely you will run into it today.
#4). From people I trust, it is said that IMR powders will pick up moisture from the air and become a trifle slower if exposed to air/humidity. Keith wrote about this for one. At the same time, Col. Nonte, in one of his books, said that ball powders are stored under water for safety reasons. Much harder to catch on fire!

Assuming your powder has been stored in conditions you would live in I would not worry a bit. At the same time, your process seems very wise. Best of luck.

I've been shooting some WWII surplus 4831 since the late sixties and chronographing since the mid-seventies. Its been stored in the original containers in my home. I am unable to detect ANY loss of power or other sign of ageing. Your results may vary, but I beleive the shelf life of properly stored smokeless powder is a lifetime, or more.

Depending on the powder, some of the stuff is already several years old by the time it reaches the shelves.

I bought 6 pounds of Re25. The lot number also had a date of manufacture. I bought it in 2006. It was made in 2000.

quote:

Originally posted by iiranger:
.
#3). There is a story, factual, Dupont/IMR made a run of powder toward the end of WW II and left out a "wash" or two. There was "a war on." But the war ended. It got into surplus sale and out to the public. With the acids that did not get "washed out" it deteriorated and had much red dust and changed character. Yes, unsafe. Or so said the NRA in the magazine. 4895? They were not that specific. In brief, not likely you will run into it today.
.

Nitric acid to be specific. I had to get rid of 8# of it about 6 years ago. A real lawn burner. roger

quote:

Originally posted by iiranger:
#1). .
#3). There is a story, factual, Dupont/IMR made a run of powder toward the end of WW II and left out a "wash" or two. There was "a war on." But the war ended. It got into surplus sale and out to the public. With the acids that did not get "washed out" it deteriorated and had much red dust and changed character. Yes, unsafe. .

May be worth noting the WAY in which it is unsafe. Powder deteriorating due to residual acids is prone to spontaneous combustion as it breaks down. So, it is not stronger, it is more likely to burn your house down while you sleep.

quote:

Originally posted by dawaba:
I've been shooting some WWII surplus 4831 since the late sixties and chronographing since the mid-seventies. Its been stored in the original containers in my home. I am unable to detect ANY loss of power or other sign of ageing. Your results may vary, but I beleive the shelf life of properly stored smokeless powder is a lifetime, or more.

I had some 4831 that had been stored in a Texas garage before I got it. After I had it about 7 or 8 years i started smelling the acid. When you opened the container it had a brownish purple haze float out. Some round that I loaded cracked around the neck. The powder finally started looking wet. I poured 8 lbs into a string and burned it.

On the other hand Hercules (now Alliant) has some original Unique mfg in 1898 (yeah 0ne eight nine eight) that has been stored in a large jar of water. The story I ready in Handloader magazine showed that they occasionally remove and dry small amounts for testing. the ancient powder still works as it originally was designed to.

Thanks to all who took the time out to educate me about long term powdwer storrage. I am sure quite few other reloaders besides myself benafited from all the great info posted here.

Again, thanks to all.
Arthur.

I have access to a gentleman who is an energetics expert. I asked him about smokeless powder lifetime.

He told me that powder starts deteriorating the day it leaves the powder mill. The rate of deterioration of double based powders is governed by the Arrhenius equation. http://en.wikipedia.org/wiki/Arrhenius_equation. Single based powders apparently deteriorate in a linear fashion.

What the expert told me was that double base powders are made of nitroglycerine (NG) and nitrocellulose (NC). The NG wants to wick its way, through capillary action, into the NC. Forming a lower energy state compound. In the process of combination nitric acid gas is released. As nature wants to go to a lower energy state, this reaction is inevitable. There are preventive stabilizers in the powder which either slow the reaction down, or eat up the nitric acid. I forget the exact function. The stabilizers get consumed over time.

Heat accelerates the combination process. Exposing powder to high temperatures for extended periods of time is bad. The expert said, if you could freeze the powder without introducing water, you could slow the process down.

Cool dry storage conditions, he actually said “articâ€, are about the best for long term storage of powder.

The expert said that powders are initially tested 10 years. (I think, could have been 20 years). They put a paper in contact with the powder. If the paper changes color, nitric gas is present.

If the paper shows a problem, they then chemically test the powder for the amount of stabilizer in the powder. If that drops below 20% original, than the powder is scrapped. You have to have the original powder records to know how much stabilizer was in the powder.

If the powder changes color, it is bad. It is grossly bad. It was bad a long time before the color changed. And it is time to pour it out. That is when you typically see red in the powder can (acid gas eating the can up) and red powder.

I was told that when enough nitric acid is released, the powder will spontaneously combust. As the Military is extremely scandal sensitive, they won’t tell anyone that big bunkers have blown up. And that fires in storage depots happen quite often.

The Navy used to store cannon powder in pools. This powder was to be recycled. I guess the water absorbed the nitric acid, or kept everything cool preventing heat build up.

I have had half of my surplus 4895 powders go bad. About 8 pounds turned red and was poured out. About 8 pounds did not turn red, but went bad in the case. First indications that I had a problem were that loaded cartridges started having a lot of split case necks on firing. Then case necks started to crack on the loaded ammunition. When I pulled bullets, I smelt nothing, in the case or in the bottle, but I found green corrosion on the bottom of bullets. I believe that nitric acid was weakening the work hardened areas of the case, and causing corrosion on the bottom of the bullets.

Incidentally, the powder shot exceptionally well, that is for cases that did not have case neck cracks. I shot some exceptional scores with the stuff at 600 yards with 168 Match bullets, just after loading.

it is what goes on INSIDE the can that ruins powder. if there is a very small air leak in the can the powder will go bad. pour it into your hopper and a cloud (red w/ IMR) will float out of the hopper. pour it out. i loaded 3 lbs. of red dot that was 50 years old. i assumed the tin can would ruin the powder on the bottom. it did. extremely weak, as i loaded some to see, but 95% was good. flake powder will curl up and change color going lighter in color. i sold the red red-dot can, empty, to a collector for $30.this was red-dot w/ a hole in the center of the flake.