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Old 03-03-2015, 08:03 PM
Slamfire Slamfire is offline
Join Date: Feb 2010
Posts: 110

The life time for gunpowder has been called "interminable", which is another way of saying, unpredictable. Gunpowder has a life time, if you ever took thermodynamics you will understand it when I say gunpowder is a high energy compound that is breaking down to a low energy compound, and you will understand why, and why this is perfectly natural. Just exactly when it deteriorates to a useless state is impossible to predict with any certainty, from the outset, but the lifetime of gunpowder is in terms of decades, not centuries. Something else to remember about this, it gets worse and more dangerous with age.

Whether powder is good is not easily answered unless the powder has gross indications of going bad.

The gross indications are the bitter smell due to NOx, red powder granules, fuming gas emissions, others have said “red gas”. By the time you see this the powder went bad a long time before.

Half of all the surplus IMR 4895 I purchased went bad. The first 16 lbs, I used up eight pounds quickly. For whatever reason, I pulled the bullets on some of that stuff and found green corrosion on the bases of the bullets. Similar to these pull down bullets from old US ammunition. Not the horrible one, but the small green spots.

I don't remember what US ammunition these came from I pulled them decades ago.

It took a while till I found reason to use the rest of that surplus IMR 4895. When I opened the bottle top, it smelled bitter, red dust flew above the opening. I decided to get rid of it, but not have it wasted. I gave the jug to a machine gunner guy and he put it in his laundry room. Passing by the laundry room he tossed soiled shorts at the hamper, but missed. The shorts ended up on top of the powder bottle and stayed there overnight. Next day my friend found that escaping acid gas from the bottle had eaten holes in his shorts!! :what: This so unnerved my friend, he poured the powder out over his lawn.

Actually this was the best thing to do, and had I know of the hazards of old deteriorated gunpowder, I would have poured it out on the lawn and not given to him to shoot.

Since then I have had more surplus 4895 powder from a different vendor go bad in the case. Visual inspection of the ammunition revealed green corrosion on the bottom of the bullets and cracked case necks.

This powder never smelt bitter at all. I shot this powder in highpower matches and it shot exceptionally well, but case necks cracked after firing. I also received “funny” retorts and the occasional sticky extraction. The longer the ammunition was unused the more cases necks would split when fired. In time virtually all of the remaining 700 loaded cases experienced cracked case necks without being fired.

This powder is from a FA 11-1898 30-40 Krag cartridge. Obviously it is bad.

I sent an IM expert the pictures of my corroded bullets and pulled Krag red powder, and this is what he wrote back:


The red color indicates that the stabilizer is depleted and the redox reaction is degrading the nitrate ester. (I assume this is a single base gun propellant, and the nitrate ester is NC.) Please dispose of this powder and ammo supply before it starts to get warm or self-heat (via autocatalytic exothermic reaction). This stuff can be a runaway reaction and spotaneously explode in storage.

The cracked case necks are proof that the outgassing of NOx is occurring. The pressure build-up is evidently enough to fatigue the metal at a high stress location in the cartridge case (@ the neck bend). You should also see a bulge in the cartridge base (where the firing pin would strike b/c there is a circular joint crimp there between the two metals). This ammo would explosively vent at the crack if you tried to fire it in a gun. Just like the Garand example you sent. Please discard this ammo.

The corroded ammo is the same as above (redox reaction gassing NOx) except this stuff actually got wet too. Water provides a medium for corrosive acid reactions to result. Please discard this ammo.

Lessons learned -
(1) Ammo has a finite shelf life
(2) Ammo can be dangerous

From what I had read on the internet, which is a repeat of what is said in gun magazines, powder has an “indefinite” shelf life. I think we all remember reading statements to the effect that powder lost energy as it got old, making it essentially benign. This information is not only wrong, it will get people hurt.

Years later I ran into a Naval Insensitive Munitions expert. This IM expert explained that powder is deteriorating the day it leaves the factory. Nitrocellulose decomposes through the reduction-oxidation process, he called it Redox. The expert said “The molecular stability of the functional groups on the organic chain determine the life time of the nitrocellulose molecule.” This guy actually writes and talks like this, he is extremely bright with a PhD in Chemical Engineering.

The bottom line is that nitrocellulose is a high energy molecule that is breaking down to become a low energy molecule. Anyone who has taken thermodynamics will realize that this is obvious, everything is breaking down to a lower energy state, but somehow, shooters have been lulled into thinking that the second law of thermodynamics does not apply to our sport.

Heat accelerates the deterioration/decomposition of powder and the rate is directly proportional to the Arrhenius equation, which is an exponential function. Maybe this is a simpler way to say it: the lifetime of ammunition decreases exponentially as temperature rises. This table is instructive on how quickly heat deteriorates smokeless propellants:

UN manual on ammunition inspection. See section 7.3.

Surveillance and in-service proof - the United Nations[/B

If you read Insensitive munitions literature, you will see that they use high temperature to accelerate aging of smokeless propellants. Keep this in mind as some of the data I am going to show is from accelerated aging tests.

As gunpowder gets older it does not get safer to shoot. Old gunpowder will, and has, blown up firearms. The basic reason is something called “burn rate instability”. For all your cartridges you want a nice and smooth pressure curve. If the burn rate is irregular, because the nitrocellulose powder grain breaks down irregularly, there will be peaks and valleys instead of a smooth pressure curve. These irregularities can interact in such a way that pressures spike. Double based powders are a combination of nitroglycerine (NG) and nitrocellulose, the NG is there for an energy boost, but unfortunately NG causes a new set of problems. NG is apparently not bound to the powder grain but is a liquid and it migrates. NG is wicked to the surface of the powder grain over time, one causal reason, water condensing and evaporating on the powder grain surface. Apparently the evaporating water molecules pull on the NG. I was told that created a NG rich surface. So, even though the total energy of the grain has decreased due to breakdown, the surface is NG rich and that will spike the initial burn rate. Another thing NG does is accelerate the breakdown of the base nitrocellulose molecule by attacking the double bonds holding the NO molecules. Unfortunately all ionic compounds attack those double bonds, water is a main offender because it is always in air, is a polar covalent ion (acts like an ionic compound) and thus you know the reason you were told to store gunpowder in a cold and dry environment. Quality ammunition is manufactured in humidity controlled environments, between 40% and 20% humidity, but they don't go lower due to electro static discharge concerns. Incidentally rust is bad and that rust that came out of those old tin cans accelerated the aging of gunpowder, and I think, is why they went to plastic containers.

There is almost no data on the internet because all that was ever needed to be known about gunpowder aging was determined well before WW2. However ball powders did come out at the end of WW2 and I was able to find this data showing that gunpowder at the end of its lifetime will pressure spike. I asked you remember that heat is used to accelerate the age of gunpowder, so what you are seeing is in fact because of “age”, not heat, but it took heat to age the powder quickly. The IMR is a single based and the WC is a double based ball powder.


Frankfort Arsenal 1962

3. Effects of Accelerated Storage Propellant and Primer Performance

To determine the effect of accelerated isothermal storage upon propellant and primer performance, sixty cartridges from each of lots E (WC 846) and G (R 1475) were removed from 150F storage after 26 and 42 weeks, respectively. The bullets were then removed from half the cartridges of each lot and from an equal number of each lot previously stored at 70F. The propellants were then interchanged, the bullets re-inserted, and the cases recrimped. Thus, four variations of stored components were obtained with each lot.

Chamber pressures yielded by ammunition incorporating these four variations were as follows. These values represent averages of 20 firings.

When I discussed pressure problems and old ammunition with a machine gunner buddy, he said that explained the two top cover explosions he had with old Yugoslavian 8 MM ammo. Machine gunners shoot pallets of ammunition and so they are more likely to encounter the occasional overpressure round. The pictures of this Garand blowup with WW2 ammunition has created posts of angry denial from hoaders. I collected a number of threads with blowups with old surplus ammunition, and it is surprising just how many firearms have blown up with old ammunition, and yet, the shooting community has not figured out the cause. There are a number of posts of pressure problems with the old Greek ammunition on this forum, yet the posters just assume the ammunition was overpressure when it was issued. Something I highly doubt, but what has happened is that as the powder grain has deteriorated, combustion pressures climb. The phenomena is burn rate" instability. A gunpowder grain is assumed to burn evenly, but if the grain has deteriorated unevenly, when it burns you get interacting and conflicting pressure waves. Uneven burn rate is bad, moves the pressure curve slope, and the end result is high pressures. If the powder grain physically breaks down, there will be powder dust in the case and the surface area of that dust is huge compared to the original grain, and that will spike the pressure. Google coal dust explosions and find out the explosive problems that occur with coal dust, or cotton dust as another example. Burn rate instability is a problem for all devices loaded with smokeless propellants, big and small, and a primary reason old solid propellant rockets are taken out of inventory, because too many of them blow up if fired.

So to summarize, powder does not get better with age, heat ages powder fast, old gunpowder will blow up your firearm. Anyone with a $100,000 dollar irreplaceable machine gun should seriously consider the practice of shooting cheap surplus military ammunition. Machine gunners shoot orders of magnitude more ammunition than most people, so as they are burning through a pallet of surplus ammunition, they are more likely to find that statistically improbable bad round. If that cheap surplus ammunition wrecks the registered part of the machine gun, the machine gun is a total loss. The BATF is not your friend in this matter as the policy of the Federal Government is to reduce the number of machine guns in the hands of the public. You blow yours up, guess what, that is considered a good thing, and you have to find another to replace the one you destroyed. Since the total number will always go down, the next one will cost more.

There are more nasty things that happen with gunpowder and I am going to try to approach this section so you understand observed phenomena:

I can’t say it any better than the Dec 2003 Propellant Management Guide:

Stabilizers are chemical ingredients added to propellant at time of manufacture to
decrease the rate of propellant degradation and reduce the probability of auto ignition during its expected useful life.

As nitrocellulose-based propellants decompose, they release nitrogen oxides. If the nitrogen oxides are left free to react in the propellant, they can react with the nitrate ester, causing further decomposition and additional release of nitrogen oxides. The reaction between the nitrate ester and the nitrogen oxides is exothermic (i.e., the reaction produces heat). Heat increases the rate of propellant decomposition. More importantly, the exothermic nature of the reaction creates a problem if sufficient heat is generated to initiate combustion. Chemical additives, referred to as stabilizers, are added to propellant formulations to react with free nitrogen oxides to prevent their attack on the nitrate esters in the propellant. The stabilizers are scavengers that act rather like sponges, and once they become “saturated” they are no longer able to remove nitrogen oxides from the propellant. Self-heating of the propellant can occur unabated at the “saturation” point without the ameliorating effect of the stabilizer. Once begun, the self-heating may become sufficient to cause auto ignition.

Actually there are only a few compounds used as stabilizers, and as the Propellant Management Guide tells us, stabilizers are consumed with age.

This is a good reference on stabilizers,


Nitrocellulose-base propellants are essentially unstable materials that decompose on aging with the evolution of oxides of nitrogen. The decomposition is autocatalytic and can lead to failure ofthe ammunition or disastrous explosions.

They are using heat to age the powder and as the powder ages, the stabilizer content decreases.

The bitter smell and red color (probably nitric acid gas) we see and smell in very old gunpowder is a consequence of not enough stabilizer left to sop up all of the NOx. As NOx escapes it reacts with water to produce nitric acid gas. That nitric acid gas corrodes brass, bullets, weakens brass, is evidenced by cracked case necks, eats up the ammunition containers; nitric acid gas is nasty stuff. I am certain that a cloud of red fuming nitric acid gas is as toxic as any of the chemicals used in WW1 for chemical warfare.

Our Armed Services have stockpile surveillance programs (but each Service does theirs a little differently) and one of the easiest things to show that gunpowder is at the end of its service life is that red fuming nitric acid gas. Of course there are a lot of tests, if you want to see all the different tests the military uses look at Mils Std 286 Propellants, Solid: Sampling, Examination and Testing to be found at

One common test for gunpowder age is placing the suspect powder in an oven at 65 C (150 F) until it fumes. If the sample fumes within 30 days the lot in the field is either chemically tested for the percentage of stabilizer or it is simply scrapped.

This is from a 1969 Symposium:

This is from a 1970 Symposium:

Each service has its own peculiarities, the Navy expert told me they keep master samples in test tubes. In the test tube is a methyl violet paper, if the paper changes color, they track down the powder lot and test to see how much stabilizer is left. If the amount is less than or equal to 20%, the lot is scrapped. I think this is called the Methly Violet test, or Talliani test in Mil Std 286. Page 5-11 of the 2003 Army Logistics Propellant Management Guide provides the protocols for their Stockpile Propellant Program. The trigger for investigation is: "When Master Sample Stability Failure Occurs". The Navy and Army are consistent in that they scrap powders and propellants when the stabilizer decreases from 100% to 20%.

So, what do you do if you don’t have a chemistry lab to check the percent of stabilizer? Well all you have left is the gross indications of seeing fuming nitric acid and smelling a horrible bitter smell. The smell will knock your socks off. If you see or smell fuming nitric acid the powder went bad long ago. The stuff is absolutely unsafe to shoot and unsafe to store. More on the second point later.

This bottle of Vihtavouri N150 is outgassing nitric acid gas and should be poured out at once before it autocombusts!

My Navy expert provided 'rules of thumb' concerning the safe lifetime of double based and single based propellants. The rules of thumb are: Double based powders and ammunition are scrapped at 20 years, single based 45 years. In his words These 'rules of thumb' are particularly useful when the protocol fails. The protocol can easily fail when workmanship or good housekeeping measures are not followed during manufacture of propellant and/or rocket motor or during storage of the weapon system components, respectively.”

I want to say, given hot storage conditions, sloppy manufacture, the lifetime of your gunpowder can vary considerably. Rules of thumb are best guesses and best guesses are guesses. Sometimes best guesses work out the way you predicted, when they do people will call you a prophet and you will pat yourself on the back for being a genius. When best guesses go wrong, you will wear the dunce cap and wonder what that word “hubris” means.

Take these numbers with a grain of salt, early in the last century the storage lifetime of smokeless powders was considered to be 20 years or less:

Here, Hercules is bragging about Bullseye powder still being good at 25 years.

Army Ordnance Magazine, June 1931, page 445 says:

Smokeless powder constitutes one of the greatest hazards from a storage standpoint, due to the fact that it is subject to deterioration and at the best cannot be expected to have a life greater than about twenty years…….Master samples of all lots of smokeless powder are under constant observation in the laboratories at Picatinny Arsenal. Should any of these samples indicate rapid deterioration, notification is given at once, and steps are taken to use this deteriorating material within a very short period, if possible, or else withdraw it from service.”

Federal says their ammunition has a ten year shelf life:
Federal Ammunition :

What is the shelf life of ammo and storage?

Store reloading components and ammunition in a cool, dry place, protected from direct exposure to sunlight. If stored properly there is a 10-year shelf life on loaded ammunition.
So of the nasties involved with old gunpowder, this is the final one that I can think of: auto combustion. You probably noticed in the previous references statements that old gunpowder will auto combust. Well it can and it will. Fire is the path to the state of lowest energy. You can do it with a primer, or gunpowder will self murder itself without your help. There is a debate within the Insensitive Munitions community about the “five inch rule” Some advocate the theory that ammunition smaller than a five inch shell the metal casing will conduct heat away from the propellant fast enough that the propellant won’t auto combust in the case. My Naval Expert says this is bogus, but anyway, loaded small arms ammunition is less of an auto combustion risk than large artillery shells. However, gunpowder in bulk is a known risk.

The military does not talk about this, but bunkers and ammunition storage areas have gone Kaboom due to old powder. That nitric acid builds up, creates heat, and the stuff blows up. It blows up inside the case or the shell. All you have to do is Google "Ammunition Depot Explosions" and you will find that, on average, one ammunition dump explodes per month somewhere in the world. This video of one blowing up is quite impressive:

This section is from the Dec 2003 Propellant Management Guide:

c. During the period 1984 through 1997, seven propellant auto ignition events occurred at U. S. Army Material Command (AMC) Installations.

1984: Lake City AAP

IMR powder that was only 5 years old auto ignited and the above round magazine and its contents were destroyed. More than 100,000 lbs of powder deflagrated.

1984: Lake City AAP

The same lot of IMR powder, a fragment quantity isolated and saved for critical production testing, auto ignited two months after the previous fire. Only a small quantity of powder was lost, but another magazine was destroyed.

1985: Blue Grass Army Depot

The local-stocks storage magazine use for demilitarization activities contained high explosives material as well as unmonitored M10 propellant powder. Auto ignition of the powder and its resulting deflagration gradually ignited the other energetic materials present. The earth covered magazine and its contents were destroyed.

1987: Lone Star AAP

Benite was stored in a heated magazine so that it could be temperature conditioned prior to loading into production items. The building became overheated which accelerated the rate of decomposition of the benite to a point that auto ignition occurred. The structure and contents were lost.

1989: Hawthorne Army Depot

8-inch, 55-caliber propelling charges loaded with single-base propellant auto ignited in an earth-covered magazine more than one year after the Navy ordered the lot destroyed due to low stability. The magazine contents of 30,715 lbs of various propellant were destroyed and the magazine was heavily damaged.

1996: Red River Army Depot

Explusion charge assemblies for large caliber artillery rounds, each charge filled with only one ounce of M10 propellant and stored 250 to a box, auto ignited. The earth covered magazine and its contents were totally destroyed.

1997: Hawthorne Army Depot

M9 flake propellant bags that had been removed from 81 mm mortar round were bulk-packed and placed into long-term storage. A container of unstable propellant auto ignited, and all 20,000 lbs of propellant inside the earth covered magazine were destroyed. The magazine was severely damaged. Value of content lost was more than $3,000,000, which the cost to repair the magazine was $164,000.

Military Surplus Powder autocombusting

I run a long range shooting club here in NM. Yesterday a member approached me with a question about a powder he is using. He said " it's fuming" ........What?

I walked down and sure enough the powder was outgassing a very heavy oder of ammonia and Nitric Acid fumes. The powder was slowly turning sticky and had,from over night, corroded the brass cases and the projectiles.

This powder is milsurp pull down IMR-5010 powder that was sold in bulk from the long gone Talon company. Weidners and Pats reloading sells this powder in black plastic 8 pound jugs. There are no lot numbers or dates on the label.

I have been reloading since 1964 and have never seen this happen before. As you know nitro-cellulose uses Nitric Acid to make the propellant. Some how the acid was not neutralized correctly. When the acid is not removed from the powder grains, the deterent coating will break down and uncontrolled burning will happen. The powder may detonate rather than burn

If any of you have any powder that was OK a few months ago you may want to check it again. This powder was normal just last winter. Now it is breaking down. It was stored in a cool room. It was not left in the sunlight.

Chris at Weiders has been notified.

This was purely a PULLDOWN powder issue. NOT a Virgin IMR-5010 issue. I know the guy this allegedly happened to (Paul A. of Albuquerque). I suggested he post the source, acquisition date, etc but to date he has not. He told me the powder was PULLDOWN IMR-5010 from Wideners allegedly told him they would not replace the powder as his storage of it was beyond their control. Also, he had no direct status with them as he obtained this particular jug from another guy that had bought it from wideners.

I personally know the guy this happened to and unless you see some sort of acrid fumes coming off your powder, I wouldn't worry about it. Paul is a real cheap skate. He was loading $2.00 Lehigh 800 grainers with surplus powder. Silly way to save $0.25.
1. 10-02-2009, 11:02 AM#6

[b]Cincinnati Kid

That IMR 5010 powder that came from Talon has caused several large fires here in Ohio, two of them locally to a friend of mine, and one large fire in Northern Ohio that I know of. Anyone who has any of that 5010 powder that came from Talon needs to dispose of it if it shows any signs of breaking down. I wouldn't trust any of it.

Last edited by Slamfire; 03-04-2015 at 02:25 PM. Reason: Added, deleted, moved material around, and probably made it more confusing.
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