I am so proud of this forum. Years ago, any suggestion that gunpowders deteriorated with age would be met with hissing, spitting, insults, and name calling. The denial was strong and vehement. Now posters understand it better and accept it happens.
The basics are, gunpowder is breaking down from the day it leaves the factory. It also breaks down unpredictably, so an exact shelf life is impossible to predict. The basics of breakdown are easy to find in military literature.
Ammunition Surveillance Procedures SB 742-1
https://armypubs.army.mil/ProductMaps/PubForm/Details.aspx?PUB_ID=1001119
Chapter 13 Propellant and Propelling Charges
page 13-1
WARNING
Nitrocellulose-based propellant can become thermally unstable as the age. The normal aging process of the propellants involves deterioration of the nitrocellulose with an accompanying generation of heat. At some point, the propellant may reach a state where heat is generated faster than it can be dissipated. The accumulation of heat can lead to combustion (auto ignition). Chemical stabilizers are added to propellants to slow the aging process. In time, the stabilizer levels will drop to a point where the remaining effective stabilizer (RES) is not sufficient to prevent an accelerating rate of decomposition. When this point is reached, the propellant may auto ignite, with possible catastrophic results to property and life. Monitoring the stability level of each propellant lot is essential for continued safe storage.
Page 13-5 , Table 13.2 Propellant Stability Codes.
Stability Category A 0.30 or more Percent Effective Stabilizer
Acceptable stabilizer loss: safe for continued storage
C 0.29-0.20 Percent Effective Stabilizer
Significant stabilizer loss. Lot does not represent an immediate hazard, but is approaching a potentially hazardous stability condition. Loss of stabilizer does adversely affect function in an uploaded configuration. Disposition instructions will be furnished by NAR. All stability category “C” assests on the installation must be reported in writing…
One year after becoming stability category “C” a sample of the bulk propellant lot or the bulk-packed component lot will be retested. If the lot has not deteriorated to category “D”, it will be retested each year until it has been expended, or it has deteriorated to category “D”, at which point it will be demilitarized within 60 days.
D Less than 0.20 Percent Effective Stabilizer
Unacceptable stabilizer loss. Lots identified as stability category “D” present a potential safety hazard and are unsafe for continued storage as bulk, bulk-packed components , or as separate loading propellant chargers. Bulk propellant, bulk –packed components and separate loading propelling charges will be demilitarized within 60 days after notification of category “D” status.
I found in another document that the 20% or less stabilizer content rule is based on the assumption that the gunpowder will not ignite in five years. This gives the military time to identify, remove, and demill the stuff. If you live near Camp Minden Louisiana, and heard all the kabooms, that is old munitions exploding before, or during, demilling. There was a big one that made the newspapers and a shooter I met, heard from 90 miles away!
New Information: Bunker blast at Camp Minden
By USAHM-News on October 19, 2012
6 arrested in Camp Minden explosives investigation
http://www.fox8live.com/story/22637088/la-company-managers-indicted-in-explosives-case
look at the picture!
Camp Minden: From blast to possible burn
http://www.ktbs.com/story/28065933/camp-minden-from-blast-to-possible-burn
Propellant Management Guide
http://www.fas.org/man/dod-101/sys/land/docs/prop_guide.pdf
DEFINITION:STABILIZERS
Stabilizers are chemical ingredients added to propellant to prevent auto ignition during the propellant's expected useful life....
EXPLANATION:As nitrate ester-based propellants decompose, they release nitrogen oxides. If the nitrogen oxides are left free to react in the propellant, they can react with the nitrateester, 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. 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. At this point self-heating of the propellant can occur unabated. Once begun, the self-heating may become sufficient to cause auto ignition
An idea of why gunpowder has an unpredictable shelf life can be found in this post
Green corrosion on the inside of loaded ammo
https://www.thehighroad.org/index.p...de-of-loaded-ammo.898092/page-2#post-12128069
@brickeyee
30 Nov 2021
Green is usually copper corrosion.
Bullet jackets (AKA 'gilding metal') are NOT the exact same materiel as brass cases.
There is significantly more copper in the bullet jackets.
The slightest moisture (or other corrosive material) will create a primitive battery with
tiny amounts of current flowing between the different alloys.
The acids used to make nitrocellulose (nitric and sulfuric) are never completely removed.
The tiny amounts remaining are one of the things that determines the lifetime of the nitrocellulose.Wartime production often is left 'dirtier' than ammunition intended for long term storage. Why waste expensive solvents when the stuff is very likely to be consumed within a shorter period.
Long term storage of nitrocellulose powder is done under water.
Radford Army Ammunition Plant was a primary nitrocellulose facility built in the 1940s to support the war effort.
Way back in the early 1980s you could still see the outlines of the wooden buildings used for long term storage of nitrocellulose.
Each was a lightly built 'log cabin' style of constriction with a basement 'swimming pool' to hold water.
The partially completed powder was placed in the basement room, and then submerged in water.
It was dangerous work..
Occasional explosions occurred all the way into the early 1988s from reprocessing.
The old stuff was around 25% nitrocellulose.
It was reprocessed to far higher level (closer to the mid 90%) to make solid rocket motors.
Ejection seats used those rocket motors.
As an EE I had a few contract jobs to try and measure, and minimize, the explosion hazard.
A 'cake' of 90+% nitrocellulose was about 16 inches in diameter and 8 inches thick.
I do not remember the exact weight, but it was pushing near 100 pounds.
We developed some measurement techniques that allowed for easier monitoring of the purity and relative danger.
There was not a lot left of the truck or driver when one went off accidentally during transport from one part of the factory to another.
You could hear the occasional boom in Blacksburg at Virginia Tech, a couple mountain ridges away.
Is sounded like remote thunder.
My pager would go off a few minutes later.
Time to go and figure out what the H happened.
Gunpowder can still be bad, and yet not be fuming. As the gunpowder grains break down, the physical deterioration is uneven. That affects the burn rate as the gunpowder grain burn rate is based on predictable shapes and chemistry. Burn rate instability is a catchall term, it was explained to me that irregular shape and chemistry cause conflicting pressure waves, even down to the level of a single powder grain. Over time the pressure curve of old gunpowder will increase. And yet the gunpowder will not smell bitter and still looks good. So the occasional overpressure condition is something to watch out for.
positive indications of bad gunpowder
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I loaded this ammunition with new IMR 4895. Give it a couple of decades, and the case necks are cracking
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I purchased kegs of surplus 4895 from vendor on Commercial Row at Camp Perry. I did not know pulled powders being sold were infact deemed to dangerous to shoot or store by Ammunition Technicians, and it is probably the vendors did not know, and it is certain, they did not want to know. I heavily tested these lots and then went and shot them in matches in my 308 Win. One lot gave strange retorts. More of a ping than a bang, and I had sticky extraction. Mentioning this to a Naval Insensitive Munitions expert brought me on the path to enlightenment. Like everyone else, I had read in the popular press that gunpowder is virtually immortal, and if it fails, it fails benignly. If wishes were fishes the boat would be full.
That particular lot shot well out to 600 yards, but in time, case neck cracks developed, and that is when I really figured out, that pulled surplus IMR 4895 was bad. Firstly excessive numbers of case necks cracked on firing, and then case necks cracked in the can on loaded ammunition. Bummer, ruined good LC cases.
It is worth understanding that the old surplus on the market place was inspected by an ammunition technician and removed from inventory because the stuff was too dangerous to store, and too dangerous to issue. Ignorant Americans don’t know any better, and buy the stuff. And they don’t understand why velocities are so high, or why they are having pressure issues. Every so often someone blows up a pistol or rifle.
Take a look at these videos. The high velocities are not because the Turks made a magical gunpowder that pushed bullets fast with a low pressure. The high velocities these shooters are measuring are evidence of high combustion pressures due to deteriorated gunpowder.
Turkish 8mm Mauser Muzzle Velocity: The Fastest 7.92x57 Ever?
Ammunition Evaluation: 1941 Turkish 8mm Mauser
At ten minutes 44 seconds, you see the stock cracked from firing this ammunition!
Ian Rants About Dumb Ammo Purchasing Decisions
The first time was a couple of weeks ago when my oldest Son and Grandson came over to load. It was a plastic bottle of VV powder that had been opened and was less than 20 years old. He says that it was stored in a controlled environment and had never been out of the house. You could see red dust when you squeezed the plastic bottle and it had a very strong Ammonia smell. Unopened cans of the same powder of the same age and storage conditions smelled and looked fine.
