All gunpowder deteriorates. Gunpowder is either nitrocellulose, mixed in with a lot of chemicals, or nitrocellulose and nitroglycerine, mixed in with a lot of chemicals. The shooting community does not want to believe this, has been told otherwise in gun magazines, but, ignoring what the shooting community desires, gunpowder follows the second law of thermodynamics. It is a high energy compound that is breaking down to a low energy compound.
It is probably confirmation bias, but it seems that I am reading more and more reports of Vihtavuori gunpowders breaking down. It does seem interesting that their lifetime is getting close to 25 years, which is beyond the reasonable shelf life for double based, but not beyond the shelf life of single based powders: 45 years. All the Vihtavuori stories I have found deal with single based powders. Which shows that the lifetime of gunpowders is rather unpredictable. This is a basic issue that allows the shooting community to pretend gunpowder lasts forever. Some stocks of gunpowder last much longer than expected. The ones that went bad within 20 years, they just ignore. Also, if it has not happened to the skeptics, then it cannot happen, or did not happen, or both.
When gunpowders break down they release nitric acid gas. Nitric acid gas will corrode copper and brass. Probably a lot more things as nitric acid is very reactive. These bullets were pulled from very old US surplus ammunition, I don't remember how old.
These are 1960's factory Norma ammunition that went bad in the case. The guy who posted this, these cartridges had been stored in his father's house, if I remember right. The corrosion is due to nitric acid gas.
Old gunpowder has, and will, blow up firearms. What happens is a phenomena called burn rate instability. It is a catch all term. Gunpowder has been engineered for a consistent burn. The shape, the geometry are all carefully engineered into the final product. When gunpowder deteriorates, it deteriorates unevenly. The grain changes shape, instead of a nice smooth tube, (for example) now the tube is thinner in places. When it burns, the pressure is inconsistent because parts of the tube are burning faster, other slower. These pressure waves conflict. If there is dust in there, the surface area is huge. If it is a double based powder, the nitroglycerine wicks its way to the surface, which will spike the pressure curve.
I have a number of accounts of military surplus ammunition blowing up rifles. The owners and the commentators don't know, and don't want to know about old ammunition and pressure problems, so the suggested reasons why the gun blew up can be quite fantastical. Often racist.
Here are some other threads, the first one has great pictures of the effects of deterioration.
Has anyone else had Vihtavuori N140 corrode in loaded ammo?
http://www.falfiles.com/forums...thread.php?p=3745264
Bad N140
http://thefiringline.com/forum...old+gunpowder&page=3
Of particular interest to me was the link to the thread on N140. In the early 1990's, my dad got a 1/4 lb free sample container of N140 at Camp Perry, and gave half of it to me. That's about 20 rounds worth in .308; not enough to do serious load development with. I put it in a plastic bottle with a plated and painted steel cap with cardboard seal disc. I left it at the back of a high shelf in the basement where it was out of sight and soon out of mind. Some time later I bought a full pound of N140 to experiment with, but that original 1/4 lb continued to sit.
I finally re-encountered the bottle during some cleaning out activity. It looked like this:
the lid out. Rinse water put over it poured out yellow. At that point I cut the container open and buried the wet mass under the compost heap to let nature take its course.
Interestingly, the remaining 1/8 lb still at my father's place (also untouched) appeared to be in fine condition in it's original container. Shaking some out onto a white sheet of paper to look for traces of red dust showed no signs of any. Odor was normal. Nonetheless, with only that small amount left, we scattered it over the yard.The powder in it was not powder any longer. The grains were all stuck together. That was the result of the lid seal failing and letting humidity in. The acid fumes corroded
The final lesson, is that old gunpowder will burn your house down. If you ever see a jug gunpowder outgassing like this, get it out of the house and dispose of it.:
Vihtavuori N150 gone bad
http://m14forum.com/ammunition...i-n150-gone-bad.html
Well I was going to work up a load today with Vihtavuori N150, but when I opened the jug, whew, what an odor!!! Then gold colored fumes started coming out of the jug. Don't know how old this jug is, it was given to me about a year ago.
Tried to get a good picture of the fumes, but the wind kept blowing it around.
Anyways, keep an eye on your powder.
When gunpowder deteriorates, it heats up. In quantity, definitely eight pound jug size, maybe one pound jug size, the stuff will catch on fire. Gunpowder in small arms cases is hard to auto combust because the shell casing draws out heat. The US Army believes that nothing smaller than a five inch shell will auto combust, due to the cartridge walls drawing out the heat, but an Insensitive Munitions Expert I met, said that was all bunk.
Recently I looked at the definition of Confirmation Bias in the book, "You are not so Smart"
The Misconception:
Your opinions are the result of years of rational, objective analysis.
The Truth: Your opinions are the result of years of paying attention to information that confirmed what you believed, while ignoring information that challenged your preconceived notions.
Reloaders want their ammunition and gunpowder to last forever, so they ignore any evidence otherwise. If you search this site, you will find posts, about gunpowder lifetime, that obey Confirmation Bias. You will read posters discussing their pre WW2 gunpowders they have, or used, or bragging about the massive quantities of old gunpowder they have, and that proves to them that gunpowder lasts forever. On many forums you will run into crazy coots who have been hoarding gunpowder. They store the stuff in the house, and one day, their hoard of WW2 gunpowder will catch on fire, and burn them alive in their sleep.
The coots don't believe this, and the shooting community generally believes gunpowder is immortal. Shooters only believe what they want to believe, and they want to believe that their stash of gunpowder and ammunition will last forever.
