Life Expectancy of Shotgun Ammunition


Southern Shooter
October 21, 2010, 11:53 PM
I had bought some Winchester and Remington shotgun shells to stash away with my food storage. You know, in case of a rainy day. Anyway, I was told today that even though pistol and rifle shells will keep for a very long time...that those shotgun shells, although kept in a dry and air-conditioned place, would expire and become unstable in 5-10 years. And, that this could cause them to explode or something along those lines when used.

Is this true? How long can you store shotgun shells in a dry, cool location??

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October 21, 2010, 11:58 PM
A really long time. My oldest shells are over 30 years old and I still pull from them for upland game. Folks routinely use shells a lot older than that. If they are stored correctly, ammo life is measured in multiple decades, not mere years.

October 22, 2010, 07:24 AM
I have some 16 gauge ammo from the sixties which shoots just fine. Some are paper hulls which were stored in a closet until the previous owners death--so far all these chamber, fire and extract just fine.

October 22, 2010, 08:47 AM
Todays shotgun shells with the plastic hulls if stored properly will last a lot longer than we will .

October 22, 2010, 08:56 AM
Keep then reasonably temperature controlled and dry and your grandkids will be using them

October 22, 2010, 09:01 AM
Don't believe everything you hear, I've shot 12 ga shells near 50 years old with no problem in my Auto.

October 23, 2010, 09:02 AM
cause them to explode or something along those lines when used.

I though that was the point! :p

October 23, 2010, 09:25 AM
I was at the range last weekend and there were a few empty paper hulls laying around...

October 23, 2010, 03:09 PM
I think the main enemy of plastic shells is sunlight and heat. But even a split hull isn't the end of the world.

October 23, 2010, 06:26 PM
shot some 30 year old shells today....

October 23, 2010, 09:35 PM
If anything happen the ammo will be less powerfull. But that is unlikely. I have personally shot shotgun shells from the fifties any they still work fine. But they will never become unstable. Modern ammo should last a lot longer than the old paper shell that were likely to absorb moisture.

October 23, 2010, 10:53 PM
that those shotgun shells, although kept in a dry and air-conditioned place, would expire and become unstable in 5-10 years

I have access to a gentleman who is an energetics expert. I asked him about smokeless powder lifetime. The whole topic is a subset of “Insensitive Munitions”. A term you can Google and find bits and pieces in the public domain.

Smokeless propellants are used in more applications that just cartridges. Rocket motors, explosive warheads, all use smokeless propellants.

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. The hotter it is, the faster it goes. 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 eat up the nitric acid. The stabilizers get consumed over time.

Exposing powder to high temperatures for extended periods of time is bad. Heat accelerates the reduction-oxidation process.

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

The expert said that Navy powders are initially tested at 10 years. They put a litmus 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 when it was made.

The Army scraps by clock time. Double based powders are scrapped at 20 years, single based 45 years.

A few years ago TALON released tons of demilled military powders. That stuff was at the end of its service life. Half of my surplus 4895 powders went bad. One keg turned red and was outgassing and it was poured out on the lawn. About 8 pounds did not turn red, but went bad in the case.

First indications that I had a problem were that I had a lot of split case necks on fired cartridges. Then case necks started to crack on unfired 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 in cases that did not have case neck cracks. I shot some exceptional scores with the stuff at 600 yards with 168 Match bullets. I had "funny" retorts on some rounds. The expert said as the surface of gun powder changes, burn rates are affected.

When the burn rate has been changed, you can have pressure spikes due to irregular ignition. Also, old double based powder has a sensitized surface due to nitroglycerine migration to the surface. This will spike initial burn rate even though the nitroglycerine/ nitrocellulose content of the powder has decreased in time. This may have caused a few blowups with old surplus ammunition.

I was told that when enough nitric acid is released, the powder will spontaneously combust. The expert diagramed the chemical reaction and hot spots can develop as energy is released. As the Military is extremely scandal sensitive, they won’t tell anyone that big bunkers have blown up, but they have. Ammunition depots go Kaboom all the time due to old ammunition spontaneously combusting. You can Google this and find incident reports in the literature. But you won’t find mention of some of the American ammunition incidents that this expert investigated. We Googled one incident he wrote a report on and found nothing in the public domain.

Water is bad for smokeless gun powders as it damages the powder surface and wicks NG to the surface. Even through age is reducing the total energy content of the powder , wicking NG to the surface will increase the initial burn rate of the propellant, which has lead to pressure spikes.

Primers evidentially have an indefinite shelf life. Assuming the primers were not baked in an oven, soaked in penetrating oil, or the cups corroded, primers will outlast powder.

For more detailed study check these references:

October 23, 2010, 11:39 PM
Slamfire... wow :).

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