Powder longevity: Precision

Yoshi · Sep 4, 2018

Does powder lose its consistency over time or can I expect the same results as if I just bought it? Or, can I expect more fliers?

Powder in question is RE15 and it's about 4 years old.

E.Shell · Sep 4, 2018

Properly stored, kept in the proverbial "Cool Dry Place", powder is quite stable and life is indefinite. 4 years is nothing and I have seen old run FGMMs, in the old blue & white box, shoot great (same accuracy and velocity consistency as new ammo) after being around for 10-12 years or more.

Although I cannot speak to the consistency, I've shot milsurp ammo as old as I am with no issues.

TrappedinMD · Sep 4, 2018

I reload pistol ammo with powder that is 30 years old and it runs fine. Proper storage (cool + Dry) is key i believe.

axshon · Sep 4, 2018

Not a chemist (INAC?) but I'm pretty sure most powder has some kind of coating(s). I moved recently and tried not to shake it up too much. I also try to use up what I pour to prevent pouring it many times. It's my personal guidelines, not scientific.

kalister1 · Sep 4, 2018

My Letter to IMR:

Hello;
I have an OLD can of DuPont IMR 3031 Smokeless Powder.
It was used and stored in the original container. I opened it today and it did not smell right and had DUST coming out of the can when poured.
I spread it over my yard.
Can you tell me how old it was? It could have been purchased in the 1980’s?

P82MA26A 1395

Reply:

Not quite 33 years, 11 months and 2 days

Mike Daly

Hodgdon Family of Fine Propellants
Hodgdon Powder Company: The Brand That's True
IMR Legendary Powders
Winchester Smokeless Propellants
GOEX Blackpowder

When did it start going bad?

Seabee · Sep 4, 2018

I recently finished up a can of Unique I bought back in 1975. It looked fine. As long as it isn't clumping/sticking or discolored it should last almost indefinitely if stored properly as stated above.

John from MD · Sep 4, 2018

As long as it is not smelling like acetic acid, doesn't have any red dust and color hasn't lightened, it is usually good to go. I have used surplus 4895 powder over 25 years and it kept up with a new can of H4895 to within a few FPS. As someone stated, keep it cool and dry and it will last a long time.

boule · Sep 10, 2018

The stability of propellants is mainly dependant on the manufacturing process and following the storage conditions. You cannot influence the first part but do a lot about the second one.

During manufacture, cotton (or another source of cellulose) gets turned into guncotton through the application of sulfuric and nitric acid. Later on, the acids are removed during several wash steps and excess water is removed by the application of pressurized alcohol. Depending on the efficacy of this process. small amounts of acids can remain and get carried over into the manufacturing process. This is why further stabilizers are added.
In an absolutely dry state, there would be very little to no chemical reaction. As soon as you add a little bit of humidity to it, decomposition begins and is aided by high temperature. Rapid changes in temperature and humidity add to the decomposition process by imposing physical stress (swelling, size reduction) on the powder grains. Ultimately, you get a sour smelling dust (acetic acid is part of the substances generated).

The interesting question is more or less if your can of propellant is usable or not. Sorry to say, but it is really hard to make a promise on that. If the acid removal was efficient and the can really airtight and never opened and stored in a cool place, you stand a good chance of having a usable powder. Can it be guaranteed? Nope! Check for obvious signs of instability (smell, discoloration, dust) and discard if you find any (1lb of powder, add some Titanium dinitride and light around july 4th). If the powder appears OK, you can try to load and fire a few rounds and check for changes in velocity.

byf43 · Sep 11, 2018

About 3 years ago, I finished using up an opened container of Winchester 571 powder, making some 'magnum' loads for Turkey hunting.

I wish I could get more of it. (It's lonnnnnng since been discontinued.)

Best performing magnum shotgun loads I've ever assembled.

Powder longevity: Precision

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