Storing powder

[Shane Lindsey]

When I first started reloading I kept my powders and primers in old 40mm type ammo cans, still do. I lived in southern California and kept them in the garage. They are sealed and water proof. Figured this was good for containing it in case of fire for at least a little while. Now in Virginia, they are in the basement. I too have a dehumidifier in there.

I still use them, but have realized that I need more ammo cans

 

[GLTaylor]

From Hodgdon:
Smokeless Propellant

The main ingredient of smokeless propellant, comprising from about 55% to 90% of the composition, is nitrocellulose. The process of creating nitrocellulose leaves remnant acid in the material. This acid immediately starts decomposing the finished product. Left alone the decomposition will reach the stage where the propellant becomes unstable and self-ignites. This process resulted in massive explosions at U.S. Government arsenals after World War I.

To increase the life of the smokeless propellant, a stabilizing chemical is used. This "stabilizer" reacts with the acid to slow down the decomposition process. However, as the stabilizer reacts with the acid it is consumed. After the stabilizer is totally consumed, the propellant is no longer protected from the internal acid.

The entire stabilizer / decomposition process is a time and temperature function – the higher the temperature, the shorter the safe life of the powder. Even moderate temperature, over extended time, leads to propellant decomposition. As a rule of thumb, any temperature over that which is comfortable to a person is accelerating the decomposition of smokeless propellants.

Under proper storage, modern smokeless powder can last for decades. However, this does not mean the reloader can ignore how the powder is stored, particularly if in an uncontrolled environment such as a garage or storage building.

Thanks Muddy. That's great info!

 

[Pdyson]

I just watched a YouTube video (fortuneCookie45LC) an older gentleman with a pound Of the old WWII 20mm canon powder Bruce Hodgdon's War Surplus (Imr4831). It was the last of the surplus 4831 made in The 1940s and he bought it in 1971 which means the powder was 78years old. He loaded 48gr of powder per a load in the hornady 9th addition manual (pg433) and achieved the exact velocity predicted in the manual. avg 2317 fps ES 34 SD13.
i wouldn't be afraid to pickup old powder at
an estate sale and use it. If the can was in good shape(no rust), and it passed the smell test.