Reloading & Humidity

[gatorbone]

In my limited experience, I've never seen any discussions concerning open powder supply (while reloading) and the ambient relative humidity. I live in botanical zone 8b (North Eastern Fl.) and sometimes the rh is equivalent to a bowl of hot mashed potatoes. I don't know how hygroscopic smokeless powder is but it seems that one shouldn't open the powder in these conditions. And even if moisture is absorbed, what is the result?

[PhillipM]

In my limited experience, I've never seen any discussions concerning open powder supply (while reloading) and the ambient relative humidity. I live in botanical zone 8b (North Eastern Fl.) and sometimes the rh is equivalent to a bowl of hot mashed potatoes. I don't know how hygroscopic smokeless powder is but it seems that one shouldn't open the powder in these conditions. And even if moisture is absorbed, what is the result?

I'm in the same zone as you and have shot powder over 10 years old with satisfactory results, however, I keep it in my air conditioned home where the humidity is much lower than outside. I would not keep it in a garage or shed.

[Tuna]

Gun powder does not absorb water. During WW2 the powder used for the military was stored outside in huge piles. BUT if confined say in a case and water gets into it, the water will begin to disintegrate the powder into a mush over time and that will change the composition of the powder over time. But what humidity is in the air should not affect it.

[gatorbone]

Good to know. I keep all of the powder & primers in air tight ammo cans for long term storage so they are not exposed.

[joem]

I've been told that the powder is coated to prevent moisture from being absorbed.

[psteinmayer]

Military cartridges have sealed primers, and in some cases sealed bullet/cases for this very reason. Moisture, either from emersion or from climate (humidity) is very bad "juju" for cartridges. I've started sealing all of my primers, and in the case of my Match 30-40 loads and Garand loads, I will seal the bullets too!

[m1ashooter]

Houston is a tad bit humid. I only open powder long enough to put in the measure what I'm going to load and then seal it back up.. I store my powder in a closet. I've never not had a reload go bang.

[madsenshooter]

On the other hand, very dry powder burns faster and using a published max load with dessicated powder can cause an overload. I pulled down a 50BMG cartridge my uncle had brought back from gunnery school in WWII. It had sat in my grandmothers knick knack case for over 60yrs. The stick powder was bone dry, and crumbly the inside of the case had turned green. Uncle was a little guy, a belly ball turret gunner on a B-24.

[joem]

All my powder is stored in 50% or less humidity as well as the primers. Loaded ammo is stored in the same manner.

[snakehunter]

In my limited experience, I've never seen any discussions concerning open powder supply (while reloading) and the ambient relative humidity. I live in botanical zone 8b (North Eastern Fl.) and sometimes the rh is equivalent to a bowl of hot mashed potatoes. I don't know how hygroscopic smokeless powder is but it seems that one shouldn't open the powder in these conditions. And even if moisture is absorbed, what is the result?

I don't worry about powder but I do about primers. I keep my primers in the lowest humidity I can manage and sealed in air tight containers.