Home Forums Reloading Big Game Rifles Powder absorbing moisture

I am sure many of you have seen the warning on powder not to leave it in your measure, always store it in it's original container.

About 6 weeks ago I was working up some loads for my .308 with Varget. Got up to 2800 velocity with 46gr , got interrupted and didn't get back to loading for about 6 weeks. Started again with the powder left in the measure and chrono'd 2675?? WTF?? got some fresh powder out of a 8lb keg, same load back to 2800+.

As a experiment I weighed out 46 grains of varget and left it in the scale pan for a week...it now weighed 48.5 gr It has been pretty humid lately especially in my basement and I am pretty confident the powder absorbed moisture. If the powder in my measure absorbed this much moisture it would of in effect reduced my charge of 46 gr. by 2.5 gr. Hence the lower velocity.

Something to think about.

Lefty C

Curious: Did you weigh each charge through your measure during these events, or did (do) you just drop from the measure into the case?

MZ

Through the measure to the scale pan, top off with trickler to get exact weight. Redding balance beam scale.

LC

Thanks. Might be fun to see the results if you did pure volumetric throws, weighing them afterwards just for the comparison.

Despite the lack rain in most parts of Colorado this summer, it was exceptionally humid air for 6 weeks or so........weird. If powder can absorb that much moisture in Colorado, think what it must be like in the south!
Sheesh.


Casey

alpine,

Yea, More humid than I remember for a lot of years. Afternoon storms would roll in and at 7600' we are literally in a cloud, and could stay there till morning unless a good wind came up. Very little wind this summer also. Up on top of the ridge where the house is it is usually so windy we have to tie our grill, chairs, etc. down or they will be blown off the deck. At least everything is green and don't have to worry about fire for now.

LC