Powder loosing temp stability over time?

[jrock]

I pulled an old, half full can of Varget (6+ years) off the shelf to start working up loads for a new gun. I found that the powder has some crazy velocity spreads with temperatures changes. I've tested two different powder charges from 70 degrees to 98 degrees and both show the same rate of change of 3 fps per degree! This is the highest rage of change I have seen in my limited life of reloading. Varget is an extreme line of powder so is supposed to be somewhat temperature stable. Can powders loose their temperature resistant characteristics over time?

 

[Dosh]

Some powders lose a little once opened depending on storage conditions. Many report no effects on 20+ year old powders. Obviously a large difference in observations. Perhaps you could use the old Varget in a plinker i.e. AR.

 

[jrock]

With velocity spreads like that, short range hunting or paper punch is about all its good for. I could have a 60 fps spread between and mid day. I wish I could find more Varget to test on a new can.