Why might Avg. Velocity change between reloading sessions?

straightshooter1

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This humidity thing has led me to the tentative conclusion that I will measure and record the humidity of the powder for each reloading session and the date. It I measure one and it’s an outlier, I don’t know what I will do but probably mix it with another pound as above. Putting a “humidity pack” with my powder seems extreme and untested.

Actually, I'd say it has been tested. If you don't know much about Bryan Litz, check out his history (his education and experience is impressive). Here's what he says is one of the thing they do:

 

cas6969

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It would be nice if people would stop making attributions on their respective...
It's kind of like people giving advice based on the notion that everyone is trying to do what they do.
 
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secondofangle2

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Actually, I'd say it has been tested. If you don't know much about Bryan Litz, check out his history (his education and experience is impressive). Here's what he says is one of the thing they do:


I know all about Litz for many years and have read all of his books. I didn't recall seeing that he had done this. Thanks for the link!

He's describing it as an experimental condition in the video. I'd be interested in whether he routinely bothers with humidity packs in each jug of powder.

I see that Boveda "guitar" 70 gram 49% packs are like $4 each on amazon. Maybe I should just be doing this? Try to keep the powder at 50% humidity like it comes from the factory? If it works reliably without complications, it would be way easier than screwing around with Kestrel D2 drops all the darned time.

What's everybody's thoughts on putting a guitar humidity pack directly in your powder?
 
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straightshooter1

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I know all about Litz for many years and have read all of his books. I didn't recall seeing that he had done this. Thanks for the link!

He's describing it as an experimental condition in the video. I'd be interested in whether he routinely bothers with humidity packs in each jug of powder.
If he's not just using such humidity packs, I'd bet he then has a storage space and/or loading room that has controls for the humidity.
 
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Rover31

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Have not read the entire thread so someone may have posted this already.

How did you store the powder between loading sessions?
Humidity can play a role in the velocity.
You powder can gain or lose humidity changing the weight of the charge thus changing the MV.

There are a few recent papers out there on this.
 

frer

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You started with virgin brass which is going to be smallest internal volume that it will ever be. Then you fire formed it and increased the internal volume = lower pressure/lower velocity. Right?

Or were both sessions with virgin brass?