How many do you shoot for load testing?

[82boy]

Hey 82Guy - if you're loading onsite, would humidity be a concern? I mean, wouldn't the propellant absorb humidity miosture & change the burn rate & ballistics of it?

No not at all.

Anytime you open a can of powder it is going to change to the atmosphere, no matter if it is in your house, or at the range. The change is not a concern, but powder will weight heavier in the morning, and as the day goes on it will weight lighter, even in your AC/Heated house. The powder goes throught this cycle over an over. I have shot powder that was from a 50lbs barrel, (Old 8208 pull down powder.) that was placed into 8 lbs jugs, (some 15 years ago.) and it shoots the same today as it did 15-20 years ago.