Do you have to recalibrate your powder thrower when coming back to load after a week?

[LSP972]

I had a measure full of powder soak up moisture to the point of the water being noticeable when handling the powder (detailed in a previous thread). Still not 100% sure what caused the weird weather pattern in my basement while I was gone that resulted in this, but I now check my powder measure every time I sit down at the press

I learned that, the hard way, when I first began loading with an RCBS Jr, single stage press and their powder measure. Ambient moisture is a real bad thing for your powder, even if you keep the hopper lid in place.

Which is why, ever since I've had my own crib after getting out of the army, my reloading gear has stayed in the climate-controlled living space.

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[Slavex]

my basement is climate controlled but something weird happened when I was out of country. No idea what, but the crack in my powder measure allowed moisture to suck up into the powder. Now when I go away I empty it.

[John Hearne]

I don't keep powder in the press except when I'm reloading, that way the powder is not exposed to environmental vagaries. Because the cost is so low and the consequences so high, before I start to load, I'll do 10 throws, weigh it and divide by 10 to make sure it's where it needs to be. I've never had anything resembling a major (or even minor) shift but I like the peace of mind.

[1slow]

I always individually throw and weigh 3 + charges in the beginning of a loading session. Dillon 550, 650,1050.

[Desertrat]

The correct answer is "sometimes".....depends on powder type, humidity, heat....etc. That has been my experience after reloading
for almost 50 years.