Removing powder from dispenser for storage?

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I would put the excess back in the original jug. I think light and air are the enemies of smokeless powder (other than politicians!). I think it can also discolor the plastic tube in the dispenser.

How long between uses, if only a day or two it won't matter, week or more put back in original container to keep the powder and the reloading area safe.

The powder over long periods can also degrade the plastic in the hopper. I try to put it back after every loading session.

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I know winchester superhandicap powder caused my hornady 366 plastic tubes to swell....

It seems to be good practice to return excess powder to the original container after each loading session. After forty years of weekly use, my RCBS powder measure is still in service with only minor etching on the inside of the plastic tube.

Beeser,
Actually, it does matter, especially if one lives in a humid climate (it may not affect you in Arizona). All gunpowder is hydrophyllic (literally 'water loving' and will soak up humidity). Anyone living in a humid climate can test this the next time they open a new can of powder for a loading secession. Leave the powder in the reservior after you're done. The next time the same charge is dropped, it will weigh more.

I don't know how much this affects accuracy, but logically, the effect is greater and more significant at longer distances. I return powder to its container after each loading secession. If I know I'm not going to be using a powder for awhile, I will also add tape around the lid to help keep moisture out. I also have to put rice in my salt as does everyone else in the south. dipnet