Good advice. Some powder, I saw Bullseye once, actually have the chemistry begin to "eat" into the plastic of the Lyman 55 reservoir, and simultaneously cake up solid. The friend had about 3 inches or so in the powder measure that had been left for probably 2-4 weeks, and that reservoir was shot; not all the powder could be removed, and there were little craters all around the interior where the powder etched into the plastic. Since I started reloading, I never left powder in the measures, but that display made my habit somewhat rigid. Whenever I'm tired, or want to get done and to bed, that image always comes to mind, like it was yesterday...