This is probably old hat to those of you who have been reloading metallic cartridges for many years. For those of you new to the hobby, like myself, please learn from my dumb mistake.
I bought a RCBS Chargemaster a few months ago. I was loading some batches of 9mm with Alliant's Power Pistol over several weeks. Being the lazy person I am, I left the pound of powder in the plastic hopper. This was over a timeframe of several weeks. When I decided to empty the pistol powder out to put in some rifle powder for my .243, the Power Pistol was melted into the clear plastic tube and plastic hopper! ***?
After an hour or so of scrubbing with my fingernails, toothpicks, and Hoppes soaked Q-tips, I managed to get all the caked on powder cleaned out. But by now the damage was done. The clear plastic tube and hopper is now permanently etched. Functional yes, but no longer looking like new.
After reading through the RCBS Chargemaster manual I came across this: "DO NOT store powder in the unit after the reloading session. Over time the powder will corrode the powder hopper." Searches on the internet found another reloader having this issue with Bullseye powder.
Lesson learned for me. I'm dumping the powder out of the hopper after my reloading session.