Dahermit - sorry my fingers don't work right - but I'll blame the keyboard. Tap the gun on the side of the container lightly or get one of those battery operated vibrators & attach it. I keep a spare plastic 'collector' bin to dump excess into by rapping the barrel. The gun can barf and give you a heavy coat.
I don't think freeze drying the powder will work, H2O attaches to the powder. Vacuum drying might.