I often do up to ~500 9mm bullets at a time in a quart yogurt tub, and pile them up on the baking tray as deep as they need to go.
It takes 15 seconds of shaking; putting them in a tumbler is not easier or faster, it's just a way to the cheap junk HF powder to stick. Adding air soft pellets is dumb too; I don't recommend anyone do that. If you haven't tried a good high quality powder, you don't know what you're missing here; it does make a difference.
Also, it's powder, not paint.
