I commandeered the Ulrasonic jewelry cleaner someone gave my wife for Christmas. It has been in the box untouched for a month so fair game I say!
It will hold 75-100 9mm de-primed and has a basket they sit in. Couple drops of dish soap and a pinch of Lemi Shine dishwasher stuff in the water and let it run. The timer goes for 8 minutes max so you have to punch the button about 3 times as you go along. Rinse them off good and you can feel all the oil and soot are gone. It takes out all the carbon, they are not real super shiny but they are clean.
I lay them out to dry on newspaper since it is winter and with the furnace cycling does not take long. Summertime, I may set them out in the sun.