I use them in a wet tumbler and the cases come out looking like factory new inside and out. I decap before putting them in and the primer cups and flash holes also look like they have never been used.
The tumbler is a "Thumblers Tumbler Model B". Add 5 lb of pins, one gallon of water, 1 tablespoon of cascade, and 1 tea spoon of a lemon cleaner. I tumble for 4 hours then spread them out on a pizza pan lined with two layers of paper towels and dry in the oven on the lowest setting (about 1.5 hours)
When they are dry I give them a quick shot of Remington dry lube. That helps them go through the dies easy.
The cartridges sure look pretty when you finish. You can't tell them from brand new.
P.S. The wet tumbler gets rid of the dirt and dust and noise.