I should also add that STM does the best job of cleaning brass. Takes a bit more time when you include drying, but if you like clean brass there is no better way.
If you buy the proper tumbler and media you will never go back to the 1/2 *** cleaning of corn cob, walnut shells, or ultrasonic. I have all those dusty machines to prove it.
Stainless media is the way to go and it cleans in 4 hrs. I recommend buying from STM , that is where I got mine.
+1 on using SS media. I cleaned brass for 25 years with corn cob media but once I got the SS and (as mentioned above) the "right" tumbler for it, nothing compares or does a better job. It will be clean as new inside and out primer pockets and all.
And I 2nd the fact to buy from STM. Great people to work with.
All I can say is WOW does it work GOOD! I ran some once fired brass thru for 3 hours it looks better than new, inside and out and primer pockets. Then I found the worst looking brass I have, it has sat in my garage for 20 years and was very tarnished, I ran it for 4 hours and they look like new
I got the media from STM but I cheaped out and got the tumbler at Harbor Freight