Genuinely by hand! At work I have access to 5ltr containers, so the brass went in with water just covering the brass, washing up liquid and citric acid, for around an hour, I manually “tumbled” the container every 15 mins for 4-5 minutes.
I’m now looking at a solution to shining them up, I’ve purchased Lee’s shell holder drill attachment for my cordless but yet to decide on what to use, I’ve seen a few 0000 steel wool comments.