25 years ago I bought a Dillon vibratory cleaner which I always regarded as being very good at cleaning cases. Then about 10 years ago acting on a tip from a friend I bought an ultrasonic cleaner and use 25% solution of common toilet cleaner (no chlorine!). The stuff is dirt cheap and very effective, about 10 minutes in the machine and the cases look like new. They then get drowned twice in a bucket of water and stood to dry on old newspaper. I use that method on my 38 Spl cases and on rifle cases, especially those used for reduced loads. It is reassuring to be able to see the powder in the bottom of a 30-06, as opposed to looking into a black hole.
9mm and 45 ACP just get the vibe treatment.