I use this recipe I found on 6mmbr.com with a ultrasonic cleaner.
"CHEAP and CLEAN
24 minutes - 50% Vinegar + 1 Drop Dish Soap per 8 ounces water
480 seconds - Baking Soda (BS) in water (1 grain BS per ounce of water)
480 seconds - Hot Water
480 seconds - Distilled Water
Total: 48 minutes
Cost: Less than $2.00 per gallon".
I shortened the first stage to 8 minutes and I exclude the distilled water stage.
I found the whole process impractical with small batches of 20-60 38 spl cases.
After cleaning I dry the cases with a hair drier for two or three minutes.
If I was a mass reloader I would definitely make a rotary tumbler and use SS pins.
I like to see the clean insides of my cases, although this process will not remove the gunpowder tarnishing on the outside of most cases, but at least their squeaky clean inside and out.
This is the address to the webpage: http://www.6mmbr.com/ultrasonic.html
It's really informative.
.357MAN