Get a large wide mouthed plastic bottle with a fitting cap. Put the brass in. Add 2 table spoons of vinegar, a shot of dish soap. Fill with water to almost full. Shake for a few minutes. Pour out soapy water. Add clean fresh water. Replace cap. Shake for a bit. Repeat till the water stays clean with no soap in it. Then pour the brass onto a towel. Let it dry for a while. If you put it out in the sun they will dry faster.
I did this for year before I got a tumbler.
No matter how many times you do it and nothing happens it only takes something going wrong one time to kill you.