sonic
I use an ultrasonic cleaner that I bought from Harbor Freight. There are a number of formula on the Internet for safe cleaning solutions.
I buy mine. I use a concentrate, "Aqua Clean" marketed by Shooter's Choice. It is non-toxic, biodegradable, etc......and it works. Midway sells it online.
Soap and water will work. Moose milk will work. Vinegar and water will work.
Pete