There are people on YouTube that test all the various ultrasonic cleaners.

For shotgun actions you don’t need a multiple wave source ultrasonic cleaner.

I like the heater, and I just run multiple cycles changing the soapy water.

They will clean an action cleaner than you want.

You will have to lubricate and protect every surface in the entire action to keep it from rusting in any kind of humidity. And I’m talking hours, not days.

Out there doing it best I can.