Is this a smelting pot for melting lead that is sitting under the scale?

its hard to tell by the picture. Lift up the scale and look. Normally it if has been used, there are traces of lead in the tank. Some of the old ones were dippers and others had a pour spout on the end of them.

looks like a sonic cleaner

What with the supply of store bought bullets he has I don't think he casted his own bullets.

I believe that is an autoclave.

I have to agree, it does look like a sonic cleaner.