I see we have some unbelievers here.
This is typical electrolysis tank results. It DOES NOT remove bluing. It removes RUST or iron oxide.
Before
After
Before
After
Before
After
You well remove more bluing with steel wool and oil than with a ET.
No method of rust removal well get into the tiny cracks and clevises that a ET well.
You can build a basic ET for under $20 with you already own a battery charger. By far the best method I have used in forty years.
The next step is a bore cleaning setup with a mall wart for power.