Thanks for the compliments on the photo Jack. If it turned out arty I can assure you it's totally accidental. I'm afraid creativity is not one of my strong points!
I'm interested to see if anyone sees a problem with dunking the barrel in the electrolysis bath. I'm thinking the bore won't be affected because it was still oiled up and there is zero rust in there. I thought that electrolysis only worked on rusted surfaces???
It might etch the bore slightly; depends on what current is run, and how long it's left in the bath. Your query has sent me off looking at scientific papers relevant to this type of electrolysis...
I get the impression that there are both direct electrochemical [reduction of rust from Fe
20
3, but not all the way to Iron metal] and physical [from Oxygen gas generation on the workpiece/cathode surface] processes in play here. The gas bubbles will physically loosen the rust from the surface.
This gas generation occurs over the entire surface of the workpiece, but
not uniformly - the closest bits to the anode will have the highest rate.