I agree with canvasback about the Cerakote. The blemishes remind me of a blue job carried out in winter(poor) light. The barrels can be de-greased with acetone after disassembly and the barrels re-blued without re-polishing. A couple passes of slow rust bluing, carefully done in good light should do the job, without a lot of time or expense. Polishing is what takes the most time and where the most likelihood of damage lies.
Mike