Question about cleaning and polishing brass. I've been using a dry tumbler with walnut shells and occasionally some liquid polishing. I have great results but recently noticed some not so clean brass after tumbling. The left and right are what looks like heavy carbon or fouling, any tricks for polishing?
The center has what looks like rust or the removal of the brass layer. These were picked up from an outdoor range.
No damage to the case, no cracks and the finish is smooth to touch. Curious if there is anything I can do to bring out the finish or should I just use them

Test
The center has what looks like rust or the removal of the brass layer. These were picked up from an outdoor range.
No damage to the case, no cracks and the finish is smooth to touch. Curious if there is anything I can do to bring out the finish or should I just use them

Test