I have pulled LC 14 LR .308 brass I've deprimed. I've used corn cob and now walnut hull, over 5 hours tumbling. These spots still remain and I'd like a nice shine. What could be added to produce the shine, and is that something that won't need removed before firing, don't want very slick cases do I? Using now 18/40 med walnut and have fine 35/60 if needed. What removes these spots, more tumbler time or different media or additive. This is my first try polishing brass.