I don't normally clean or polish my Brass.

If I Full-Length Resize cases, I will put them in my Lyman vibrating tumbler with walnut shell medium, for a few hours, to clean lubricant off of the cases.

Ammo that I shoot in bolt guns is usually just Neck-Sized. I put a little case lube on the necks, prior to neck-sizing, and wipe it off with an old towel, before priming. For Neck-Sizing .30-40 cases, I use a Lee Collet Die in 7.5X55mm Swiss and don't bother with any lube.

Sometimes, I clean the inside of rifle case necks with a small bristle brush and mica dust. I have an old 'Bonanza' plastic 'doodad' screwed to my Press Stand. It holds several diameters of upright brushes in a hopper of mica.

I clean Primer pockets with a RCBS hand tool.

I think shiny Brass may draw enemy fire!  ;)