I have a Midway 'vortex' type case cleaner (not really a 'tumbler') and over the years I've tried crushed corn cobs, crushed walnut shells, and glass beads...None seem to get tarnished brass shiny...All they do is clean off the surface dirt...
What do you reloaders use to get nice shiny cases???
I have used Nevr-Dull and shined them individually by hand, but I would rather just chuck them in the 'tumbler' and let it run all night...