Case Tumbling
Also: Wet Tumbling · Dry Tumbling
Cleaning fired brass in a tumbler, either wet with stainless pins and water or dry with a granular media, to remove fouling and residue.
Case tumbling cleans fired brass by agitating it inside a rotating or vibrating tumbler so an abrasive carries away carbon and tarnish. Dry tumbling uses a granular media such as crushed walnut or corncob and polishes the outside of the case, while wet tumbling uses water, a little cleaning solution, and stainless steel pins that scrub the inside as well.
Tumbling is a routine step in reloading, both to prepare cases for handling and to strip residual case lube after sizing. Wet tumbling with pins also reaches inside the primer pocket and the case neck, leaving brass noticeably cleaner than dry media alone.