A little water in your corn cob or walnut cleaning media cures the static cling and walnut dusting. Try half an ounce of water per quart or liter of media for a start, and another half ounce if it's still clinging. Don't overdo it, and don't add water if the cases are in. Let your tumbler or vibrator run for 5 - 10 minutes before you add cases, or you'll have a wet glob inside a case. I got this tip from a Mic McPherson article.