I have a rotary tumbler for cleaning reloading brass. It is a super helpful piece of kit if you run your gun suppressed as your brass gets caked with carbon that is a pain in the ass to tumble clean with corn cob.
I typically use stainless steel pins to do the dirty work. Must tumblers will come with some form of media. You can also get little shards of stainless that you can add to do a better job of cleaning out the primer pockets.
The Firearm Blog did a post on some new porcelain media from Creedmoor Sports that is supposed to be lighter and do a better job of cleaning. I picked up a container of Rods
Optimized for brass .223 caliber and above.
I tumbled around 100 rounds of Federal Gold Medal Match 308 brass in the new media. I would say around 35% had media stuck in the primer pocket that you needed a knife or super small screwdriver to pry out.
Totally sucked and such a waste of time. I dont even think the brass looks as good as it does with stainless. Plus the cleanup with stainless is easier as you can use a magnet.
I would recommend NOT buying the Creedmoor Sports Brass Care Media. The Grass is not greener on the other side, the grass is actually dead.