I use a walnut bird bedding(IIRC). Very small grind, there is a little dust but I run mine in the house with the lid off and it has never been a big deal. The corn bedding i was findn was all too large and made for a PITA to remove from 22 cal brass.
ETA: I just checked my media and the kay cob is what I have that gets stuck in the 22cal cases. I think it will work good for larger bore but IDK. what I switched to is called Kaytee walnut pet bird litter. 7lb bag was like $8 maybe.
I use the same kaytee stuff. Works pretty good, been running the same tumbler full for a few years. I ran dryer sheets in it in the beginning now its dust free.