Moral of this story is if you are tumbling different cartridges, make sure one wont snugly fit inside the other.
I would amend this slightly. When tumbling different cases, make sure one won't fit inside the other AT ALL!!!
Because if one will, the media will jam in there and make sure its "snug".
Also be aware that if PART of the case will fit in another, they can be jammed together too. Bottle necked rifle brass can be "capped" with 9mm and larger pistol cases. and surprisingly tightly too!