I also use rice just plain old white rice. There is one disadvantage to it well maybe you would say two really. If you tumble before you deprime it will break decapping pins when they hit a kernel in the flash hole. After you deprime some kernels will be caught in the flash hole but a little flat screw driver removes them.
I started with corn cob media and didn't like the dust and it would hang up in 224 and 6mm case mouths.
Al