Silicon Carbide 80 5lb

You could but I wouldn't recommend it. The Lot O Tumbler works a lot like the vibratory tumblers so the coarse grit might work too quickly and harm your barrel. We hear of people doing a coarse step in their rotary tumbler to break the rocks down and smooth them out and then jumping to the Lot O Tumbler. Otherwise it's powerful enough that you could skip the coarse step entirely and start with the medium in the Lot O.

We'd need more information about what machine you have and what you are doing. But this is 80 grit for making a slurry. One thing to keep in mind that coarser grit will also wear down your pan.