Just for the heck of it, I contacted the manufacturer of the stainless pins and asked about using them dry.

I was told that it doesn't work well because without the liquid to suspend the crap knocked off the cases the entire contents of the tumbler just become a dirty old mess with no way to finally separate all the crap from the good stuff. This makes all kinds of sense.

I suppose it would be possible to do a final liquid rinse after tumbling, but in that case we might as well have done it wet as recommended from the get-go.

Never thought about it before, but I guess the usual dry media like hulls or whatever sorta latch onto the dirt and hang onto it, thus eventually requiring replacement.

As far as POLISHING the brass, I can see the pins doing a much superior job as advertised. They are, after all, harder and thereby more agressive.