Most reloaders use vibratory case tumblers, to clean up the fired cartridge cases before reuse. Among the reasons for doing so, is to ensure that you don’t scratch up your reloading dies from sand and grit on the cases. Another reason is to have brass that will feed well in your gun, and is nice to look at.
I actually use not one, but two tumblers.
I use a Dillon CV-2001 for cleaning the used cases. I add around 5 kg of cases, use crushed corncob media with Dillon’s polish, and tumble the cases for 3 hours. They come out nice and shiny from that.
After I’ve loaded the ammo, it gets tumbled again, to remove the case lube. I use a different tumbler for that, a small one from Graf
So why use two tumblers? Part of it is that the cleaning media I use for the loaded rounds lasts a lot longer, and doesn’t become as dusty as the media used for cleaning. It also means I can use Dillon’s polish on the dirty cases, even if I don’t want to use it on the loaded rounds.