It's more a personal thing , if anything I've read it hampers obturation. Plus some have found excessively clean case mouths may lead to large ES's , which apparently, is why some use graphite .Does shinier brass shoot better
I gave up on polishing cases a while back , I simply decap and follow this with a ten minute cycle in the US . In the main thats to remove dirt and residual lube to stop the cases slipping on the annealer wheels and to prevent dirt being introduced into the dies .
I now work on evidence based reloading , a process needs to show benefits to be included . Hence , like Muir , my tumbler stands idle .
Basically , if you like shiny cases , enjoy . We all have a different take .





