Well I just dispatched the shell casings from 18 moon clips, and when I finished my hands were black. I grip the moon clip in my left hand, and twist the shell off with a tool in my right hand. If the ends of the cylinder get dirty, why not the moon clip? It's laying directly on the cylinder.Moonclips get dirty???? I might have run into minor carbon deposit or dust that wipes off with a rag, but have never seen anything that requires any real cleaning.