I have some old 30-06 brass that is really stained black and doesn't seem to clean up very well with the walnut stuff in my vibratory case cleaner. I tried spinning one in my hands with some fine steel wool and it seemed to clean up pretty shiny with not much effort. Since others have gone to using steel pins to clean brass, I wondered why steel wool is not used? Does it cause fine scratches that result in case failure? Or embed pieces of steel in the case wall that caused problems?