Maybe I'm being unrealistic...Here's a pic of three cartridges...
First is typical before being shot...Second is after 'vibrating' all night with crushed walnut shells...Third is spin-polished with Nevr-Dull...
I don't really expect them to be bright & shiny like the third...But is the second about the best I can expect???
(All are 5.56 military cases formed to 30 Mauser)