Worrying too much about shiny bores is what would be wrong, in my opinion. Each shot cup melts a little from friction each time you fire the gun and traps the burnt powder in the softened plastic. But, even after you listen to several cleaning opinions from different members, when you fire the first RST you will get right back to the same look down the bores that you had before you started all the cleaning. If you don't see a noticeable change in hits or misses, or changes in patterns, keep firing, enjoy yourself and worry less about having factory shiny bores at the end of each day. When you go home push out the heavy gunk, stand the shotgun on it's muzzle and go watch some TV and have a drink.
Bill