I discovered on the slide of my Bersa Thunder 40, immediately behind the ejection port, some tiny dots yellowish in color which I thought were some sort of brass particles impact dots. I read that if you use a brass brush and some light cleaner (used some regular spray Remington oil) the bluing may not be damaged.....right.....now the entire part look faded and a touch on the yellowish side in color...I thought they could be brass residual from the cleaner and brass brush..., tried to clean it....still there... I think the steel alloy of the gun itself is a tinge of yellow in color....the spots I saw were scraped bluing not some sort of brass impact. Then I thought...yes brass is softer than steel....but still leather holster can wear bluing in pistols.... So what is the rule?? Brass brushes do ruin bluing after all??? If the bluing is really gone, Bersa bluing is a little more than just a coat of paint in my book. Is my stupid mistake fixable?? At least I learned my lesson on an inexpensive gun.