ATTABOY for asking !
Not dumb question... if you don't know...asking is smart !
Brass bore brushes are made to clean inside barrel and cylinder , just add a little solvent , CLP , WD40 or oil depending on how dirty / fouled the barrel is . Cleaner and lubricants make the cleaning job easier .
Don't use stainless steel brushes , if they still make them ... I think the harder SS brush might do damage so I never tried them ... brass brushes are fine .
Gary
I think bronze bore brushes are a much better approach to gun cleaning. A brass brush would leave tracks all over the blue finish.