My screw mount black paint color skopar 28/3,5 is heavy and suppose this means there is brass beneath. I've used other not mine WA CV lenses (25, 15, and 21 mm); these latter are very light. So I don't think there is brass beneath the paint, screw mount or not. Another possibility may be the interior part barrel is aluminum and the outer is brass. The only way to be sure is waiting the paint is scratched. Who knows?