Birchwood Casey sells a lead removal cloth that is effective, but will remove blueing. They say it is safe on plastics.
Another possibility is D-Wipe hand towels/D-Lead handsoap by Escatech and available from them, Brownells, DawsonPrecision, MidwayUSA, etc. Given that its ph neutral should be safe on bluing too.
Just some ideas. I like the the Birchwood Casey cloth, never tried the the D-Wipe product but keep meaning to pick some up.