[lugerholsterrepair]

Whoever had removed the rust, had scrubbed it with steel wool which spoiled and degraded the surrounding areas of otherwise perfectly good blue.

Yes..exactly what steel wool will do without oil. If used with oil 0000 steel wool is perfectly safe for light surface cleaning. I have even used a courser steel wool & OIL on pretty heavily encrusted areas with no damage to bluing.

I have never liked the brass wool as it tends to impregnate the surface with brass leaving a gold sheen on the pistol.

If I recall, the dearly missed Tom Armstrong suggested soaking rusted parts in a good penatrating oil until the rust is saturated, then scrub away the rust with new burlap.

I once had a Luger so rusted I had to hammer it apart with a ball peen and wooden dowell. I soaked it in Kroil for 2 weeks and it didn't touch the rust. I chose to chuck up a wire wheel in my bubba lathe/drill and whisked away the rust in no time and the Luger is now completely in brite white steel.