Matte finish on a Big Bore |Winchester Rifles|Forum|Winchester Collector

Has anybody run across a dark matte finish on a new (1982 in this case) that wiped off with acetone and had a nice Winchester blue under it?  I bought an unfired .375 Big Bore that had a dull matte finish only on the receiver. While I was cleaning it, I wiped the receiver with acetone and my cleaning rag came out black – the matte finish dissolved – leaving me with a nice bright blue color.  I’ve never seen anything like it on any Winchester. (Production protection? )