The strange coloured bluing (light and dark plum, bronze, and red) is a characteristic of the refurbs and probably all or some original output ftom Megnogorsk from '42 on (red). Judging from the pitting on some, some sort of rust protection was necessary and I leave my refurbs as they are. One with a deep plum bolt/carrier shows no wear on the finish after several hundred rounds so I think the re-furb factories knew what they were doing. Making them white in no way makes them correct as a true non-refurb would have a neatly stamped serial on both parts. The strange colour is supposedly due to the composition of the steel in bolt/ carrier/ bolt support insert. It would be interesting to see if cold-blue on a bare one makes a strange colour.
milsurpo