[LanceW]

I Love the plum look! Early Ruger loading gates are notorious for turning plum. I was told it was not due to bluing methods but rather the silicon in the steel that was used.

Similar thing with the receivers on 1970's Winchester 94. There is a process to make the surface of the receiver more pure iron (passiving?) to refinish those. The castings were "graphitic steel" and they iron plated them from the factory to get them to take blue. Du-Lite has a process to refinish these for the gunsmith.

 

[LanceW]

This is a raw Winchester 94 receiver. I think it is pre 64 It has one thin line down the center of the tang on the bottom. I am thinking this was a cast part.

It looks cast, the post 64 definitely were

From Du-Lite's web page on the Winchester 1894 (Du-Lite is one of the primary supplier of chemicals and equipment for commercial black oxide):

"During the early 1960’s, the Winchester Model 94 was redesigned to accommodate a more economical method of production. The re-engineered receivers were machined from a graphitic steel casting. "

Blackening Post 64 Winchester Receivers