Harry: a nice example of DelGrego cyanide colors
Bone charcoal recase. Note 'ghosting' around some of the pins
It is possible to recolor actions using cold blue and an acetylene torch, and the results are...uh...not attractive
Krieghoff bone charcoal case coloring, again with 'ghosting'
Krieghoff cyanide colors; used primarily now related to difficulty case coloring the chrome moly (and maybe other stuff which they are not sharing) alloy frames
More on cyanide coloring
https://www.doublegunshop.com/forums...55072&page=all