AHaa.....I have an enrgaved '51 Marshall from Pietta, but the screwheads aren't cut and engraved or blued. I notice that because I cut, blued, and engraved my scewheads on my version of a flintlock Masonic rifle that I dabbled in engaving some components.
What graver do you use??
p.s.
Now I remember that I cut those screwheads with a small file, and then heat-treated them to a nice blue color. It's been a while since I did it.