Gil: from Colonel Charles Askins,
The Shotgunner’s Book, A Modern Encyclopedia, 1958
https://archive.org/details/Shotgunners_Book_The_A_Modern_Encyclopedia/page/n27/mode/2up Present (Winchester Proof Steel) alloys shape up like this:
Carbon .45% - .50%
Manganese .60% - .90%
Chromium .80% - 1.10%
Molybdenum .15% - .25%
Phosphorus .04% maximum
Resulphurise to .04% - .09%
(AISI 4147 with slightly low manganese)
The single sample I had tested, of which unfortunately I don't know the DOM
C .34%
Nickel .09%
Cr .62%
Mo .3%
So non-standard (low Cr and high Mo) AISI 4135 medium carbon low alloy with a low concentration of nickel.
I'm no help with how to blue the stuff, but Mike Hunter would certainly know, and I hope he's still at it.
http://www.mikehunterrestorations.com/
