The Chet Shoults Ketland was advertised over 50 years ago as being 8620 after the discovery that all but the springs were that material.
I used only the externals and I think the frizzen spring was 6150 but not sure. case hardened the frizzens and they seemed to work well
and none were returned with premature wear.For over 50 years I have used 1144 for tumblers and 0-1 flat ground for sears and flies.
Bridles were 1018 sometimes case hardened.Screws were 12L14, a leaded steel sold as screw material.
Bob Roller
