Just came across this
Colonel Charles Askins,
The Shotgunners Book, A Modern Encyclopedia, 1958
https://archive.org/details/Shotgunners_Book_The_A_Modern_Encyclopedia/page/n27/mode/2up The Yankees who made sportsmen nickel steel-conscious, with typical reticence, never revealed the contents of their alloy; but it was generally
Carbon .35% - .45%
Manganese .50% - .80%
Phosphorus maximum not over .04%
Sulfphur about the same
Nickel from about 3.1% to 3.75%.
Our specimen
Carbon .39%
Nickel 3.17%
Manganese .65%