Regarding the M stamp; from the Ruana book, "Hear The Hammer", on page 96, "From 1938 to 1962, Ruana knives were made from Studebaker car springs. In 1962, a high carbon steel became available that was the thickness and weight needed for knife making. When Ruana changed to high carbon steel, the stamp changed from a knife to the M stamp". The M stamp was used from 1962-1983, then R.H. Ruana, but no M stamp from 1983-1984.

Pap