This was a standard location for inspection/acceptance for all makers until approximately 1939 when it began to be eliminated for expediency. The phase out was gradual depending on the producer, some early, some later. Mundlos continued the stamping at that location until the end of their production in late 1944. Other WaA were eliminated over time as well such as the top of the flashguard, second stamping at the top of the pommel and some internal acceptance stamps.
Sure enough Andy WAa 253 , I am impressed by you and Slash , you two really know the bayonet game , great having someone that knows so much about the bayonets that we enjoy collecting .. Some may say , bayonets don't do anything , they just sit there , but I frequently go over them , pull each one out , oogle it , look them over , oil it and put them away , When I'm gone the are my son 's bayonets , So I maintain them , anyway thank you very much