Was just looking at some Oxwall cutters and what you said makes sense since the ones I was looking at were stamped British Zone and these don't so these would be after 1949 then.
Just a random history lesson -
After WWII, the United States, Great Britain, France, and USSR divided Germany into "Allied-Occupied" zones. From 1945 to 1949, the US and Britain shared zones and under their administration, restarted essential government services (like the postal system - of which I am a student) and industry. Industrial goods under this administration were labeled "British Zone". I believe this was done to avoid concerns over embargos of goods made by Nazi Germany (labeled "Deutches Reich") or by Soviet controlled zones. In 1949, the 3 allies (France, Great Britain, and USA) created the Federal Republic of Germany (AKA: FRD or West Germany) and goods were labeled accordingly.
Eras of Oxwall tools can be identified by the aforementioned markings.
Brian