Take it to a gunsmith.
No published sn data
Unfortunately, there was more than one company that used the Essex name, The "Krupp" marking was the German steel firm that produced the fluid Steel (Fluss Stahl) used to build the rifle.
No sn data available.
No way to answer without a DETAILED description of ALL markings.
Need the name of the maker to answer. ********* Fluss Stahl is Fluid Steel, produced by Krupp, in Essen Germany. But we still need the make of the gun to answer your question.
I do not know but will know in a month I put it in a wwII gun auction.
The German word for river is Fluss. Fluss is male, therefore it has the article der. Der Fluss.
Brno is in Czechoslovakia, Essen is a city in Germany. Two different countries. "fluss stahl" refers to "fluid steel" made by KRUPP Industries located in Essen, Germany. Since Krupp was one of the premier manufacturers of high quality steel products in Germany prior to (as well as after) WW2, there is a good chance that Brno used KRUPP steel to produce rifle barrels. Especially in the late 1930s.
Fluss - 2012 is rated/received certificates of: Sweden:7
steel = Stahl
The cast of Am Fluss - 2012 includes: Marten Krebs as Nick