No way to answer without a DETAILED description of ALL markings.
Take it to a gunsmith.
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.
No published sn data
No sn data available.
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.
Probably between $800-$2000 depending on condition and the grade of the gun.
You have a rifle made of fluid steel from the Krupp steelmaker at Essen Germany. That is as much information as we can give you from the information you gave us. A gunsmith should be able to identify your gun in person, but we would need a lot more information to make a good guess- sorry.
No published history
http://www.novelguide.com/a/discover/ewb_09/ewb_09_03638.html There is alot of history on the Krupp family on this site. Hope ya find what ya are looking for. Widow Krupp acquired a foundry near Essen called "good hope", but later sold it.
Krupp Essen is a large German company engaged in many engineering fields.
Krupp is a German steel company. they made military guns during the wars Germany had. I believe krupp also made shotguns, but not sure