The important thing as to value, if that is the question, is whether the stock matches the rifle and its condition. Can you do images of the stock and how it is marked? Also the right side of the receiver?
Regarding rarity and desirability, as the others have said, BSW (Berlin-Suhler Waffen- und Fahrzeugwerke) is a desirable maker, possibly the most desirable 1937-1939. 1938 is the most common year, both in ranges made and observed rifles that have survived, they are known into the "c" block at least, although there are two "d" blocks known that were assembled by the sister plant at Weimar (bcd). By 1939 the firm was moved away from rifle production, to take up MG34 production, they made about 14k 98k in 1939, making it the lowest "normal" production year for them. (1936 only one rifle is reportedly known, doubtful many were made, if one came up for sale today, in original condition, it would probably break a price record)
The company (BSW) itself is probably most famous for their sporting rifles, bicycles and motorcycle production, but they made the 98k 1936-1939 in small numbers, and they made rifle barrels well into 1942 for JP Sauer. Later they would play a key role in MG34/42 production. The firm has a direct link to Simson Suhl, which also made rifles and commercial products, which BSW continued after Simson was nationalized by the nazi regime in late 1935 (bicycles, motorcycles, automobiles, children's strollers, and many other things- bicycles were a main product of the company through out its history)