Vlad, These headstamps are generally a product from a German factory in the post-WWI period when the ammo manufacturers in Germany were trying to find some paying customers and turned to the US market by making various 32 and 38 revolver cartridges. Otto Witts book on 38 Special headstamps has page after page of these, most unidentified. Often these are found in boxes that identify no manufacturer. In this case the box label identifies the maker as the International Cartridge Company in Germany and imported by J L Galef in New York, according to Otto. I have the same box that Otto illustrates but with one of the other, slightly different headstamps Otto illustrates. I also have this headstamp in an International box but the importer on the label is Fred Baffer & Co in Chicago. The Eagle Cartridge company and Keenfire have also been identified as manufacturers. Apparently all these were names of convenience and never really existed, or at least there is no record of them, I have been told.
Otto does identify your cartridge by International as probably Selve Kornbiegel Dornheim A.-G. in Smmmerda. This could be true since I have a box with no manufacturer indicated but the cartridges inside are headstamped “SKD 38 S&W. SP’L.” There is a lot of variations on these type of rounds as to where the periods are. The SKD marked rounds are probably later since they have a nickeled primer.
Some of this was covered in a previous thread on the SOS marked ammunition from this period.
A really interesting area that I have seen little research on. What were the companies in Germany and Austria during the 1920s and 30s, and what names did they use and where did they sell their ammunition. A great research subject for someone to write up for a IAA Journal article.