Too funny not to mention:
After 1929, DWM and Mauser were part of the Quandt Group. This industrial group was massive and the Quandt family is still one of the richest in Germany.
I obtained a 345-page thick report from 1969 which lists all the companies that did business with the Quandt group. This includes their own companies and subdeliverers with a turnaround of at least 10,000 DM.
The document came from a library in the GDR... Think about that one
It is property marked of the Deutsches Wirtschaftsinstitut, which was succeeded by the Institut für Internationale Politik und Wirtschaft in 1971.
The IPW property marking is also there. The IPW lasted until the end in 1990.
I selected some interesting companies:
Dynamit Nobel AG supplied IWK with components for ammunition production (blanks, powder and primers).
Dynamit Genschow (Geco) supplied Mauser with ammunition (for test firing).
Albrecht Kind (AKAH) supplied Mauser with weapons accessories.
Winchester in Düsseldorf supplied Mauser with .22lr ammunition, which Mauser sold as their 'KK80' ammunition.