This fella - DWM 528. It's what the M1908 is proofed for and what feeds properly through the Schoenauer Magazine:

Here's a thread (from another 'site) where an Anschluss MS was discussed recently. There have been others posted on NitroExpress in the past: Anschluss

This Thread, from yet another 'site, contains information regarding the Schoenauer magazine and the necessity of proper fitting cartridges to ensure its smooth operation, along with several other references. Again, most / all of this info. is also to be found here on NE: AfricaHunting