I don't know a lot about this shako. Life has kept me a little separated from the hobby recently, but I am always hungry to hear ideas.
It is a Bing. I bought another Bing helmet to put the liner in, but I don't know if I should. Not sure why someone took the liner out over the course of its 100 year history, but im happy to have the piece regardless. The wappen is put on by split pins.
Here are some photos. Happy to take more detailed photos with my better camera if someone wants them for a study.
Gabe