Notes from Brad Dixon:
This rare cartridge is only shown in a Stiegleder catalogue which is earlier than the well-known catalogue from c1926. Based on the Stiegleder addresses given in catalogues and advertisements, this catalogue could be pre-WW1 but is most likely c1920-1923. The 11.2×62 uses the same “G” Mauser case type (rimless with 12.5mm base) as the 10.75×63 (M57) but has a larger diameter bullet. The shoulder starts from approximately the same position with a similar length neck to the 10.75mm version. Known in two variations with SP and FMJ-HP both with the “R.W.S. NÜRNBERG” headstamp.

These cases do look factory made but this was never listed in RWS catalogues nor does a factory drawing of it exist that I know of, Alternatively, this case could have been produced from 10.75×63 (M57) or even 10.75×68 (M58) cases. Identified as for a “Steigleder” rifle and listed as such in the Steigleder catalogue. In the c1926 catalogue the 11.2mm is shown as the larger 11.72 Schuler cartridge which had obviously gained greater popularity. This is not a rimless version of the 11.2x62R Dreyse (GSP47) as that has the larger Dreyse case which has a raised “MB” type case but with a c13.3mm diameter base. (Dixon Ref. GSP80)

The authenticity of this specimen has not been confirmed yet. It is listed on the website as probably an original specimen, but pending confirmation.