I found these two specimens at the 2015 ECRA meeting in Germany. There was also a discussion regarding this cartridge on the IAA Forum not long ago. According to Brad Dixon, this extremely rare cartridge is not shown in any known RWS catalog but two undated RWS factory drawings exist, both showing identical dimensions and numbered M244 & M245. The “M244” appears to be a mistake as M244 was already allocated to the 8x42R M88 (M4). Examples of this case do exist with “R.W.S.  N” and “N  8x57J” hs. These are likely to be factory produced from 8×57 case but appears never to have advanced past the experimental  phase. This may well have been an RWS  factory experiment to produce a ‘middle length’ rimless M88 cartridge similar to the DWM 8×51 Mauser (M8). The headstamp would imply likely production prior to WW1 c1910 but possibly as late as 1920. Factory drawing M245a is dated 1923 so this is most likely to have been before that date.

According to Peter Petrusic (via Peter Skala- RSACCA #195) this is a 8×49 Pre-WW.II German assault rifle experimental which was part of the 7.9×33 Kurz development but considering the factory drawing this is unlikely. The shoulder position appears the same distance from the base as the 8x51Mauser (M8) and it may well be that this would fit in weapons chambered for the 8×51. Specimens known with “R.W.S.  N” have an unusual tinned jacketed bullet with flat top and a slightly stepped bullet (down to 7.8mm)