This is MB105 from Dixon. This case type was listed by both RWS/Utendoerffer and Egestorff. It is not to be confused with the 9.2x51R (Roth #192) (A22 : which uses the larger 11.15x58R Werndl case type) or the straight cased 9.5x51R Express (EXP37). This was given the “MBb/a” designation in RWS/Utendoerffer c1884 and c1900 catalogs and generally this implies a modification of the original type (ie a modified ‘b’ type in this instance)