This cartridge is the rimless version of the 6.5x27R (T41). This was apparently only produced in a small quantity by RWS/Utendoerffer. It was shown in RWS catalogs from their c1900 to 1912 catalogs but production had ceased by the 1921 catalog. It was shown in an RWS factory drawing of 23/01/1924 although production had clearly finished by then. This was one of the few rimless cartridges in the c1900 RWS/Utendoerffer catalog. It was originally used in light single shot and combination rifles and according to Erlmeier & Brandt  it was later also used in Target Pistols. The Erlmeier Brandt reference is 33B (Vol. 3)