Carcano,
I do not have the RWS "Schoenzeitladung" either but do have some ca.1940 DWM versions of similar loads (not the cartridges, but the data). All the 6.5mm cartridges are loaded the same. The 6.5x52R is not listed but the ballistically similar 6.5x58R is. The 6.5x58R is shown as being loaded with 3.3-gram bullet with 0.85 grams of Tr.target P. 1912 powder for a V25 of 648 m/s and E25 of 70kgm, from a 60cm barrel. It is interesting to note that the other 6.5mm cartridges used 1,00 to 1,05 grams of the same powder to produce the same velocity with the same bullet. DWM also had "Schoenzeitladung" for 7mm and 8mm cartridges, which they called "Cartridges for use during the closed season".
Until the 1939 proof law, the bore (not groove or bullet) diameter (pre-1912) or bore diameter and case length (post 1912) did not represent the nominal cartridge but represented actual dimensions (within tolerances) of bore diameter and case length only. Case diameter, shape, or presence of a rim are not represented. Consequently, any set of proof marks may be found on rifles chambered for different nominal calibers. one example of this would be 7,8/57 which could be found on rifles chambered for 8x57I, 8x57IR, 8x57R/360, or 8.25x57R Hagen nominal cartridges. After implementation of the 1939 proof law, it was required that the name the cartridge was normally called by was marked in a visible place on the rifle. This helped clear up the prior confusion.
Mike