This unknown headstamp is found in two different 7,65 x 54 mm Argentine Mauser M. 91 nickeled dummies, one with three knurled cannelures and another including six flutes (as the one in the picture). The first is a typical DM-K dummy (367E1) that can be found with cases dated between 1891 and 1894 and the other is an Argentine model made with cases dated between 1892 and 1897.
Same headstamp was also found on an unidentified 7,65 x 51 Rimmed dummy cartridge with nickeled case and three knurled cannelures. Rim and head diameter match those of the 6.5 x 54 R Beaumont-Mauser case number 392B and it may be DWM case no. 369 from 1891 (M./91 Kal. 7,65 mm Beaumont). It looks like a typical DM-K dummy.
Can anybody provide information about this headstamp? Any other examples?