OK, so there was at least one Mannlicher-Schoenauer marked Modell 1906, chambered for the obscure and short-lived 6.8x57 Chinese cartridge. This was apparently a short run of military test rifles. But the Chinese adopted the Mauser 1907 instead. As the DWM case number 511A shows, it was the 7x57, case # 511, necked down slightly to take a .276" 139gr bullet. Any advantage of this cartridge over the established 7x57 would be imaginary only. No commercial sporters, neither Mannlicher-Schoenauer nor Mauser, are known. Alas, even the Chinese soon rebarreled their M1907 Mauser rifles to 8x57.