It could be a Turkish Mauser. Turkey was importing their Mausers up until the end of 1939. After that, they started making/assembling their own (K.Kale) since they did not want to get caught between Hitler and Stalin. They remained neutral until the end of the war when they joined the allies. I have a 1942 K.Kale Mauser.
BEAUTIFUL rifle BTW. Mine looks like it's seen a lot of use.
http://www.turkmauser.com/1938/