The receiver is definetly a military Mauser Standard Model.
The markings on the left receiver sidewall found on this specimen is not uncommon.
The Standard Models showed from the beginning of their life the commercial proofmarks.
The bolt looks for me as a typical unaltered commercial bolt(pear shaped bolt knob, long striker nut and the root of the bolt handle).
The bottom metal often to be seen on Ferlach (and sometimes Suhl) made Mausers. Never an Oberndorf made feature in that configuration.
Summing it up: A mixture of different parts.
