I've just checked Robert Ball's Mauser Military Rifles of the World (Mauser bible?) and your rifle has been modified a bit. The bolt handle has been swept back and stock (and barrel?) shortened. The rear barrel band is off another rifle.
Also the original stock didn't have finger grooves and the rear sling had a quick release.
Not so original but still looks like a handy fun rifle.
Edit: The barrel doesn't look to be the original - the step is way too close to the muzzle end and would be closer to the end of the original stock.
ParallaxBill forum used to have more knowledgeable people on all things Mauser but it's almost dead now. You might want to ask questions there but it might be a long time for a reply.