In nearly 40 years...

[Murray]

Thought I'd seen it all. Even a nice Merkel in-the-white with no markings that was described to me as a lunch box model. 
Has anyone else seen one of these? He wants the slot cut and hole drilled and tapped for screw.
Going to have to ask him if it's been heat treated, I reckon.

[running-man]

What is it off of Ben, a K98?  I wonder what its history is! 

[Phosphorus32]

Definitely a Mauser 98 action if that bolt belongs to it. Lunch box model sounds like a story the guy was told at the gun show. More likely it was acid washed or worn. The finishing is rough, or it was scrubbed. Scrubbing would point me to a Spanish origin. Perhaps a receiver and bolt stripped from an M43, which were mostly recycled German Gew98s. Hard to tell it's origins if all of the markings are gone.