As long as we're taking shots in the dark...
It appears to be a military stock from a Mauser, but not a 98. Looks a whole lot like the stock that came off my 7 x 57 model 93 or model 95 Mauser. Spanish maybe. The stock went almost all the way to the end of the barrel. short rifle or carbine with a turned down military bolt handle.
Could also be from a Swedish Mauser , they were stocked all the way to the muzzle.
That stamp on the stock should tell the tale .
That skinny magazine box now has me leaning to the Argentine Mauser , non staggered box protruded out the bottom.
Gary