JohnE:  Your bolt handle (flat checkered knob) appears to be for the Model-1912 Karabin.  The front sight looks like a Lyman 'banded-ramp' (covering up the location of the original military sight).

  The stock appears to be a cut-down M-12.  I can see a plug where the rear swivel/'eye' screw use to go through the butt stock.  The military butt plate has been replaced. 

It looks like the small cross-hole that normally goes through the front of a rifle style trigger-guard is filled.  This would suggest it may have had the 'eye'-bolt arrangement, I described above, and this was cut off to streamline the guard.

  I don't see any mysteries here.  It is a 'sporterized' Model 1912.

(Photos of Norwegian M-1912 butt 'eye'/swivel).

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