JohnE:  Are there any numbers on your Krag's trigger guard and do they match the rest of your Krag's numbers?

  (BTW - Trigger guards can be switched between different Norwegian Krag models).  The large hole at the front of the usual M-1912 trigger guard is to secure the large 'snap-hook' found on the Karabin sling.  This hook can also be secured on the 'ring/stud' that serves as the Stock Butt swivel.

  I have seen pictures of M-1912 carbines with a normal rifle style guard with a 'eye-bolt' type of stud on the left.   This 'eye' was mounted side-ways, through the small hole at the front of the guard.

What style bolt handle does your Krag have?  (Both flat and round knobs seem to have been used).

As I see it, there are three significant facts:  1.  Your Receiver is dated 1913.  2.  Serial # 821 is in the block of numbers (1 - 1,170) used for Model 1912 Karabins in 1913.  3.  The flat area on the top of your barrel is for the military sight base.  Only, the Model 1912 Karabin series of rifles has the rear sight that far back.

More pictures of your Krag showing details (stock, front sight, trigger-guard, bolt handle) will get better answers and stop the guess work.  The "6.5:55" barrel marking is not Norwegian military.  IMHO

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