Your Krag's original front-sight has been replaced with a 1903 Springfield sight. This is not Springfield Armory work.

The barrel has likely been shortened and the muzzle 'stepped-down' to accept a Krag or 1903 Springfield bayonet. (Both should fit).

If your barrel is around 24 inches long, it was likely done by a VFW or American Legion Post for their Honor Guard.

If a 22 inch barrel, the work was possibly done by Bannerman's or Stokes-Kirk surplus stores to make a cheap imitation "School Rifle".

Not a lot of collector interest and value is lowered to around $300, but, it still can be a fun rifle to shoot!