Mike:  Welcome to the KCA Forum.  It is not likely anyone will know exactly by whom or when your Krag was modified, but, it was not done by Springfield or the U.S. government.  It would be interesting to know if it will accept a Krag or 1903 Springfield bayonet in its current configuration.  It is possible a VFW Post had it altered locally to appear more like a 1903 Springfield.  It looks like you have some nice parts and an altered Krag that can still be a fun shooter.