Marksc - Could you post a clear, up close, picture of your front-sight attachment and muzzle crown?

(This is always a valuable clue on carbine barrels).

Attached is a picture of two Stokes Kirk catalog pages. Some "carbines" have been made privately, outside Springfield Armory, (in the early 1900s and since), from surplus parts.

A carbine stock with no cartouche or 'circle P' stamp was likely put on outside of Springfield Armory.

---