I've never measured them, and cannot do so now, but my recollection is that the '03 barrel is considerably thicker at the chamber end (which is why they CAN be set back and rethreaded) and, then, has a sharper transition to the ultimate straight taper. Krag barrels are quite slender, with a noticeable step at receiver joint.

I'm not sure that the spring clips on the handguard would hold properly - in fact, I'd guess they would not.

You'll need someone who can give you micrometer readings!