I have never made a Krag hand-guard from something else.

The 'barrel-clips' are the big challenge and Parashooter did a wonderful job of making a hand-guard from a walnut chair-leg and packing steel-bands, IIRC.

I believe Schwartz, aka Antique Guns LLC, retired due to health problems. He was the source of reproduction hand-guards for vendors like S&S Firearms.

I don't think 1903 & 1903A3 Springfield hand-guards will work as 'donor' parts.