You don't see that 'Eagle Stamp' very often on Krags and I don't believe its significance is exactly known.

(It or a variation is found often on Model 1917 rifles, both wood and receiver. It is considered an inspection & proof stamp).

Your rifle was likely - inspected and repaired as needed - sometime between 1904 and 1917, (maybe multiple times).

Krags were in use by some regular troops until around 1907-08. The national guard used them until around 1913-14.

During WW1, Krags were widely used as training rifles.

The US Navy had Krags on some ships maybe into WW2.

Krags were seeing some VFW use into the 1960's.