1898 carbine #105621 (1898 rifle for comparison), I can't see any evidence of any original holes or filled in holes. These 2 holes are properly spaced apart so I can mount any of my Krag rear sights OK and the holes 'appear' (don't know for sure) to be tapped original M4x1mm because all the sight screws work OK too. So I can install a rear sight but obviously not a hand-guard. Both holes are shifted ~0.75" toward receiver. This piece has a 22" barrel with what appears to be correct front sight (not pictured).

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