1903 (A-what?)

[RDG]

Here are two photos showing the "extra" vent hole on the right side of the receiver, one with and one without a flashlight shone into the receiver showing it is drilled all the way through. If this is an extra vent, where might the first one be? From previous discussion, does it appear this may be a Marine rifle? I like the comment that it may have been reproofed; to what pressure one wonders? You would think there would be documentation of this work. Anyway, I think it's a fun shooter and have no qualms about using ammo my gunsmith uncle loaded back in the fifties as well as some I have reloaded (nothing HOT) in the last decade or two.