Have a Model 1899 Carbine that some previous owner has mutilated with two holes in the left side of the receiver. The holes are approximately 1/8" in diameter, approx. 3/8" apart (center to center), and are tapped.  Currently there are blanking screws in the holes.  To give an idea of their location, they wipe out the "EL" in SPRINGFIELD, and the "AR" in ARMORY. 

Can anyone give me an idea of what these holes might have been for?  All I can think of is some sort of scope mount.  (It seems like a weird place for a receiver sight, but I suppose you could put one there...)