That is a 32-20 Hand Ejector, 3rd Change that would have shipped around 1915. The finish looks too good to be true, so my guess is that it is likely refinished at some point in its life, but more detailed examination would be needed to be certain one way or the other. The good thing about the Wonder sight is that it is probably more accurate than the slot in the top of the frame, but I am not sure if the top sideplate screw hole is modified or if the sight just screws into the existing hole. If the later, it is easy to remove if desired.

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Gary
SWCA 2515