My guess is that the "serial number" quoted on this gun is actually the smaller working number ahead of the barrel flats. I own an E.C. Schmidt gun similar to this one and it is devoid of a "normal" serial number - i.e., a number behind the trigger guard or otherwise externally visible.

Based on that, I would put this gun in the circa-1903/4 range. The mechanics of the gun - shape of the action, steel barrels, sideclips, etc. - would all correspond to a date in that area.

Best,
Ken