I pride myself on being able to spot a refinish. Yet, none of the usual clues to a refinish are present on this gun. However, the finish texture is too coarse for a gun in this serial number range. That suggests a refinish, but the markings (except for the serial number) still show displaced metal that normally is removed in a refinish.
I suspect a Turnbull-quality restoration. However, Turnbull knows the proper texture of finish for a gun in this serial number range and would not have applied such a coarse finish. He also would not have used a later hammer, unless that was on the gun when it came to him and a proper hammer could not be located. I am told that Turnbull has dies to duplicate original markings, so that might explain the crisp markings, but I still cannot imagine that Turnbull would have applied such a coarse finish.
A totally unsubstantiated and speculative explanation might be that the frame was serial-numbered and then not finished and completed until far out of serial number sequence, which would explain the later finish and hammer. That also does not explain the odd appearance of the serial number.
I will be most interested to learn the opinion of the appraiser.