Colts like the Detective Special in the previous post are a bit trickier than a S&W of the same vintage, since they have the full serial number stamped in only one place, in this case the crane/yoke cut-out. If that is gone, the serial is lost.

For the same reason, a lot of the old DA Army Colts which had the five- or six-digit serial only on the butt lost theirs when they were upgraded with the 1901 lanyard swivel at various ordnance depots, and were then just re-stamped with the assembly number which was the last four digits of the serial and all that was available from elsewhere on the gun. Some Colt collectors are still fretting about the legality of those.

If someone were stuck with a S&W like this one, as long as one can establish the correct serial conclusively from matching numbers in two or more other locations, one could always just re-stamp it on the butt and touch up the finish, and no one would be any wiser. That’s just hypothetical musing, not a recommendation or legal advice, of course