Although I would be inclined to use Jerry's idea, John's suggestion is more sensible.
In my state, a newly registered handgun must have provenance...It has to have come from somewhere...Even if you made up a number and stamped it, there is no way to know if that number is already registered...maybe as stolen, maybe legitimately...
The idea of breaking it down & selling the parts is the best. You can make as much doing that as another legal Luger would cost. The frame, since it is not useful as is, could be sold to someone wanting to make a 'baby' Luger, or a carbine, or some such where they did not want to cut up their own frame. There are always people here wanting to restore a ground-down grip lug.
Whatever you do, good luck.
