What about the detachable shoulder stocks that were all the rage in 1910? Lugers, Mausers, even a few Colts had them. My C96 had one, though frankly I was less than impressed because the attachment wasn't rigid enough. But one source stated that in the Winter War, some users thought that handguns with a shoulder stock like that were almost as good as a submachine gun. But as far as the grip on those guns, it puts the other hand too near the wrong end of the gun and it is a shooting position unlike no other.