Wonder if it was a patent model. For a time you had to submit a working model to get a patent. I don't know how to search patents efficiently, so I have no idea of where to start.
I am sure it would fire a round. Trying to turn that barrel after the round is fired would be interesting. You would just be using your fingers. And then, you would have to bring a rod to drop down the barrel to eject the case. But for one round, it would work.