I know nothing about this gun except for what I have written about it for dnd. I am sure in its IRL form, it is highly improbable that it is operational but you'd be surprised.
I am not a gunsmith or an engineer but for hypothetical purposes you could possibly make it look like that and still fire a single round.
I mean maybe, there probably should be a consequence for forcing time travel on another. That's a very specific condition and I feel you have a sound reason behind the question and I'd love to hear more