Ok so this is something cool. I had a simple crossbow put together for a while, and it functioned perfectly.
Then I decided to pimp it out a little. Instead of using the track on the bottom half of the stock to fire directly, it now holds a firing pin. The front of the gun is loosely based off of the TR-8, with the turret directly borrowed.
The turret system works wonderfully smoothly, and while the lock looks ugly and just stuck on as an afterthought, it holds the ammo perfectly in place, arguably better than that of the TR-8. With a little effort, a 18-shot turret could probably be added for extra aesthetic and functional overkill.
I have attached enough photos, I hope, for anyone to build this, but if you have a query feel free to ask :)
And if anyone has any ideas as to what I should try building next, drop me a comment ;)