Vaderman — the NERF rifle has a lot of differences from the real prop, but there’s also a lot of attention to detail that I think make it a great base for an affordable costume prop. I picked mine up from Amazon for $55 and most of the decent replicas I’ve see are over $1000. I can’t imagine what Adam spent on his between all the various materials (and the fabrication tools needed).
I think the barrel, stock and tuning fork are all short. For now, I’m giving up on replacing the stock as it would require a lot of custom 3D modeling to have it integrate cleanly (even if you don’t care if the gun fires anymore). I think you could probably extend the barrel itself between the box section where the darts are loaded and the scope. Probably relatively easy to achieve with some PVC pipe.
After a bunch of tests, the attached photos are where I got to with the new tuning fork. I think this gives it enough additional length for me and the improved accuracy of the design makes it feel a lot more like the real prop. I had to mess around with the barrel diameter a bit to make it still wide enough for the darts to pass through. I’d say it shoots properly about 50% of the time, but the darts do sometimes hit the inside of the narrower tuning fork barrel or the fork itself. But, I’m satisfied for now.