Part of the problem is that no one knows how good or bad an idea it may be or what to make of it altogether, because nobody has ever seen anything like it. On the other hand, your other thread, which is full of similarly innovative constructions of yours, is one of the most active threads on the entire site. But I would say the majority who have dealt with the VSR's stock 45 degree sear system or the small, sears and thin trigger boxes of other guns have at nothing else questioned the long term reliability of that. Or their piston end. Or worried about breaking their bolt handle. Or blasting off their cylinder head. And of course everyone is concerned with accuracy stuff like hop-up chambers in the gun like everyone is familiar with. Innovations that make things stronger, or more effective in an easy to see or understand way. But this is an abstract concept to everyone.
This is the first time I'm seeing this. It is also a new concept to me. I will try to help, but obviously this will all be mere speculation.
Well, I take that back, this first thing isn't speculation. The conventional hop-up bucking does more than make the bb spin. It allows for the nozzle on the cylinder to seal properly with the barrel. You will need to find some way to produce a seal between the bucking and barrel, for instance by using a bucking with no internal mound and a barrel with no window in the rear, and an anti-blow-by ring to ensure that the bucking doesn't simply expand from the pressure. Nothing to provide hop obviously.
But from here on it's speculation. In a conventional barrel system, the bb hits the bucking (on in this case, o-ring), it is pushed down, and then subsequently shot upward. The bb bounces a little and is eventually stabilizes... somehow (the exact means being debated in that other thread). But regardless of how it occurs, the bb has no chance of becoming stabilized within a barrel before its final exit vector is determined. The exit vector will only be determined by the hop-up chamber. The barrel will only serve to give the bb space to accelerate. The way I see it, it is little different than the bb coming straight off a hop-up chamber in a conventional setup. The only difference is, the bb's velocity, since it has already accelerated, will be as high as it should be from whatever barrel length you use when it hits the chamber. That means that the bb will still travel far, assuming it picks up a good spin from the chamber. But as in an incredibly short barrel, the bb will not get a chance to stabilize at all after leaving the hop-up. To that end I suspect accuracy will suffer. Again, this is all speculation.
The other thing about this setup is the use of an o-ring for the contact surface for the bb. I have not seen this done before either, so it is also speculation. But I do know that most o-rings are considerably harder than most buckings. And hard buckings tend to in my experience be less effective in producing a stable, consistent spin, particularly with heavy ammo. The other thing is that hop-up units with greater contact surface such as the G-hop have shown themselves to be more effective in producing a stable consistent spin than those with smaller contact surfaces. I have not tested this myself, but it is on my to-do list, and I have seen plenty of documented testing on AirsoftMechanics to show it. I don't really understand why it works. I will thus speculate, that due to the harder material, and small contact surface, that an o-ring would not be especially effective in producing the stable, consistent hop. However this is just a guess. I also have no idea how it would behave in this case, because the bb is hitting the hop-up at it's full velocity if it's at the end of the barrel rather than it's relatively small velocity at the very beginning, which may completely change what is most effective for all I know.
So there's my "speculation", not sure if it was much help, but that's all I've got at the moment.
