After spending many hours finely sanding this part to perfection, I am nearing completion. After test firing to see if I am getting a proper amount of hop, I am quite pleased to say that I have seen a boost in range by about 50-100 feet. My upgraded KWA M4 cqb uses a longer 363mm madbull tight bore and gets perfect compression, so it had long range to begin with (over 200 feet) but now i get very long and flat shots. I am also seeing a jump in velocity; before, my gun shot 344fps, only slightly piercing the bottom of a soda can, but now it is shooting completely through the bottom. My groupings are also tighter. For skeptics and others who are doubtful of how this can make such dramatic improvements, I will now state the theories as to why this works so well:
Range: this is the tough one to explain simply, but i'll paraphrase the theory that I have come to believe. On a traditional hop-up, backspin is applied very quickly, since only the bucking's hop mound protrudes into the barrel. This makes the axis of rotation above the bb's geometric center, causing the bb wobble while in flight, effectively increasing air resistance, and slowing the bb more quickly. On the rhop, backspin is applied much more slowly, allowing the axis of rotation to be directly or at least much closer to the bbs geometric center, significantly reducing wobble, and therefore allowing it to pass through the air more easily. Again, a little theoretical, but it does make sense.
Velocity: with the rhop patch being the contact point of the bb, one can choose the bucking that seals the best without worrying about performance. I was able to use my old KWA bucking which sealed air much better than my 2gx bucking, even though the old bucking was long worn out. Since The contact mound must be removed, I could still use my old and better sealing bucking. I gained a lot of fps as a result, but results can vary greatly in terms of fps.
Accuracy: This is obvious. The patch contours to the bb, fundamentally increasing accuracy. The patch is also pre-fitted to give desired hop, so inaccuracies of the actual hopup unit are eliminated as well.
As great of a product this is, I would ONLY recommend this to more skilled airsoft mechanics because everything must be very precise. I used 400 grit sandpaper and a dremel and sanded and ground this to fit perfectly, as anything less will cause flyers, overall loss in accuracy, etc. There are many guides to install this online, so i'll leave that to the customer to figure out. But overall, this WILL make your gun perform like a champ, but only with the patience and craftsmanship to get it right.
Increases range a lot (id say the average gun should gain 75 feet of range, assuming everything will be done properly
Allows the use of the best sealing bucking, so I gained fps in the end (search "aeg floss mod" on youtube for a great way to maximize airseal)
reliability might slightly go down, because the possibility of a pinch jam is greater since the patch is not connected to the bucking. If it does cause problems, just glue the patch to the bucking by following the online instructions mentioned above. I've had no problems with jamming, but i thought it might be good to point that out.
Really, nothing else. Labor, fine tuning, and the need of tools are not cons. they are a part to this product and should be expected. Just be patient with it, and the many hours you could be potentially spending will be worth it. Nothing is more gratifying than watching your bbs fly and fly until you lose track of them when all is said and done.