For more concise info about the R-hop and its installation, please go to this link: http://forums.airsof...hp?topic=4820.0
I've been working on and answering questions about the R-hop and decided to cobble together some of the responses into an installation manual of sorts which covers the basics. The thing I want to emphasize is that with increased contact area comes increased sensitivity to downward pressure from the bucking. As a result it takes a different feel to get one of these adjusted right, but once it is installed correctly it should require little or no pressure from the hop arm above, and the hop dial should be used for fine tuning only lest you deform the hop from its bb hugging shape.
YOU DON'T NEED TO FOLLOW MY INSTRUCTIONS, THEY ARE JUST A SUGGESTION AND AN EXAMPLE OF WHAT I USUALLY DO. There is also an FAQ down below which is a great quick reference.Feel free to experiment.
every hop window is different, so I can't sell patches which are drop-in ready. I ship all of them over-size for people to cut down.
The process is best done with a VERY sharp knife and/or sandpaper, in some cases wrapped around a dowel, and a small round file. This sandpaper must be a fine grit, usually about 400, and when you're finished clean the patch thoroughly to avoid getting the grit in your barrel. You'll definitely need to cut down the two sides of the U and depending on your hop window and ammo you'll need to cut the channel deeper as well. I find its best to cut the piece to length LAST because thats the easiest cut and for whatever reason edges are always more difficult spots.
When you have one you are ready to drop in and test, cut the hop mound off your bucking, drop the patch in the hop window, and slide the bucking over just like a regular G-hop. Then, and this is the CRITICAL step, insert the whole thing into your hop unit and TEST IT MANUALLY FIRST. Put a bb in the chamber and push it through with a small rod, old hex key, or anything small enough. This is important because when working with a hop unit like this its super easy to apply too much force and make it impossible for your bb to pass. The bb should pass with just a gentle touch. If its producing mild resistance it probably won't jam, but you'll probably have wild over-hop. This really is an important step because, as always when messing with hop units, if you over-clock it you'll cost yourself a piston.
One thing I will say is that once you get the mod running the way you want you will be able to improve reliability by permanently adhering the contact patch to the bucking. Don't do this until you get the backspin you want, otherwise it'll be a mess, but put the contact patch in, and slide it all the way to the back (gearbox end) of the window. It may help to adhere it here with a MINUSCULE touch of CA at the four corners to keep it in place, but don't let it get anywhere near the inside of your barrel just drop it on the outside and let it wick itself as far in as it'll go. (in theory you can use tape too, but that messes with thickness and airseal blah blah blah. Then take your hop bucking and turn all of it inside out except the lips. Put a drop of CA on top of the contact patch and unroll the bucking onto it over the barrel. If you do it right it'll permanently attach the contact patch to the bucking and keep it from being drawn forward into the chamber which causes a pinch jam. (obviously) This is something I do to mine, but only when I finish experimenting because it somewhat permanently attaches everything. Getting a bucking which has been attached like this off it a bit of a pain.
If this still leaves you dumbfounded there is a great deal of information in the G-hop thread. It is an excellent resource. Please read that first:
Here are some images, some of which were stolen from other threads, showing what a correct install looks like. Any further images people would like me to capture pertaining to user installation of the contact patch I will try to capture and will add here.
I also developed a new technique. You see the problem is that you can't really see how the contact patch is sitting until you install it into the hop unit fully. At the same time you can't really see how its sitting when its in there because the hop rubber obscures it. If you're really desperate to see how your contact patch is sitting, and where the interference is, you can cut the lips off a hop rubber, while retaining that edge which is required for the barrel to seat properly, and then install it in the hop unit. This allows an unobstructed view of the inside of the barrel and the contact patch.
We already have seen the demonstration that the R-hop is somehow able to magically propel a bb further than a bb out of a normal hop despite no differences in spin velocity or muzzle velocity. Here is a theory as to why, which I've dubbed the "vibration theory."
[quoteMy R-hop does not produce the oval shaped, or vertical skew, that a "flat hop" or regular hop with SCS would do. Shredder himself recommended that a mod akin to what people now called the flat hop (flat hop is just the latest name for a mod which is 5-8 years old, and I find it a bit amusing watching everyone here reinvent the wheel for the hundredth time) where you remove the hop mound and rotate the bucking to work in conjunction with the SCS nub in order to better produce the bb contour. The problem with that system is that there is on give. There is almost no rubber anywhere in there and its all being held in rigid plastic. Also, given that the SCS is round, the length of contact is extremely short. Your spin is therefore on axis but inconsistent in velocity so you get that vertical skew. The R-hop can use a wide variety of different nubs to press down, including the SCS, mainly because very minimal downward pressure is applied when installed properly. I do recommend a soft and long nub like a firefly rather than a short and hard one like an SCS. Honestly with an R-hop you'd be better off with a regular soft round nub than an SCS. What makes the R-hop special is that its already contoured to the shape of the bb, it protrudes as far around the barrel as possible, and is as long as the barrel window will allow. As a result spin is applied much more slowly. You see normally, with all these systems except the flat hop, the length of the contact patch is extremely short. so the downward force must be very high and the spin must be applied to the bb very rapidly. What makes the "Flat hop" which evolved into the G-hop, which applied into the HE G-hop, which evolved into the R-hop which evolved into the ER-hop (each being superior to its predecessor) is that the contact with the bb is much longer than on the hop mound (lump in a normal hop bucking). This longer slower acceleration allows spin to be applied much more gently and stably to the bb producing more stable spin...... and this is where we enter into the realm of theory. Lets start with the top theory. The top theory is that if you were to spin a top (we're talking about the child's gyroscopic toy here) the more stably the spin is applied the more smoothly the top will spin. The G-hop, R-hop, etc are like slowly but firmly spinning the top between your two fingers. If you do this the top will spin smoothly and on axis. Spin imparted by the hop mound can be likened to spin applied to the top by flicking its rim with your finger. The result will almost always be spin which is off the top's central axis and so it will appear to wobble and its spin velocity will be much less consistent. Reports from the field support this. People who've used my R-hop, even under severe over-hop conditions, report that the bbs will fly skyward but will all come down to land in the same spot. Similarly groupings are very tight because your spin will be consistent and on-axis when you have it tuned properly. Now though we have to delve into the realm of even crazier theory to explain an observed phenomenon: extended range. You see with the G-hop and now the R-hop we have a great deal of evidence showing that not only does this system make your rifle more accurate, but actually extends the distance the bbs will travel and their flight pattern. This is puzzling because, superficially, this seems impossible. I myself refused to accept it for the longest time because I couldn't come up with an explanation for it. Here is my theory though: when the bb passes the mound to have spin imparted its actually not rotating around its center, its being forced to rotate around an axis above its center. This would cause a tendency to reorient a bb to bring its center of mass, which doesn't exist at its geometric center, in line with its center of rotation. While this may not fully be possible it will create a tendency for the bb to find an axis of rotation which coincides with a center of mass as far from the geometric center as possible. This will create a "vibration" or "wobble" in air which will increase its presented surface area to the air when flying that should increase drag and decrease range as well as reducing accuracy of course. Contrary to this a longer and slower system of imparting spin like the R or G-hop attempts to force the bb to rotate around its geometric center giving it the tendency to find an axis of rotation which as best as possible causes the geometric center to its center of mass or rotational center. This reduces this wobble or vibration in air allowing reduced drag and increased flight distance. In theory it will also allow for the longer flatter trajectories we've witnessed.
THIS is the best theory I have as to why the R-hop actually, without adding any more velocity either forward or rotational, increased the distance a bb will fly by a significant margin.
This thread will also be periodically edited by ASF staff to try and keep all info concise and keep all irrelative/extraneous post from cluttering it up.
Edited by airborne101, 25 February 2013 - 12:15 AM.