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R-Hop™ Installation Manual

posted May 31, 2012, 1:54 PM by S B   [ updated Oct 27, 2014, 2:06 PM ]


Chances are you've already seen an installation manual or gotten advice on installation in some form or other. Maybe you've also heard someone who doesn't know what they're doing or has an agenda, talking about how impossibly difficult and/or time consuming the process is and/or how you should have them do it for you. The intent of this manual is to cut through a lot of the talk and present a few simple and concise ways to complete the process with minimal technical experience and tools. There are obviously other ways to complete the process, but the ways presented below meet the criteria for simplicity, ease of installation, and minimal required equipment. 

What your R-hop or ER-hop should look like when you're finished: 

Quick and easy installation technique for the Z-kit covered here:

Standard R-hop Installation:

Installation of an R-hop, particularly the Z-kit, is not difficult but if you're inexperienced is best done carefully. I highly recommend new installers take their time, do not try to rush the process, and DO NOT ATTEMPT TO USE A ROTARY TOOL. A rotary tool (dremel) is an excellent way to remove material quickly, but often times can do so too quickly and/or launch your R-hop into deep space. The recommended materials/tools to complete the process (0:27):

-R-hop (Z-kit preferred)
-Installation Aid
-Sandpaper (400+ grit)
-Utility or Xacto knife
-RTV (sold as "gasket maker" at your local automotive store) or cyanoacrylate 

Step 1 - Check for depth fitment:

Inserting the edge of your R-hop into your barrel window, checking to see alignment with the bore. If you purchased the Z-kit, find the one which is either perfectly flush or a fraction of a millimeter protruding. If you didn't purchase the Z-kit, your R-hop may be too deep and you may need to hold its legs flat against your sandpaper, and remove some height. This can be accomplished in a variety of ways, but holding the R-hop squarely and firmly by one leg while working on the other, then switching, is a relatively easy way to accomplish this. (2:35)

Step 2 - Adjust the length:

Now that you have your R-hop matching the inside of the bore the way you want it to, you need to adjust the length. This is best done with a VERY sharp blade and in a single clean cut. Mark the R-hop carefully, and cut it against a hard stable and flat surface. If you removed material unevenly from the edges, this is a perfect chance to remove that and end up with nice clean square corners. Check to make sure everything fits the way you want it to at this point before moving on. (3:31)

Step 3 - Radius the edges:

While previous iterations of this manual suggested leaving a gap at the front of the R-hop as with the G-hop, it is now recommended for optimal performance you aim for a snug fit in the window and radius the leading and trailing edges of the R-hop to prevent pinch-type jams.  Clamp your installation aid in a vice (or similar, just have it held upright) and use your finger or a thin sliver of something to hold your R-hop in place at the edge of the installation aid. Pinch your sandpaper (400+ grit) around your installation aid rod, and drag it downward across the R-hop edge away from the center of the channel. (4:50

Step 4 - Bond in place:

RTV is less permanent a bond than CA, and also vastly less likely to run, but is an even better gap filler and is preferred for this step. Insert your installation aid rod into the barrel bore. The V.6 installation aid rod is specifically designed to act as a spring, perfectly fitting flush with the bore for exactly this purpose. Wipe a little RTV on the edges of your hop window. Set your R-hop down in the window, then wipe a little more around the edges on the outside. Your installation aid rod will keep RTV out of your bore as well as preventing your R-hop from protruding too far into the bore. You can use the U component of your installation aid to press your R-hop into place and check that everything is the way you want it. (7:44

Step 5 - Cut the outside:

The key to a good install starts with an R-hop that fits flush with the outside of the barrel. After the RTV has cured, leave your installation aid rod in the barrel, and use your sandpaper on the outside of the barrel either in a seasaw motion (Maekii sending method) or forward and backward. Either way the point is the same: your R-hop is being held flush with the bore on the inside, so now you need simply work it flush from the outside. Use care, you should be starting less than half a millimeter away from flush. You can press the U component of the installation aid against the outside surface periodically to see if you have more material to remove. When you're finished, remove the rod from the bore, and press the U against the outside of the barrel. (9:59)

Step 6 - Test:

Press your U component of the installation aid against the outside of the barrel/R-hop, and attempt to drop a BB through. If the BB just falls through, you're done. If it has ever so slight a hint of resistance you may be done or you may want to go back and do a little more. If the BB can't be blown through easily with lung pressure, you need to do more. (11:06)

You're Finished. See wasn't that easy? Wipe the outside clean, and install into your moundless-bucking making sure your bucking is flat and smooth above the R-hop and isn't being squeezed down onto your R-hop in a bad way. Pair with a nice extended nub, such as an M-nubmoundless-bucking 

The Z-kit™; what is different, and what is the same?

The Z-kit is a precise set of different size R-hops. It effectively removes the need to adjust the depth of the R-hop, which is broadly considered to be the hardest and most time consuming step. (part of step1) Feedback from initial testers was immensely positive, new users praising its ease of use and experienced installers praising its streamlining of the process. Since then customer response has been overwhelmingly positive as well, radically cutting the number of questions/issues brought up regarding the installation process. 

Common Problems

I still occasionally get questions/complaints about low accuracy/performance for "no apparent reason." The four most common causes of this are:
Grossly incompetent install -- Issues are usually visually apparent. Show it to one of your friends.

Pinch type jam -- The R-hop pinches between the front of the barrel window and the bb. Radius the trailing edge of the R-hop and keep it off the front edge of the window. 

Low grit finish -- in the guide, working on the channel itself is not part of the process. Never the less, older versions of the guide and many other people's manuals/instructions do suggest doing this work. I had previously recommended 400 grit. Consider this a MINIMUM. The hops prefer even higher surface finishes when possible. They can and do break in with time, so lots of shooting can and will improve the consistency of your R-hop should you start with a low finish. Maekii adds a drop of silicone to his sandpaper to further improve surface finish. 

Hooking of shots -- severe hooking is the result of an asymmetric install, or one of the aforementioned factors existing only on part of the R-hop. It can also be caused by an uneven removal of the bucking mound resulting in uneven pressure on the R-hop. Less severe hooking can be corrected by rotating your inner barrel within the hop unit. After all your gun's vertical is defined by your hop's vertical.

Over-hop -- There are occasions when you can press the U component of the installation aid against the outside surface of the barrel, and a BB will still fall through the barrel, yet somehow over-hop still occurs. This means the problem is external to the R-hop install. A critical distinction of this issue is that the over-hop is consistent, if it is inconsistent you will need to look elsewhere. While there are a myriad of possibilities the most likely are: Bucking improperly de-mounded (modified), bucking too thick/chamber too tight, nub too thick, hop turned too far on, barrel bent (inner or outer), etc.

The R-hop Q&A thread for users who require extra help:


Here are alternate manuals NOT written by Hunterseeker Armory which may also be helpful, some of which are not in English:


Video Pt. 3



Video (English, somewhat exhaustive)