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The Tokyo Marui AK-47 is an age-old workhouse among AK AEG’s. While it has perhaps been superseded by more advanced designs, it continues to be found in many an airsofter’s arsenal for a very good reason. Tokyo Marui has built a reputation on creating airsoft guns that give the Energizer Bunny hives; they simply keep going and going and going….

Recently Rob of Pegasus MilSim fame handed me a newly acquired TM AK-47 to work on. This gun was a Timmy Chang special with upgraded internals and a G&P metal body kit on it with a broken buttstock that sported a large 6″ crack running down the length and a missing buttplate. The goal was to see if I could install some real steel furniture on her and revitalize the beast.

Initially I approached the project with the idea that I would be strictly modifying the real steel furniture to fit the TM. In the end it wound up being a little bit of both….

Lets examine some critical weakness of the TM design:

Being a dependable workhouse does not mean it’s without faults. One of the major design flaws I see with regard to the TM AK-47 is primarily with the buttstock construction itself. It is a large hollowed out space with very thin walls throughout. Essentially this is so it can house a decent sized battery. The TM can of course be wired to the front, as is found on their underfolder versions. I would certainly recommend that most folks wire to the front as you can make better use of stick batteries such as 8.4v – 9.6v NiMH, or 7.4v and 11.1v LIPO’s.

As you can see from the photograph on the above right, the area’s specifically where the tang stock screws affix are very thin – even more so than the vertical sidewalls. By rough measurement, it’s about a 1/4″ thick, albeit less so in the bottom portion. It’s not uncommon to see these areas stripped out or cracked. In this case, two of the screws had stripped the wood out. In the words of the old Soviet saying: “This is weakness!”

Somewhat odd on the TM is the use of what I would call a “reverse tang.” This is a large rectangular piece of hollow metal that extends into the buttstock and acts as a channel for rear wiring. On a real steel AK, the buttstock has a substantial amount of wood that sits inside the receiver, thus facilitating an incredibly strong buttstock. The design of an AEG allows for none of this, however, as the gearbox takes up all available space in the receiver. The reverse tang design means that you can only have very thin amounts of wood for the stock screws to bite into. Rather than repeat this effort only to have it break at a latter date, I decided to instead mill off the reverse tang. The option, of course, exists to rear-wire this by simply boring a hole into the front end of the stock so the wires can pass through.

Affixing the buttstock required that the underside have a slot milled into it to accept the bottom tang and the slot on the top lengthened slightly to accept the top tang. All told there are four screws attaching the receiver to the buttstock. Contrasted against the measly 1/4″ or less of material on the old buttstock, each screw now has over 1.5+” of material to bite into. In other words, it’s very strong now.

The Front End

Modifying real steel forearms to the front also required a bit of engineering to figure out. Again, another critical weakness of the TM design is that forearm has a very small amount of wood (or faux wood, depending on what you have) that fits into the barrel trunion area.

Over a period of heavy use, this can break off or get wore down to the point where it is just a nubbin’. As you can see from the photo of the original forearm, it’s barely there at all. In truth, there is practically nothing except the front mount and the dummy cleaning rod keeping this forearm in place.

Again, rather than repeat the problem, I chose to modify the body kit slightly. I milled off a small chunk of metal to create a hollow space that would be filled with a properly fitted wooden tang that wouldn’t be easily broken.

If you lack a milling machine, this can be modified by cutting on the vertical and horizontal axis with a hacksaw and finished out with a file to clean up your cut. You don’t want to go too far as it will affect the integrity of mounting point for the body screws.

Minor thinning of the rear forearm tang is necessary to make it fit into the metal body kit as it has slightly thicker dimensions than a real steel AK. The front end requires a bit of hand fitting too. Essentially you have to thin it down enough to fit inside the retainer cap. Same concept applies to the wood that fits over the gas tube.

Battery Considerations and Modifications

The TM has a large plastic tray that fits on top of the gearbox that also helps retain the fake charging Unfortunately the design of the tray restricts a lot of the room available inside the receiver for a battery. Attempting to install an 8.4v or 9.6v NiMH, for example, proved impossible as it prohibited the battery from sliding into the gas tube. Removing the tray is as easy as taking out one screw and lifting it away. With it removed, you can now easily slide in 8.4v or 9.6v sticks in addition to the larger diameter 7.4v and 11.1v LIPO sticks. 
handle.

Removing the tray means you will have to figure out a way to retain the charging handle assembly somehow. This is easier than it sounds, however, and if you have a few odd’s and ends’ laying around you can solve it in short order. Simply remove it from the plastic battery tray, taking care to retain the long spring it comes with. Now you can either replace this spring with a slightly shorter one or simply cut it in half. You will need something to prevent the spring from slipping over the crook of the guide rod that the charging handle rides on (it’s also important to note that this assembly keeps the dust cover in place too.) I used a threaded nut with a flange scavenged from an old K-Pot harness to keep the spring from slipping. Basically anything will work as long as it keeps the spring from slipping backwards. If it slips backwards, it can come off the guide rod and render your charging handle useless.

Assemble your spring retainer over the guide rod, then the spring, and then the charging handle in that order, taking care to ensure the guide rod slips into its socket on the front of the receiver. The caveat to this modification is that you won’t be able to retract the charging handle back as far as before. It’s about equivalent to what you get with a Real Sword, though, and you can still access the hop up adjustments.

The Finished Assembly

The final touch was the installation of a real steel AK-47 rear sight. This is a drop-in fit and requires no work to make it fit. The main advantage to this is that you are replacing the cast pot-metal constructed TM sight with a hardened steel assembly that’s designed to carve you an igloo from the frozen Siberian tundra. Overall the feel and fit of the real steel furniture is leagues above the factory offerings, and certainly enhances the overall impression and handling of the rifle.

Since I was making several purchases of various goodies from HunterSeeker Armory, I also decided to add their “Barrel Lockdown Kit” to my shopping cart to give it a try.

The Barrel Lockdown Kit (BLK) is a relatively basic four piece kit consisting of two shims and three o-rings that is designed to do what it’s namesake claims: lock down your barrel to help increase accuracy. By now most should be aware that a wobbly or loose inner barrel to outer barrel fit is detrimental to accuracy. So as such, various designs and techniques exist to keep things as tight and immovable as possible.

Installation

No instructions are provided with the BLK, but if you can’t figure it out, you’re doing it wrong. The main centerpiece of the BLK kit is the conical shim that is designed to replace the traditional brass, plastic, or steel ring that fits in front of your hop up bucking. Typically these rings are usually too loose to do much more than wander back and forth under the AEG’s measly recoil. This can be more of a problem if you swap your stock barrel out for an aftermarket as some designs don’t allow for fitment of those rings anymore. The conical shim pictured here is designed to accept a wide tolerance of barrel diameters and sizes.

An important caveat to the installation of the conical shim is that you simply press it into place. You don’t want to tap it in with a punch or force it too hard as this can cause you to damage your hop up chamber or cause your hop up window and bucking to become misaligned. Simply press it into place with your fingernails and let the o-rings do the rest.

The set of o-rings are supposed to be fitted after you’ve installed the conical shim. On some AEG’s (Ver. 2) you will have a spring on the hop up chamber or one that fits over the outer barrel that helps facilitate a better air seal with your gearbox. The o-rings are there to replace the springs and provide a firmer fit. Technically you’re supposed to experiment a bit with the number required. Too many and you won’t be able to insert your hop up chamber fully into the outer barrel assembly. Too little and it won’t have the desired effect of making things a tighter fit. Additionally these also serve to help retain the conical shim too.

The final piece is the barrel wedge. This is supposed to be installed at the muzzle end of the inner barrel and is simply a wedge to take out any of the slop at the muzzle end area. HunterSeeker5 recommends placing it at the top of the inner barrel as it seems to have the best results for accuracy.

Here’s where things get bad

Considering this is a relatively simple kit with even simpler installation, I have a few complaints:

1.  I do not feel this kit was designed for anything other than a Version 2 design. The design of the Ver. 3 does not lend itself to the correct use of the o-rings. As you can see in the above photo, you can’t fit more than two of these before the outer barrel design makes things too tight. As it is, it’s a pretty tight fit with just two o-rings (they’re almost too big in diameter), and it makes it kind of tough to slap things together. I think over time this will wind up destroying the o-rings actually. You can make it work, but it’s not what I would call ideal. The alternative would be to widen the profile of the outer barrel some where it contacts the o-rings, but this is more work and effort than should be required for some silly o-rings.
2. The barrel shim is too flimsy. I broke mine within seconds of installation – it simply snapped in half. Far too brittle of a material in my opinion. Furthermore, you will not be able to use the shim if your inner barrel is recessed at all within the outer barrel. It’s only designed to work with barrels that protrude past the outer barrel end.
3. At $16 shipped CONUS, this is an exorbitantly expensive kit for what you get. In my opinion the real value lies with the conical shim – that piece does it’s job perfectly and is a good solution for the traditional shims. However, the rest is kind of … the word “blegh” comes to mind. I could source O-rings from the local hardware store for $.05 each and wrapping the muzzle end with Teflon, electrical tape, or fashioning shims from ABS sheet is far cheaper and incidentally, more reliable.

Conclusions

Ultimately I don’t think I would recommend this kit to someone who is looking to lockdown their barrel. The conical shim is the only piece from this kit that I feel has legitimate value (even then, someone with lots of spare time could fashion a similar device), whereas the rest is mostly money wasted. It would be far more preferable if you could purchase the conical shim as a separate standalone piece, but this is not the case. As it is currently, locking down your barrel is an easy proposition with commonly available materials that shouldn’t set you back more than $5.

Introduction

Having experimented quite a bit with various R-Hop designs lately, someone referred me to the Z-Kit from Hunter Seeker Armory as another possible approach to tackling the R-Hop.

The Z-Kit is billeted as a 3-piece kit that is designed to cover most (if not all) hop up window designs out there. Basically you get what I would call a “small, medium, and large” set of contact patches, each of varying thickness. By and large, this set is designed to remove most of the hand fitting required on a traditional R-Hop contact patch. Depending largely on the hop up window design on your barrel, some hand fitting may be necessary. The Z-Kit does not require modification of your barrel itself. Technically it’s a 90% drop in system that may or may not require minor tweaking to the contact patch to make it work properly.

Installation

Installing the Z-Kit contact patch is fairly easy. First, completely disassemble your hop up chamber. Then, select the patch that best fits your hop up window. Typically this is the patch that doesn’t extend past the outer profile of the barrel – rather, it should match the curvature of the barrel as closely as possible. I selected the “medium” sized contact patch for my Prometheus barrel (in this case, a 208mm 6.03 EG). Contrary to a traditional R-Hop patch, no outside profiling or sanding was required to get the Z-Kit to flush up with the outside of the barrel. You will have to cut the contact patch to length. This can be accomplished with a razor blade for the best results, with maybe a little hand filing if you need further refinement.

There are two area’s of thought regarding the cutting to length of the contact patch – one suggests that you leave a slight gap at the forward edge of the patch to prevent “pinch jams.” The other is that you cut the patch to the exact size of the hop up window. I can honestly say that either approach works, the only difference being you get a slightly larger contact surface if you choose the latter. I have yet to experience a pinch jam myself, nor do I expect to. One note of caution: if you leave a small gap at the front, I found it is important that you glue the patch down as the passage of BB’s will eventually pull the contact patch forward and potentially cause patch shifting and problems.

Additionally, you need to slightly radius the forward edge (the part nearest the muzzle end) as a preventative measure against pinch jams. With the wide tolerances in ammo today, this makes prudent sense.

It should be noted that you still have to use a standard hop up bucking the the Z-Kit design – or any R-Hop design for that matter. Technically speaking, you need a modified hop up bucking that has had the locking spline and the mound removed. Simply take your preferred bucking, pull it inside out, and sand down the spline and mound. After you’re done, pull the bucking right side out again, and install. You want to install the modified bucking with the smoothest side (pick an unmodified side) over the contact patch.

Despite my intuition telling me otherwise, I reassembled the hop up chamber without profiling the inner curve of the Z-Kit contact patch. Using .30g Biovals, I immediately had a severe case of over-hop – this despite the hop up being turned completely off! Back to the work bench….

There are various ways of profiling the inner surface of the contact patch. You best bet is to find a file or Dremel bit that is as close to 6mm as possible. You can also use a shish-ka-bob stick wrapped in 400ish grit sandpaper to do this as well. After much experimentation, I ultimately found best results with a diamond coat Dremel bit. The hardest part is holding down the patch to work on it. One technique that worked decently well was to slightly pincer the patch between my index and thumb fingernails. In the end, about 15 minutes of work and experimentation was necessary to finally overcome the issue of over hop. Basically, I have learned that you want to ensure that none of the contact patch protrudes into the barrel chamber (or just barely, if you’re shooting heavy enough BB’s.) The hop up bucking will apply some slight pressure to the contact patch as well, so you must take this into account too when doing your profiling.

Ultimately, I don’t believe there is an R-Hop design out there that does not require some hand fitting. Considering that every barrel is different with unique hop up windows (some are shallow, some are deeper), it does not surprise. If you are adverse to this, then I wouldn’t recommend tackling the job.

The M-Nub

An R-Hop seems to work best with a nub that provides full contact with the contact patch in as flat a manner as possible. I have experimented with a large variety of different nubs, SCS, Maple Leaf, Firefly, etc. While perfectly serviceable – they aren’t necessarily ideal, especially when you are trying to wring as much accuracy out of this system as possible. Enter the M-Nub.

The M-Nub is basically a rectangular block of semi-soft (unidentifiable) rubber that has an adhesive side. It is designed to fit your nub arm window perfectly and lay against the R-Hop contact patch perfectly flat. To this end, some fitment may be required. I wound up shaving the tiniest slice off mine in addition to filing down one side so it had a slightly narrower profile. You don’t want it to unnecessarily drag on the inside of your hop up chamber window.  

Take note: use of the M-Nub requires permanent modification of your hop up chamber arm assembly. You need to make a flat surface on your hop up arm for the M-Nub to adhere to. On my Version 3 AK hop up chamber, this meant simply filing down the curved section designed to hold a traditional style nub in place.

Total time necessary to fit the M-Nub properly took about 5 minutes. It’s ridiculously simple, actually.

Note: once you’ve got the M-Nub dimensionally correct, it is easiest to remove the adhesive backing from the M-nub and place it into the hop up window with a dental pick, then swing the arm into place (do this step with the R-Hop installed first as you don’t want the M-Nub to drop through the hop up window.) Give it a firm press and it should stick to the arm. Check for smoothness and function. You’re done!

Function and accuracy testing

I was looking to push the envelope with my customized Krinkov, so that is where these two pieces were installed. Prior to the install of the M-Nub and Z-Kit, it sported a traditional hop up bucking design, in this case, a Prometheus Purple.

Internal System specs:

• 400 FPS +/- 1-2 FPS
• Prometheus 208mm 6.03 EG stainless barrel
• Z-Kit
• M-Nub
• Gaurder SP-120 spring
• Prometheus Type E cylinder
• Bioval .30g BB’s

Upon testing, I noted that very little hop up is required. I would venture to say that with lighter weight BB’s you will experience gross over-hop. My experience has shown that R-Hop designs tend to really be designed around heavier BB’s. With .30g Biovals (my personal preferred choice for all my AEG assault rifles) the barest amount of hop up adjustment was necessary to sling the BB’s out on a nice flat trajectory.

Now trajectory is where the R-Hop designs really shine. With a properly installed system you should see much flatter trajectories out to your maximum engagement distance (whatever your setup is capable of doing). The other key area is what I would call shot spread, or grouping. With a traditional hop up design, you will get a fairly large group at your AEG’s maximal shooting distance. An R-Hop will grant you much tighter groups than stock performance. Depending on your setup, you should also see an increase in range.

With the above setup, I was able to achieve 10 out of 10 shots at 100 yards (verified with a range finder) on a target with an approximate width of 15 inches by 15 inches. This appeared to be the maximum effective range capable with this particular AEG setup, though one could reach farther with a bit of over-hop applied. My Real Sword SVD, with it’s own R-Hop design (not the Z-Kit) is capable of much further, but then it is also designed to be a dedicated sniping platform. Full auto groupings were dramatically tighter than those experienced with a standard bucking.

Function-wise, it fed every round for a grand total of 12 midcap AK magazines (150 round capacity.) I did not experience any pinch jams, barrel jams, or unwarranted shifting of the contact patch or M-Nub. Of special note, I did not glue down the contact patch like some folks recommend – rather I chose to let the hop up bucking keep it in place. If I find it problematic in the future, I may consider adhering the contact patch to the barrel.

Conclusions

Overall I am very pleased with the performance and install of the Z-Kit and M-Nub. From the various R-Hop designs I have tried, it has been the easiest to install and required the minimum amount of fitment. I would say that a fully tuned R-Hop that has been custom fitted from the very beginning would probably be slightly more accurate – but this may be apples to oranges comparison and hardly scientific consensus. By and large, however, I am greatly satisfied with the accuracy and range improvements an R-Hop provides over traditional style buckings, and even over a Flat Hop. Moreover, I have yet to read or hear of anyone who has legitimately worn an R-Hop out yet – this despite the design now being several years old now. So as a one time investment, it is easily worth the cost and sweat equity to install one. Provided you don’t mess up your first install of the R-Hop patch, you have enough material to do at least 3 hop up units (potentially even 6 if you cut them in half – though they would obviously require varying degree’s of fitment.)

The Z-Kit and M-Nub are available through Hunter Seeker Armory in addition to several other authorized vendors.

VFC builds what is perhaps the best SCAR replica on the market. Externally they nearly match the real steel version 1 to 1. As an upgradeable platform, they make an excellent choice, as you won’t have to touch the externals at all, save for what you prefer to bolt on the plentiful rails. They have been known to have some internal issues, however, and we will be discussing these issues and how to diagnose them in this article.

The gearbox engine used in the VFC SCAR is a Version 2 design. It does use a few proprietary parts though, and it features an ambidextrous selector switch which can be problematic for some aftermarket purposes. For the most part, you will be well served by the stock internals. Depending on your goals and to get the best performance out of your SCAR, a few tweaks and upgrades will be necessary.

As always, clicking any of the pictures will bring up a larger view.

Shimming and Tappet Plate Interference

VFC uses self-shimming gearsets in their SCAR system. This is basically a conical spring that fits to either side of the gear and is supposed to keep things centered. In theory this works most of the time, but nothing is going to be as good or healthy for your gearbox as a true shimming job. The benefits of proper shimming are more precise gear alignment, quieter operation, and less margin-of-error (i.e. better lifespan.) If your gearset came with spacers, you can use those to help obtain proper shimming height. You may also use the sector gear spring as a 1.5mm spacer in compressed form.

Replacing the self-shimming parts may introduce issues with the tappet plate, however. Upon closer examination, you may see that the tappet plate now binds on the shim and / or the bearing surface. This can cause immediate issues with FPS loss as the tappet plate and air nozzle are not allowed to fully cycle forward and create a good air seal with the the hop up chamber:

Solutions

One remedial solution to the above problem is to file down the tappet plate to where it no longer binds on the shims. This is accomplished by thinning down the tappet plate:

In the case of this particular SCAR, thinning was necessary on the right side of the tappet plate. The red marked area is a rough approximation of material that may need to be removed in order to obtain proper clearance. Slow and steady is the key here. File a little, and check often.

Air Nozzle and Hop Up Chamber FPS Loss

If you need to replace your air nozzle due to damage or wear, it is vitally important you replace it with as close an example to the stock nozzle as possible. The stock VFC nozzle measures approximately 21.16mm in length. If you have too short of a nozzle you will likely run into the following issue:

That little gap you see between the air nozzle and the hop up bucking is responsible for a massive FPS loss in this particular example – it chronoed in at a pathetic 117 FPS. Not good at all.

Here you can also see the support/guide that rides just underneath the nozzle.

On a side note, it is recommended to discard the two set screws housed in the outer barrel – these can cause issues with the hop up chamber not seating back far enough and if cranked down too tight will actually crack and damage the hop up chamber. Obviously a cracked chamber can also result in lost FPS too.

Noisy Gearbox

This is probably the most common ailment to the VFC SCAR, and you will have doubtless read complaints elsewhere on the internet about the awful noise emanating from the gearbox. Besides proper shimming (which goes a long ways
towards quieting down this beast), the problem can be fixed by modifying the motor plate. The design of the VFC motor plate interferes and tends to lift the motor wires to cause height and angle problems. In some cases, this will cause such severe binding as to prevent the gearbox from cycling at all. It’s almost the same as an improperly adjusted motor height screw.

Here you can see the small modification done to the motor plate. This can be accomplished with the use of the ever-handy Dremel. After performing this modification, you should experience instant improvements with regard to noise, angle, and efficiency.

The motor plate seems to be a basic Version 2 design, so if you completely wreck it, it is an inexpensive replacement part found just about everywhere.

This is a general guide for tuning VFC gearboxes.

Pre-tuning

1. Velocity check, rate of fire check.

Bushings:

1. Original bushing removal.
2. Bushing glue removal.
3. Ball bearing install.

Shimming (molybdenum grease is highly recommended for gear lubrication):

1. Grease cleaning.
2. Gear teeth check.
3. Bevel gear and motor gear match. Gear movement inside of gearbox should be no more than 0.2mm after gearbox is closed with screws.
4. Remove spur gear spring, use proper shims to match bevel gear.
5. Sector gear, shim between spring and bushing to match spur gear.
6. Tappet plate movement check. File tappet plate if there is interference with sector gear shim (in the case of the SCAR)
7. Close gearbox with all gears, piston, cylinder and tappet plate installed. Make sure it closes tightly without force.
8. Rotate gears and check if piston can be pulled to the rear of gearbox smoothly
9. Attach motor for gearbox test WITHOUT cylinder, tappet plate, piston, spring, and spring guide.
10. Adjust motor height for best result of noise

Air compression

1. Check compression of piston, cylinder and air nozzle. VFC normally has an excellent air seal.
2. Clean and lubricate if there is air leak. Use Silicon grease only for o-rings

Gears, Pistons, Springs, and other Parts

I don’t wholly consider it necessary to replace the stock gears in most AEG’s unless they’re truly awful. VFC gearboxes, for example, (including gears) are designed to be M150 ready, and have been tested with a 12 volt car battery at room temperature. My current setup is running a Guarder SP-110 spring, and is shooting at just under 400 FPS with .20g BB’s.

Out of personal preference, I have replaced the motor on my SCAR with a Tokyo Marui EG-1000. These motors are very durable, quite, and simply run and run and run. Not really a necessary swap, just personal preference.

Most internal parts are standard Version 2, and finding upgrades is relatively easy. Unfortunately, a few of the main components can be a lot harder if not impossible to upgrade. These parts are the ones made from clear polycarbonate and include: the piston, the tappet plate, selector switch plate, and the hop up chamber. With the exception of the hop up chamber (which is truly proprietary), you can find aftermarket parts that can be modified to fit if you’re patient and willing to spend the time and money searching. For the most part though, VFC spares are inexpensive and relatively easy to find and it isn’t really worth the expense to source parts that need modding.

Acknowledgements

Much of the technical information, VFC tune-up guide, troubleshooting tips and the internal gearbox photos contained herein are graciously provided by Sonic who has spent many tireless hours mastering the VFC. Without his help, much of this would still lie in the realm of mystery 😀

We’ve talked before about AEG performance mods, and the role the hop up bucking plays. I’d like to introduce one my personal favorites: the Prometheus Purple (soft type).

I’ve been using this bucking for several years now, and it has rapidly become one of the first AEG upgrades I reach for. It has in some circles reached legendary status for its out-of-the-box performance. In my own circle, there’s not an AEG in my arsenal that hasn’t had at least one Prometheus purple bucking it at one time or another – most are still outfitted with one. Some of my oldest AEG’s are still running the first install, despite having many countless thousands and thousands of rounds through them. Actually, I haven’t worn one out yet, except for one or two instances where I’ve destroyed one prying it from a very tight hop up chamber. I keep several spares in my field kit at all times – though I haven’t had to reach for one yet. Obviously this bucking works very well when paired with a Prometheus brand barrel too.

Prometheus makes many types of buckings, but the soft type Purple is perhaps their best. I would say it’s slightly softer than a stock KWA or Real Sword bucking, but not nearly as soft as a Guarder Clear (which is another great bucking), and certainly a bit harder than a stock Tokyo Marui bucking. It’s in that “just right” category, really. I generally disfavor very hard buckings myself; mostly due to poor performance in inclement weather. Softer buckings tend to wear out faster obviously, but I feel this is offset by the gains in performance. And as an upgrade, a bucking is one of the cheapest parts you will purchase in your AEG’s performance upgrade cycle.

These may or may not run a bit tight depending on your hop up chamber. With most Ver. 2 style hop ups, they seem to fit fine, whereas the Ver. 3 seems to be a bit tighter. In some cases, you may have to trim them for length to be able to affix the barrel retainer clip properly. A sharp razor blade does the trick, and doesn’t affect performance in any way.

I have experimented with different nubs in conjunction with the Prometheus bucking, but it seems to work the best with the one it comes with, although it is quite forgiving with what you pair it with. This bucking is also a good platform to use for building your home-brew flat-hops too. I once relegated this type of experimentation to KWA hop ups, but even in that modified state the KWA hop up is still a disappointing piece of crap.

These buckings can be a bit of a pain to find – few US retailers actually stock them (or have them in stock), and they typically run about $11 – $16 each.

Performance Rating – rating key areas on a scale of 1 – 10, 10 being the best: 

Fit and Finish – score 10. This is a high quality molding. There’s no seams, rough edges, pock-marks, or unwarranted flashing. These bucking’s have always arrived in a soft pliable state, and I’ve not yet received one that has been dried out or torn.

Install – Score 8. With the obvious caveat “No two hop up chambers are alike”, install is generally 90% of the time a drop in fit.

Performance – score 8. I would personally rate it higher, but I’ve also seen greater performance from other types (custom types.) To be more concise, I would say this bucking would rate a 9 or 10 over a stock bucking, but in the face of competition from a custom installed flat-hop, R-Hop, or any of the like, it may fall behind in final performance. If you don’t want to spend time on a custom bucking (and the hours of fiddling and fussing getting them to work just right), this is the way to go, however.

Lastly, be aware there are other factors involved in accuracy and range, not the least of which is what is going on in the heart of your gearbox.

Durability – score 9. I simply haven’t worn one out yet. I have damaged one pulling it from a very tight hop up chamber, but that was because I was being very forceful. Any other bucking would have suffered similar fate, actually.

Price and availability – score 6. A lot of folks complain about the price on these. They are more expensive than most buckings, yes. But I’ve generally noted that the end performance makes believers out of even the most die-hard naysayers. For the truly cheap bastards, nothing will really appease them unless it’s simply granted for free.

Conclusions

While there are a few other buckings out there that may provide better accuracy and range gains (somewhat subjective depending on platform), for an excellent general-purpose “first upgrade” that will give marked improvements on range and accuracy without extensive installation or grief, I would definitely recommend the Prometheus to anyone.