Airsoft Canada

Go Back   Airsoft Canada > Discussion > Upgrades & Modifications
Home Forums Register Gallery FAQ Calendar
Retailers Community News/Info International Retailers IRC Today's Posts

Why do I need to upgrade (or not) - with explanations!


Upgrades & Modifications

Thread Tools
Old November 2nd, 2003, 20:45   #1
Skruface's Avatar
Join Date: Jan 2002
This is an article I wrote for Manitoba-area airsofters, and posted on our D-board. I have posted this in the hopes that some of new players will take a look at it before asking "WuT duz a Silinder H3@d do??!1oneone"


A lot of people saw my AK last Sunday and asked a lot of questions about what was done to it. I've always been a believer in the philosophy that CONSISTENCY is the key to being a good shooter, whether it's live ammo, bb guns, archery, whatever. If your AEG reacts the exact same way every single time you pull the trigger, the shooter should be able to compensate for everything else (crosswind, shooting downhill, etc.) If you KNOW your gun is going to put a bb in a certain place every single time, a skilled shooter can adjust for anything else.

The purpose of this article is to explain (primarily for newer players) what was done to the gun, and why. I'll start by outlining the parts that I think are the most critical, along with their function, and their relative price.


1) The Cylinder Head:

The cylinder head is one half (the stationary half) of the compression cycle of the cylinder set. It controls the flow of air out of the cylinder. If it's misshapen, or the o-ring is buggered, you lose compression (and thus velocity and range). The stock TM Cylinder Head is a single o-ring design, made of plastic with a metal "throat" that leads to the Loading Nozzle. I replaced mine with the Guarder Steel Cylinder Head, which has double o-rings. Since it is made of steel (not plastic) it should be harder to warp/deform, and combined with the dual o-rings should give me great compression for a long time. Price was $20 US from Wargamer's Shop: head

2) The Piston Head:

The Piston Head is the moving half of the compression cycle. The stock piston head is attached to the piston via a screw, is made of plastic, and has an o-ring to seal it to the wall of the cylinder. This part is also the one that causes mechboxes to crack, so proper selection is critical. Aftermarket piston heads come in several types: Aluminum, plastic/polycarbonate, or "silent". In addition, most aftermarket piston heads are vented on the face with holes or slots (unlike the stock piston head), which further aids in compression by creating a tighter seal with the walls of the cylinder. Some piston heads also come with or without bearings. The bearings serve to alleviate possible twisting stress on the spring, and also act as a spacer, allowing a little bit more velocity from your spring (since it allows the spring to compress more).

Aluminum or steel piston heads are generally more resistant to deformation, meaning they'll give you a better seal longer. Unfortunately have a nasty habit of breaking mechboxes, especially on M16/M4/MP5/G3 variants (aka the Version 2 mechbox), and especially if you dryfire alot. This is because it is the piston head that strikes the cylinder head (which is butted up against the mechbox frame), and there is no "give" to the impact. I wouldn't recommend them for use with a high tension spring. They run about $20-$30.

Silicone/plastic/polycarbonate piston heads have more "give" and will absorb an impact better than the aluminum ones, but they can deform and/or crack easier, too. These are probably best used with high-tension springs to reduce impact energy on the mechbox. Personally, I'd rather spend $20 to replace a plastic piston head than $80 to replace a mechbox.

Silent Piston Heads (aka "POM" Piston Heads) are cushioned, and thus minimize the impact on the cylinder head. However, you need to use a match silent cylinder head and silent piston head - you can't just mix and match, as they won't fit together properly. They also serve to quiet down your gun, so if you're considering building a surpressed AEG, this would be a good choice. Silent/"POM" Piston sets run about $40-50, but come with the silent piston head and matching cylinder head.

In my mechbox, I've used a Systema Polycarbonate Piston Head with Bearing. It's vented for better compression, will reduce impact stress on my mechbox, and the bearing will reduce twisting stress on my spring while giving me a few more feet per second of velocity. Price: $13 US. head

3) The Loading Nozzle:

The third part of the compression stage, this is the part that links the compression unit (cylinder, piston/piston head, and cylinder head) to the barrel. If your nozzle is leaking air around the cylinder head, you will lose compression, and thus velocity. If you nozzle does not fit tightly in the barrel, again, you will lose compression/velocity as air leaks out around it. A good loading nozzle is critical to consistency, IMHO.

Nozzles come in a variety of materials, metal and plastic. Personally, I think I prefer plastic, since the nozzle actually moves in and out of the barrel, and I would like to believe that plastic-on-metal friction will cause less wear in the long run than a metal-on-metal. Also, it is the function of the nozzle to push the bb into the barrel, so a metal nozzle with a ragged tip could scratch the bb, potentially inducing spin and reducing the consistency of my shots.

I chose a Guarder Airseal Nozzle ($7 US at wargamers) for one major reason: inside of the nozzle there is an o-ring to create a better seal between the cylinder head and the nozzle.

4) The Cylinder:

The final part of the compression unit is the Cylinder. These are made of metal (usually brass, stainless steel, or aluminum) and come ported to match a specific barrel length. They also may be coated in teflon, to increase cycle speed. The most important part about choosing a cylinder is making sure you match it to the barrel you plan to use. If they cylinder port ends the compression cycle before the bb is out the barrel, you're not getting the maximum velocity you are capable of, since the piston will stop pushing air before the bb has left the barrel. Thus, if you want to use an M4-length barrel, get an M4-length cylinder.

IHMO the material of the cylinder is pretty much irrelevent. Yes, brass is semi-self lubricating, and stainless steel is harder (so it should last longer). But that aside, unless you actually get sand and grit INSIDE THE CYLINDER, wear should be minimal.

I chose to order a Systema N-B Cylinder ($10 US from Wargamers), and I got it in Type-0 size, to match the longer barrel I've got for my AK. To be fair, though, it is not yet installed, so I am currently using a stock TM brass cylinder meant for an M16 with no complaints.

*NOTE* There is a cylinder type called a Bore Up Cylinder. This has a larger inner diameter, meaning it can hold more air volume in the same length of stroke. However, it requires a VERY strong spring to work effectively - the Systema M130, which is far too powerful for use in our games. DON'T get the Bore-Up Cylinder, it's a waste of money for 95% of you.

5) The Inner Barrel:

The inner barrel is what stabilizes the bb for flight. The bb is pushed into the barrel by the nozzle, and then the air charge passes through the nozzle and pushes out the bb. There are a lot of misconceptions about barrels which I will try to clear up.

One common fallacy is that a longer barrel automatically = more range. This is an untruth. Range is regulated by velocity and the Coriolis Effect (aka Hop-Up). What a longer barrel WILL do for an AEG is give you a tighter grouping at longer ranges - wheras a stock MP5K barrel (which is very short) might shoot bb's in a roughly 3' circle at 50', a stock M16 barrel (which is significantly longer) will reduce the size of that group considerably. This is because the longer your barrel is, the more time the bb has to stabilize it's flight path before exiting the barrel.

Secondly, the "tighter" the inner diameter (aka: ID) of a barrel is, the more range you will get. A stock TM barrel has an ID of roughly 6.08mm. Since a good quality bb is going to be very close to 6.00mm in diameter, you can see that the bb is slightly smaller than the barrel. This means there is a gap between the edges the bb and the barrel. This extra space allows for 2 things to happen:

a) Some of the compressed air charge will escape past the bb, meaning you will lose compression, and thus velocity/range.

b) The bb has room to rattle around inside the barrel as it travels, skipping off the walls of the barrel. This creates inaccuracy/inconsistency.

Tightbore barrels are available in brass, stainless steel, and TN-coated steel or aluminum (aka TN barrels). These have an inner diameter of between 6.03 and 6.04mm, meaning you'll get better compression/velocity/range, and smaller groupings. Brass is self-lubricating, but is soft and prone to scratching if you're not careful. Stainless Steel is scratch-resistant, but expensive. TN barrels are the most expensive due to the TN coating process, but it does add a friction barrier. I have a longer-than-stock Systema Brass 6.04mm barrel waiting to go into my AK, but even my stock barrel has performed very well when kept cleaned. I chose brass over TN due primarily to the price consideration - a TN barrel is 2.5 times as much, but it's certainly not 2.5 times more accurate. Brass was $24 US, TN was $55 US. Barrels for AEGs

Additionally, you will see a difference if you use a longer "stock" inner diamater barrel on your AEG, but ONLY if you use a matched-volume cylinder. I have included more info on this elsewhere in the article. You can find used stock cylinders and barrels for relatively cheap on ASC.


The other stuff:

These parts can be upgraded more for durability. They won't generally make your gun more accurate, but may increase the rate of fire and/or range.

6) The Piston

Available in aluminum or plastic/polycarbonate. The stock TM piston is made of Nylon, and wears quite well, actually. If you're going to put on an aftermarket piston head, though, I really would do the piston at the same time. Aluminum pistons are denser and more wear resistant, and that's part of the problem with them. If you plan on upgrading your gears, DON'T get an aluminum piston. The wear between steel aftermarket gears (hard) and the aluminum piston teeth (softer) will eventually cause the aluminum piston to wear, and soon you'll have tiny bits of aluminum shavings floating around in your gearbox, getting suspended in the grease and wearing out your plastic internals. This is BAD. On the other hand, the aluminum piston has a little more weight to it, creating a bit of weight-induced motion (recoil, or "kick" if you want). Personally, I think it makes a gun feel a little more "real".

The plastic/polycarbonate pistons come in 2 flavors, generally: Economy and Reinforced. The difference is in the first tooth of the piston. The first tooth is the one that takes all the stress when your gears first start to turn. Economy pistons have a plastic/polycarbonate first tooth, and are best used in stock or lightly-upgraded mechboxes. The Reinforced pistons have a steel first tooth, making them better for guns sporting high-powered springs.

I have a Systema Aluminum Piston in my mechbox currently, along with stock gears. However, I plan on replacing this very soon with a polycarbonate piston, as I plan to upgrade to steel gears. $17 US at Wargamer's Shop. Pistons And Piston Heads

*NOTE* A word of warning about Systema Polycarbonate Pistons - they come in 2 colors (Red and Black). The Red pistons have a problem as the teeth are not the right dimension - the first tooth is about 2-3 mm too far backwards, causing premature wear and in at least 2 cases I know of complete piston failure and mechbox lockup. Systema remedied this error and released the Black piston, but there are still Red pistons out there. DON'T get the Red piston.

7) The Gears

The stock TM gears are made of some kind of aluminum-zinc alloy, affectionately refered to in Airsoft circles as "monkey metal", "white metal" or "pot metal". There's nothing wrong with these on a stock gun. On a gun running a high-powered spring you will find that they wear out faster, because the teeth will malform and eventually strip due to the stress of the higher powered spring.

Upgraded or "reinforced" gears are usually steel or a steel alloy (although I have seen a set of Titanium gears - don't even ask how much they cost). They are made of a much harder material than the TM gears, and thus last much longer under the strain of a heavily upgraded spring. They also come in different tooth patterns, and in different ratios:

Tooth Patterns:

a) Standard Flat tooth pattern means it's the same a stock. It also means you can mix and match pistons. Pistons And Piston Heads

b) Helical pattern means that some of the teeth in certain gears are curved, but that more teeth are making contact with the piston at the same time than on a Standerd Flat gearset. The downside is that it is strongly suggested that you use a matched Helical Piston, and they (and the helical pistons) are quite expensive. These gearsets are meant for ultra-high power guns used in Hong Kong, and are overkill for our games. But hey, it's your money. Pistons And Piston Heads


a) Standard Ratio Gears have the same gear ratio as stock gears. They're just made of a harder/more wear resistant material. Use with any spring.

b) High Speed Gears have a faster ratio, meaning they will increase your rate of fire. High-speed gears should be used with a very mildly upgraded spring (PDI 120% or Systema M100, maximum), or better yet a stock spring.

c) Torque Up/Super Torque Up/Infinite Torque Up gears have progressively lower ratios and will reduce your rate of fire, but provide more torque for compressing a high-tension spring. Good if you want a high-powered, long range (but slow-firing) gun. As a bonus, they also make your battery last longer (more shots per battery) as it takes less juice to get the motor to pull the spring back. Most guns, even running a PDI 170% or Systema M120 spring shouldn't need more than plain old Flat Standard Ratio gears.....or maybe Torque Up gears.

*WARNING* - some bushings (detailed below) do not fit on all gear axles - the "axles" of Systema gears are slightly larger in diameter than those of the stock TM gears.

On my gun I am using the stock TM gears. However, I plan to replace them in the future with a Standard Ratio Flat set from Systema.

8 ) The Motor

TM makes 2 types of motors currently, the EG700, and the EG1000. Many people mistakenly assume that since the EG1000 is newer and has a high number, it's automatically better. This is not the case. My AK47, with a stock EG700 motor, shoots faster than an few MP5's I've used with EG1000's. In many cases, the size of the battery (both voltage and cell type) play HUGE factor in getting the most out of your motor - more on this later. In general, all the information I've found out about these two motor can be summed up in two sentences:

The EG700 has more torque than the EG1000, and thus makes it easier to turn the spring, resulting in more shots from equal-sized batteries. The EG1000 is capable of more RPM than the EG700, and thus can potenetially shoot more bb's in one second.

Getting back to the topic of stock Tokyo Marui motors, they also come in different shaft lengths. Some mechboxes (MP5, M16) use a long shaft, others (AK47, the SIG series) use a short shaft. Thus, an EG700 motor from an MP5 is not interchangeable with the EG700 from the AK47. TM also makes an EG560, but these are obsolete and aren't used in new TM guns anymore. There is a special Custom High Torque EG560 in the FAMAS that gives it an insane rate of fire, but it only fits in the FAMAS. If you are upgrading your motor, MAKE SURE you get the right shaft length.

Insofar as replacement motors go, there are a number of makers. The main competitors are Eagle and Systema. The Eagle motors come in two sizes: 1100 and 1300. These are hand-wound motors with internal ball bearings for smoother/faster operation, and are VERY expensive. Systema also makes 4 versions of their motor: Genuine (slightly better than the EG1000); High Speed; Torque Up, and Super Torque Up. They also come in various shaft lengths to fit virtually any AEG.

Then there are the also-rans: Classic Army and ICS. ICS makes a Turbo2000 motor for their line of MP5's....from all I've read, they are inferior to the stock TM motors. Classic Army used to make their own motors, but people whom I've talked to who have newer CA guns tell me they come with EG1000's now. Take that for what you will.

At this point, I have no plans to upgrade the motor on my AK. It shoots just fine with the upgraded spring.

9) The Battery

There are 5 factors to consider when choosing a battery: Voltage, Milliamp/Hours, Cell size, Cell Type, and internal resistance.

The 2 most often talked about are Voltage and Milliamp/hours.

Voltage is regulated by the number of cells in the pack. TM guns are designed to run on 8.4 volts - the equivalent of seven 1.2 volt batteries linked together. You can increase your rate of fire by adding another cell (bringing the voltage up to 9.6 volts), but this will increase wear on your motor and will usually require cutting up the inside of your gun to make room for the extra cell length.

Milliamp/Hours (hereafter refered to as MaH) is, in layman's terms, the energy storage capacity of the battery. It defines how many milliamps the pack is capable of discharging in one hour. The higher the number, the longer the battery will last - and the more shots you will get out of it. A standard TM Large battery is 8.4 volts - 1300MaH. A Standard TM Small Battery is 8.4 volts - 600MaH. Thus, a stock gun with a stock large battery should be able to fire approximately twice as many shots as the same gun with a stock small battery - which is why I always advocate buying or modifying a gun to take a large battery.

Cell Type is something of a debate - Nickle Cadnium (NiCad) or Nickle Metal Hydride (NiMH)? Each type of cell has advantages and disadvantages.

a) NiCad cells are cheap, readily available at most hobby stores, and NiCad-capable chargers are cheap as well. However, when the run out of juice, they tend to "ramp down" slowly over a long period of time.....your gun will cycle slower and slower over a minute or two and eventually stop as the cells run out of juice. The bonus is you KNOW beforehand when your gun is beginning to run out of juice. Some will argue that NiCads must be fully discharged before being recharged, or else they develop "cell memory" and can never be fully charged again; I think this is bunk, and can show you a number of NASA battery studies which prove this false. However, I do have a discharger function on my charger and use it.

b) NiMH cells are more expensive, but are available in larger sizes (the largest NiCad I've found is 2400MaH; the larges NiMH is 4000 MaH). They cannot be charged fully or properly using a NiCad charger, so you'll have to invest in an expensive NiMH charger right off the bat, too. Additionally, there is no "ramping down" of the power....there is no warning when your gun is running out of juice. One second your gun is shooting, the next it's completely dead. However, NiMH cells can be fully recharged even when half charged several times a day with no ill effects to the battery pack.

Cell Size does play an issue, too - most battery packs are made with one of two sizes of cells: Sub-C (used in Large packs) and AA (used in Small packs). Generally, the larger the cell; the more efficient it's discharge rate. In layman's terms, it means an 8.4 volt LARGE pack should be able to keep up with (or surpass) the rate of fire provided by a 9.6 volt SMALL pack because of the amount of current it can allow to pass. Also, cells with higher MaH ratings tend to have better "flow though" of power......think of your battery pack as if it contained liquid that you wanted to suck out.....would you be able to do it more efficiently through a McDonald's straw (small cells) or a fire hose (large cells)? I've found the rate of fire on my guns rises considerably when attached to a large pack of the same voltage....

The final piece of the puzzle is internal resistance - how well the charge can flow through the battery. Cheap (aka No-Name) cells have a higher resistance, but are cheaper to manufacture (and thus to buy). Brand name cells tend to be available with lower internal resistance but you will pay a premium for them.

All that being said, I run a 8.4 volt, 2400Mah Large (Sub-C) NiCad pack on my AK. It is constructed of low resistance Sanyo Cadnica cells. The low internal resistance and large cell type means I get a great flow of current, and being a NiCad pack means I can charge it on just about any kind of charger. I didn't skimp on my battery, and had it custom built at Prairie Battery in Winnipeg for under $60 - they are located in Inkster Industrial Park and can be found in the phone book. On a related note, Cyclic swears by Radio Shack R/C batteries....

10) The Spring

One of the great fallacies of airsoft is that you have to have your spring upgraded to the max to be competitive. Again, this is an untruth. You can get the same range with a lower tension spring and other efficiency upgrades. Velocity is not the be-all-and-end-all of a good airsoft gun.

A poorly chosen (ie: to high tension) spring will strip gear/piston/motor teeth, crack mechbox shells, and potentially cause serious injury to someone at close range. A moderately upgraded spring will give you more range, but not more accuracy. Spring upgrades do not tend to affect accuracy at all. The higher the tension of the spring, the harder the motor has to work to compress it. Guns with very high tension springs often require Torque-Up gears, High Torque motors, and 9.6 or even 10.8 volt batteries to work consistently and reliably.

In the last several months, many aftermarket companies have come out with their own springs. The tension ratings on these springs tends to be confusing, so I will try and clear some things up before I go on.....

The stock TM spring shoots a .2 gram bb at about 90 meters (285 feet, give or take) per second - a designation known as M90.

Systema makes a series of aftermarket springs rated in tension between M90 and M170, in comparison to the stock TM spring. Obviously, the M170 is adition to destroying the internals of your gun, an M170 spring will shoot a bb in excess of 500 fps and will cause serious physical injury at close range, including broken teeth and hand bones. In Canada, most airsoft clubs only allow a maxiumum of a Systema M120 spring, which gives a velocity around 400 FPS. In addition, M120 and high springs are well known to break stock internal parts, especially the mechbox shell.

PDI manufactures a line of springs rated in percentage of tension in relation to a stock TM spring. Thus, a PDI 120% spring has (theorhetically, anyways) 20% more tension than a stock spring, and *should* give about 20% more velocity.

You can see, then, that mixing up a PDI 120% with a Systema M120 could be easy for a new player, and could have seriously bad ramifications. In Canada, most clubs restrict the use of PDI springs to 170% or lower. The 170% spring gives a velocity of roughly 400 FPS. As an aside, most experienced upgraders will tell you that the Systema and PDI springs are wound differently, and as a result the PDI springs are much easier to install. Also, the PDI 170% and lower springs tend to be much easier on the internal parts (especially the mechbox shell) than the equivalent Systema M120.

Guarder has recently produced its' own spring line designated SPXXX. My understanding is they use the same rating system as Systema, so a Guarder SP120 would be equivalent to a Systema M120....However, I have no experience with these.

There is also Top Power. They have their own rating process which is similar to PDI's, yet from all the info I've found their springs tend to be of smaller wire diameter. The information I've read (and witnessed firsthand) say that the Top Power 190% spring is roughly equivalent to the PDI 170%. However, due to the smaller wire diameter, these spring lose their tension fairly quickly. I've personally seen a brand new, just-installed Top Power 190% drop in velocity from 423 fps to 400 fps IN THE SAME DAY by running 5 or 6 hicaps through the gun. Based on that, I'd avoid the Top Power springs....

Insofar as my own spring choice goes, I went with a PDI 150%. I felt it gave me a substantial increase in range and penetration power (the ability to punch a bb through grass, leaves and twigs; not through people) while still being light enough to use at close range without risk of physical injury to others. Additionally, it is easier on my mechbox shell, and still light enough that my stock motor and gears can still crank it without requiring a 9.6 volt battery or other high-torque gearbox parts. With all my other upgrades, I willing to bet I'm still very close to 400 fps.....Price was around $15 US from WGC: Springs

11) The Bushings

The bushings support the axles of the gears while they turn. They act as a spacer between the gear shaft and the mechbox shell. Stock TM bushings are made of Nylon and coated with grease to reduce the friction on the gear shaft.

Stock TM bushings don't hold up well to upgraded springs. Guns with high-tension springs like PDI 170% and Systema M120's have reported stock bushing failure and castastrophic damage to the internals (READ: SPENDING LOTS OF $ TO REPLACE INTERNALS) the VERY FIRST TIME they've shot the gun. This is a result of the extra pressure from the spring transferred to the gears, and then on to the bushing. Pressure causes friction. Friction causes heat. Heat causes nylon to melt. Get it?

The best way to avoid this is to upgrade your bushings at the same time you upgrade the spring. I mean, seriously, you've already got the mechbox apart anyways, why not play it safe for a few bucks more?

Most aftermarket bushings are made of metal, and there are many different kinds: Bearing Bushings, Metal Bushings, Laminate Bushings.....

a) Bearing bushings have tiny ballbearings inside that hold the gear axle steady. This drastically reduces friction, but only with low tension springs. Bearing bushings have a well-documented and disturbing tendency to explode when used in conjunction with high-tension springs (170% or M120). Nothing like tiny steel ballbearings shooting though your gear and piston teeth to ruin a gun in a hurry.....These bushing should only be used with a stock spring, or at the very MAXIMUM a PDI 120% or Systema M100. You have been warned. They run about $35-45.

b) Laminate Bushings have a metal frame with nylon on the inside (next to the gear shaft). Due to this, they should only be used with light-tension springs. Personally, I think this is a half-assed solution and don't see the point....they'll still fail with enough tension.

c) Metal bushings are usually made of stainless steel or sometimes brass (which has self-lubricating properties). These are often considered a standard upgrade by most knowledgeable gun builders. You can buy many different brands, and all should work with stock TM gears. However, I do know that not all bushings work well with Systema gears, which have a slightly larger axle diameter. You can't use Guarder Steel bushings with Systema Gears - the fit is too tight. Metal bushings run about $20 in Canada.

Since I stuck with my stock gears but planned a significant spring tension upgrade, I chose Guarder Stainless Steel Bushings with Dual Oil Channel. These particular bushings have 2 grooves cut into the inside of the bushing (where it meets the gear axle) that supposedly helps hold lubricant to reduce friction on the gear axle. I figured it couldn't hurt. $12 US from WGC: Parts for AEG

12) The Spring Guide

This part mounts at the back of the mechbox and ensures the spring compresses in an even, linear pattern and does not bend or kink. The stock TM spring guide is made of plastic and fine for use in a stock gun, but will eventually chip or crack under the stress of a high tension spring. Also, spring guides come in different mechbox types - an AK spring guide is much different than an MP5 spring guide. Make sure you get the one that fits your mechbox.

Aftermarket spring guides are often Polycarbonate (better, IMHO) or metal (The best IMHO). Some come with a bearing set that reduces spring twist and bind as it compresses. As an added bonus, the bearing set acts as a spacer, and will increase your velocity slightly (5-15 fps, on average).

Personally, I made my decision based on the fact that I wanted a heavy duty, never-gonna-fail part. I bought a Guarder Spring Guide with Bearing ($12.50 US at Wargamers), and let me tell you, this thing is HEAVY DUTY. It weighs about 4x as much as the stock plastic one, and it's SOLID STEEL. Plus, the spacer helps give a boost to my 150% spring while working in conjunction with my Piston Head (which also had a bearing) to ensure that my spring will never warp, kink, or bend, since I have bearings at both ends. Parts for AEG

13) The Tappet Plate

This often-overlooked part connects the nozzle to the gearset. It is one of two critical linkages between the cylinder set and the gearset (the other being the piston). The tappet plate is the thing that pushes the nozzle forward into the barrel, allowing the nozzle to pick up the bb and make a seal with the barrel. The stock TM tappet plate is made of plastic, and they are not interchangeable between mechbox types. If you have an MP5, you need an MP5 tappet plate.

This part rarely fails, but when it does it's a huge pain in the ass. What normally happens is that the tappet plate will break in half, meaning the nozzle will not move when the gears turn, and thus the bb's will not load. Sometimes, on worn tappet plates, the nozzle can also become disconnected from the tappet plate and get stuck in the barrel as the tappet plate moves back and forth. Again, the gun will not shoot. The worst case scenario is the tappet plate breaks while shooting full auto and smashes the hell out of the now-floating-loose-in-you-mechbox nozzle and damaging the cylinder head, requiring the replacement of a bunch of parts....

I decided to reduce the risk of failure and replace the tappet plate with a Guarder Polycarbonate Tappet Plate. The polycarbonate has greater tensile strength, and should be much harder to break or wear out. $10 US from Wargamer's Shop: Parts for AEG

14) The Hop Up Sleeve and Bucking

This part is universal - all TM AEG's use the same sleeve and hop-up bucking, which is made of rubber The Hop-Up sleeve fits over the barrel, and the bucking is the flexible little round bit that pushes down in to the barrel creating the backspin. Sometimes the sleeve can rip (especially if you don't turn your Hop-Up off before trying to clean the barrel or remove a jam) or just wear out, and the bucking will fall out and need to be replaced.

I bought a few extra of these for the "just in case" factor. However, I did notice the ones I bought were "stiffer" and noticeably less flexible than the stock TM ones. The result is that my Hop-Up, once set, stays rock solid and doesn't "unwind", and my shots seem more consistent, too. I got the Guarder Hop Up Bucking set. ($4 US at Wargamers Shop). Parts for AEG


This concludes the article on what I did to my AK, and why. That being said, I can make some recommendations. For those on a budget, here's what I'd recommend for maximum increased performance, based on price range:

$50 or less - Spring (150% or M100 max - why risk breaking your gun?) and metal bushings.
$50-$100 - As above, plus piston head, cylinder head, nozzle, hop-up sleeve + bucking.
$100-$150 - As above, plus cylinder and 6.04 Brass inner barrel (possibly larger than stock in both cases)
$150 - $200 - As above, plus piston, spring guide, and tappet plate
$200-$300 - As above, plus motor; or gears; or reinforced mechbox shell
$300 - $400 - As above, including motor, gears, and reinforced mechbox shell.
Skruface is offline   Reply With Quote
Old November 2nd, 2003, 21:18   #2
Grim Fandango
Grim Fandango's Avatar
Join Date: Oct 2002
Location: Toronto, Ontario
Send a message via ICQ to Grim Fandango Send a message via MSN to Grim Fandango
This is absolutely GREAT. I was looking all over the forums for this type of information, but now it's all here in one thread. Excellent work Skurface. I just have one questions about aluminum pistons. You say they don't work well with aftermarket gears, but what about stock gears? Would an aluminum piston and stock gears be safe? Thanks.
Grim Fandango is offline   Reply With Quote
Old November 2nd, 2003, 21:28   #3
Skruface's Avatar
Join Date: Jan 2002
Originally Posted by Grim Fandango
I just have one questions about aluminum pistons. You say they don't work well with aftermarket gears, but what about stock gears? Would an aluminum piston and stock gears be safe? Thanks.
I ran an aluminum piston and stock gears all year this year. The problem with aluminum pistons and steel gears is that they are not that same hardness - The gears are harder. There will inevitably be metal-on-metal wear, and with wear you'll get metallic particles as the hard steel gears chew up the soft aluminum piston....

The best combo is still a nylon/polycarbon piston and metal (steel or TM) gears - there is always going to be wear, but would you rather have plastic paticles or metal particles floating around in your gearbox? I haven't had a problem with TM gears and an aluminum piston....yet? But I'll be stripping down my mechbox for end-of-season service in the coming weeks, so I'll update if I find significant wear....
Skruface is offline   Reply With Quote
Old November 3rd, 2003, 01:05   #4
GBB Whisperer
ILLusion's Avatar
Join Date: Jun 2002
Location: Toronto
Some notes to clarify misconceptions based on my personal observations from modifying AEGs:

Aftermarket piston heads with bearings:

The bearings will only serve to add FPS *IF* you are comparing to a piston head without bearings OR any type of large spacer/locknut used to hold the piston head in place (Tokyo Marui is NOT one of these as it uses a large diameter and thick nut to lock the piston head in place.)

When comparing a systema silicone piston head with bearings to a setup using a Tokyo Marui piston head with the stock nut to hold the piston head in place, the Systema piston head actually showed a 7* fps reduction.

However, when comparing the Systema piston head with bearings to the Systema piston head WITHOUT bearings, the bearing setup showed a 15* fps improvement.

The Tokyo Marui piston head, showed a 22* fps improvement over the Systema piston head with no bearings.

The reason for this is simply due to the fact that the bearings typically found on both Systema and Guarder piston heads are physically shorter than the Tokyo Marui nut which holds the stock spring and piston head in place. Therefore, the Marui nut compresses the spring more than bearings will.

As Skruface's article points out though, velocity is not "the key" to having a more accurate gun. CONSISTENCY is the key and this is one of the main benefits of aftermarket piston heads. Chronograph tests show aftermarket piston heads put out more consistent velocity in shots than the Marui one does.

*These tests were performed with a PDI 120% spring. As your spring gets stronger, so will the velocity improvements, meaning at 400 fps, a bearing part will give a 25fps improvement rather than 15fps. Likewise, the weaker your spring is, the lesser your velocity gains from a bearing part.

"Economy" and "Reinforced" pistons:
The Economy pistons do not have a plastic final tooth as stated in the article. In fact, there is no final tooth at all. The only thing there is the slot which allows you to remove the final steel tooth from your worn down piston and slide it into the "economy" piston. So basically, you save a couple of dollars for a part that you already have and don't need to buy again.
Pistons are consumable products. Out of all gearbox parts, the piston is probably the one that goes through the most wear due to the fact that the material is typically the softest material found in the gearbox and the gear rack goes through a lot of wear against harder materials.

So the "economy" version is just a replacement for a consumable product at the absolute cheapest cost. The material is exactly the same as the "other" piston.

SystemA's Red Piston:
The slot for the final metal tooth is about 0.3mm too far forward, not backward as stated in the article.
This problem, however, has been fixed. All SystemA Red Pistons have no problems now.

Helical Gear Sets:
Re-iterated from this thread:

I have heard many different sources make the common misconception of half-tooth pistons being required for helical gearsets.

The truth is, ALL gear sets, helical or not, use full-tooth pistons EXCEPT the Super Torque Up, Ultra Torque Up and Infinity Torque Up Gear sets.

ALL gear sets have a flat sector-to-piston tooth interface.
The *only* helicoid cogs are the bevel gear to spur gear connection and sometimes on the spur gear to sector gear connection.
Everything else is flat.

This common misconception may come from the fact that the Ultra Torque Up and Infinity Torque Up gear sets come ONLY in helical gear formats. (Although the Super Torque Up comes in both flat and helical versions)

The reason why the Super, Ultra and Infinity gears need a half-tooth are because the cog which connects the sector gear to the spur gear is much larger in diameter than lower torque levels - so large, that it's diameter is actually as large as the diameter across the sectored teeth. This larger diameter is required in order to get a high enough tooth count to get the added torque for very heavy springs.

This is a photo of a HELICAL Torque-Up set:

Notice how from this view, the sector gear (top-right gear) looks like a flat tooth sector gear? None of the teeth on that rack are helical. Not slanted. They are full teeth.

Now this is a photo of an Ultra Torque Up gear set:

Notice how from this view, the sector gear (top-left gear) has a full rack of teeth and appears to have no sectored teeth?

Although the sector gear of Super, Ultra and Infinity gear sets look like it has a full rack of teeth around the entire circumference, there is actually a sectored rack of teeth. The rest of the teeth have half cut away and can be seen if you look at the side profile of a Super, Ultra or Infinity gear set. The full gear rack around the circumference is the interface with the spur gear. I hope that clears things up.

To summarize: Half-Tooth Pistons are only required for the Super Torque Up, Ultra Torque Up and Infinity Torque Up gear sets. *ALL* other gear sets besides the two above-mentioned gear sets can use normal pistons. To clarify, these following gear sets can use standard full-tooth gear sets, regardless of whether the gear set is helical or not: High Speed, Standard and Torque Up.

Top Power Springs:
Am I correct in assuming Skruface's referral of the Top Power 170% spring which dropped from 423fps to 400fps in one day to be what he saw happening to my P90 at Operation: Capital Thunder 2 after I blew off 5 hicaps to "weaken the spring?

I believed that the firing of the rounds were the cause of my spring to drop in fps.

That was until I got my own chronograph and realized that the drop in FPS was not due to a softer and more malleable spring material... it was because my initial field chrony tests were performed with my hop up off which yielded 436 fps. But while blowing off the 5 hicaps in an attempt to "compress the spring", I had adjusted the hop-up for that day. My final attempt at the chrony station yielded 406-409fps with the hop-up on.

I can duplicate this effect and can yield similar velocities, even though it has been over one year since that event.

On another interesting note: In a comparison of springs rated to output similar velocities (Top Power 170%, PDI 150%, Systema M120, Guarder SP110), Top Power yielded THE MOST CONSISTENT velocities, followed by Guarder, then Systema and finally PDI trailing the pack.

Bushing Compatibility With Certain Gear Sets
I have also heard that there are particular compatibility issues regarding Guarder dual oil channel bushings with SystemA reinforced gear sets. However, I have not had this problem with four different SystemA reinforced gear sets (Standard Flat, Torque Up Helical, Ultra Torque Up Helical, Infinity Torque Up Helical) and three different sets of Guarder dual oil channel bushings.

I hope all the information provided in this entire thread proves helpful. I've also been meaning to put all the data I've gathered into a guide, but I'm just too lazy to get it started. I'm just adding on to Skruface's work right now, so I'd like to thank Skruface for putting the effort into getting up a well written and concise upgrade guide. This is a great start to getting all that information that everybody has wondered about into one convenient location.
ILLusion is offline   Reply With Quote
Old November 3rd, 2003, 18:47   #5
Skruface's Avatar
Join Date: Jan 2002
Originally Posted by ILLusion
Top Power Springs:
Am I correct in assuming Skruface's referral of the Top Power 170% spring which dropped from 423fps to 400fps in one day to be what he saw happening to my P90 at Operation: Capital Thunder 2 after I blew off 5 hicaps to "weaken the spring?
You would be correct. I failed to take into account that you were adjusting your hopup as you were shooting the rounds. The added friction from the hopup would certainly lower your FPS - I assumed that you had not adjusted the hopup after your initial chonograph bad.

Originally Posted by ILLusion
Bushing Compatibility With Certain Gear Sets
I have also heard that there are particular compatibility issues regarding Guarder dual oil channel bushings with SystemA reinforced gear sets. However, I have not had this problem with four different SystemA reinforced gear sets (Standard Flat, Torque Up Helical, Ultra Torque Up Helical, Infinity Torque Up Helical) and three different sets of Guarder dual oil channel bushings.
The set of Systema Flat Standard ratio gears I tried to test fit on the Guarder Bushings had to be seated with a hammer if they were going to be seated - they weren't simply drop-in. I conferred with a few other sources that said they had similar issues. Perhaps Systema has changed the outer diameter of the gear axles (the tests gearset was approximately 2 years old), or perhaps Guarder has enlarged the axle hole on the bushings? My experience is limited to the parts available way out here in MB - which, to be honest, is pretty slim pickings with such a small player base out here.

Originally Posted by ILLusion
I'm just adding on to Skruface's work right now, so I'd like to thank Skruface for putting the effort into getting up a well written and concise upgrade guide. This is a great start to getting all that information that everybody has wondered about into one convenient location.
I appreciate the assistance, Brian. I haven't had access to the wide assortment of parts, nor have I completed the varied and controlled testing procedures you have. You input is much appreciated - as is catch the errors I made (WRT the Systema piston tooth et al...).

Also note that ALL of the parts mentioned are available through Tru or any other online retailer. I only used the WGC references/pictures because I got most of my parts through Yawn's WGC Group Order #2.
Skruface is offline   Reply With Quote
Old November 4th, 2003, 01:41   #6
Bravo One-Six
Pacification Specialist
Bravo One-Six's Avatar
Join Date: Oct 2001
Location: Toronto
Send a message via ICQ to Bravo One-Six Send a message via MSN to Bravo One-Six
Stickied, and to be archived.. because for once, a REALLY INFORMATIVE contribution has been made to this board as opposed to the farce of unintelligble bable that usually gets pandered.

Thank you Jamie and Brian. Thank you.

"Solving an imaginary world's contrived and over dramatic problems... 6 millimeters at a time."
Bravo One-Six is offline   Reply With Quote
Old November 23rd, 2003, 01:41   #7
Delierious Designer of Dastardly Detonations
MadMax's Avatar
Join Date: Dec 2001
Location: in the dark recesses of some metal chip filled machine shop
Respectfully, I disagree with the parts Skruface chose to categorize as most important parts to upgrade in an AEG.

Cylinder heads, nozzles, inner barrels, piston heads and cylinders have not caused critical failures in my experience. By critical failure I mean damage causing significant damage to other parts and not just poor (or cessation of) shooting performance.

On the issue of cylinder heads:

I have never found a stock one which did not maintain a decent seal to the cylinder. It is doubtful to me that a machined metal cylinder head can improve significantly on the performance of the injection moulded stock one.

On the issue of piston head materials:

I think it's hard to attibute better sealing charactaristics to metal piston heads since a comparatively much softer rubber oring provides an airseal. If a much stiffer support would provide good sealing, you wouldn't need such a compliant rubber seal. As such, it is more convenient not to machine honed metal-metal piston/cylinder seals (a la ringless engine) and use a compliant seal. The only benefits I see in an aftermarket piston head might be porting which may allow the cylinder to fill with air faster when the piston is yanked back on a cocking cycle or reduced impact loading with a polycarb or rubber tipped head.

On tightbore barrels:

In careful benchmark tests with various AEG setups HoJo discovered that an upgraded AUG with very long KN TN barrel and matched cylinder was outshot by a stock FNP90 with stock barrel and power upgraded internals on nearly every ammo type tested (nearly a dozen varieties). Both guns had recently cleaned barrels and were in otherwise good working order. However, it was noted that the FNP90 had a much more solid barrel to mechbox interface so we think that may have a much more strong influence on consistency. In our accuracy study, I measured 10bbs on three different axis to determine their sphericity and how consistent their diameters were. Measurements were made with a digital caliper tested against a NIST traceable gauge block and shown to be accurate to 0.002mm. BBs could be found to be as aspherical as 0.04mm and a typical bb 5.90-5.95 mm in diameter. What does this mean? The inaccuracies in bb manufacturing probably have a greater influence on consistency than an accurately made TN barrel (splitting hairs between 6.08 and 6.04).

On tappet plates:

The worst case scenario is the tappet plate breaks while shooting full auto and smashes the hell out of the now-floating-loose-in-you-mechbox nozzle and damaging the cylinder head, requiring the replacement of a bunch of parts....
Looks like this ought to be high on the upgrade list to me. I have replaced 2 busted tappets now. Luckily their parts did not fall into the gears.

On spring guides:

In my experience repairing AEGs I found that 3 stock spring guides had failed supporting upgrade and stock springs. The result of this failure resulted in plastic shards to disperse throughout the mechbox sometimes jamming gears and causing them to strip. A non guided spring can also jam the piston either damaging the teeth or otherwise siezing the mechbox. HoJo has also reported sometimes replacing broken stock springguides which failed in a similar manner.


In general I think the avg airsofter holds reliability, durability, of paramount concern. Performance improvements are nice, but they should come without mortgaging the car. Hence, one could decide that a moderate upgrade say: spring guide, bushings, PDI %150, tappet is everything one really needs to have a long lasting well performing AEG. Such an upgrade does reinforce the stuff which breaks with the greatest consequence yet provides a good value performance upgrade. High capacity batteries give easily seen benifits (you get to play longer), and they remain useable even as they lose charge capacity (get old) for longer because they at least last for an non negligible time.

Pretty much all the other stuff is expensive icing on a cake which won't get all that much better. ROF and super velocity upgrades come at much higher financial and durability costs. Sexy upgrades like TN barrels and bore up kits provide only dubious benifits. I'd also state that a replacement set of more robust parts by an inept airsmith can greatly reduce the life of an AEG. If you're not mechanically inclined, get someone who is to help you.


Hop up effect should be attributed to the reverse Magnus force not Coriolis but this is just pedantic as hop ups still work even if you name them bucklings.
Want nearly free GBB gas?

MadMax is offline   Reply With Quote
Old November 23rd, 2003, 02:20   #8
Part man, part machine
MMMiles!'s Avatar
Join Date: Dec 2001
Location: Toronto, Ontario
*note to self* contribute to this thread..... uhh, tomorrow
aka the fully recovered airsoft addict formerly known as HonestJohn

Igitur qui desiderat pacem, praeparet bellum.
MMMiles! is offline   Reply With Quote
Old November 23rd, 2003, 10:34   #9
Greylocks's Avatar
Join Date: Dec 2001
Location: Gatineau, Quebec (Near Ottawa)
After trying many things in many guns I am a firm believer in the KISS principle; Keep It Simple and Stupid.

I have never had any performance problems with a PDI 150 and metal bushings in any sized AEG, when all the rest of the parts stay stock.

Since all my guns with one exception have also been using Large batteries I never had any performance issues based on electrical power either.

This means that my average cost per gun is $50 plus regular maintenance.
Greylocks is offline   Reply With Quote
Old February 12th, 2004, 18:44   #10
DonP's Avatar
Join Date: Jul 2002
Location: Edmonton, AB
This is an excellent read, and I have a belated nitpick:

MaH should actually be written correctly as mAh.

Amperes (current) is denoted by a capital "A", and lower-case "m" denotes "milli" in the metric system ( x 0.001) - as opposed to capital "M" which denotes "Mega" (x 1 000 000).

Not sure about the story behind "h" for hour (as opposed to "H") but if nothing else it's standard practice to use the 'h' at least in this context.

EDIT: H is indeed used for 'Henries'. That's probably it.
DonP is offline   Reply With Quote
Old February 12th, 2004, 19:32   #11
Convicted Hacker
midgetspy's Avatar
Join Date: Jan 2003
Location: Edmonton, AB
Send a message via ICQ to midgetspy
isn't H Henries?
My Old Buy/Sell feedback
midgetspy is offline   Reply With Quote
Old February 12th, 2004, 19:50   #12
Join Date: Apr 2003
Location: Charlottetown, PE
Send a message via ICQ to Pipboy Send a message via MSN to Pipboy
Probably. The symbol is suppose to be lower case if it's anything but a name. Except with litres, because "l" looks like a 1. But the name of the thing is suppose to start with a lower case, whether it's a name or not. Like a nueton (N), or millimetre (mm).
Bloody Mess - By some strange twist of fate, people around you die violently. You always see the worst way a person can die.
-Yeah, I got a five inch taint.
Pipboy is offline   Reply With Quote
Old March 10th, 2004, 13:45   #13
Join Date: Sep 2003
one thing i would like to toss into here is that brass bushings are probably a better idea then steel ones, the whole idea of the bushings is so that the bushings will wear and not the gear axle, if you use steel, then the gear axle will wear instead since it is softer then steel where brass does would not. just something my dad was telling me about. (he's a machinist at mac, so he's got the knowledge)
You may have made a mistake and that is understandable we all do it, but IMO it is how you handle your mistakes that determine your character. - Dron_jones
zcereal is offline   Reply With Quote
Old March 10th, 2004, 14:22   #14
GBB Whisperer
ILLusion's Avatar
Join Date: Jun 2002
Location: Toronto
It's true that brass is softer than steel.

So tell us where to find brass bushings as I surely have not seen them manufactured.

There is a reason why brass is not used and I will explain why.

There are different grades of steel, some are harder than others. The gear axles of TM gears may wear down over time, but I'm sure as hell that the teeth would wear down faster than the axle ever would, negating the worry of your gear axles wearing down. This is the first issue.

The second issue is that aftermarket gear sets use steel axles. Using brass bushings would not be a good idea with these gears. Why? Exactly as you have described: because when the brass bushings start wearing down, the gears will wobble... and when they wobble and misalign, they will eventually jam and in a worst case scenario, the bushing will blow out and next thing you know, you'll have gear teeth breaking off and bits flying around in the gearbox. This will completely negate your idea of saving the gears with brass bushings.

Either way, the point of all the metal is to increase wear resistance. Steel on brass may last longer than any metal on plastic, but it will still wear faster than steel on steel. This is why you keep the bushings and gears well lubricated - to reduce wear.
ILLusion is offline   Reply With Quote
Old March 10th, 2004, 17:27   #15
Skruface's Avatar
Join Date: Jan 2002
IIRC - ICS makes brass bushings that come with their reinforced mechbox kit.


My bad, they're copper. Still, softer than steel:
Skruface is offline   Reply With Quote

Go Back   Airsoft Canada > Discussion > Upgrades & Modifications


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Airsoft Canada

All times are GMT -4. The time now is 09:28.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2022, vBulletin Solutions Inc.