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AEG part correspondance (gearbox)

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AEG Part Correspondance



GOAL: Educating the viewer on more efficent and effect AEG upgrading then so prior (cost, type, material of parts, etc).


So what parts do i need per any given gearbox upgrade?


Parts discussed:








Piston Head






General Information


Disclaimer: The issues discussed and addressed below are done so on a theoretical basis. I take no responsibility for the misunderstanding of this guide and its negative affect on your AEG.


General: This guide will discuss in depth AEG (automatic electric gun) gearbox part correspondence. The gearbox types being addressed are version one to six.



• Recent innovations have prompted the production of a new bread of automatic electric gun. The information presented in this guide does not correspond to these guns (i.e. Systema PTW series, etc).



• The information presented below corresponds to most Tokyo Marui, Classic Army and ICS AEG internals. All manufactures listed are listed on a reference and example basis only.



• One should link the appropriateness of their AEG gearbox version with the information above before proceeding.


Audience Focus


The target audience of this guide is the beginning to intermediate viewer. The viewer should have basic articulation knowledge and be familiar with AEG gearbox vocabulary (piston, piston head, spring, etc).


Information Addressed


General information regarding individual part make up in an AEG gearbox will be expanded upon in terms of type, material and other qualities appropriate per discussion. Understanding the aesthetic qualities in coherence with the physical components of each part is the main focus.


Ultimate Goal


Understanding the interaction and working of the individual parts in a gearbox as a whole. The ability to articulate proper means of replacement per circumstance or upgrade is the overall goal (what type of part, what parts, etc).





Bushings/Bearings: The parts (6) that hold the gears in place inside an Automatic Electric Gun gearbox.


Stock bushings vary amongst manufacture. However, generally there are two types of bushings.





Brand(s) w/ Plastic Stock Bushings



Tokyo Marui


Brand(s) w/ Metal Stock Bushing/bearings


Classic Army

G & G

G & P

Airsoft Elite



Above all else, the bushings in an AEG must be metal before considering any other upgrade option (spring, cylinder, etc).




In contrast to metal nylon is mush more susceptible to wear and flex. On the whole, guns with metal bushings will be more durable, reliable, gears will rotate smoother, and the over all lifespan of the gun will be drastically increased.


However, a gun remaining stock can still run for a significant amount of time before the nylon bushings must be replaced, but it is recommended they be replaced.


Once a velocity boost is considered the nylon bushings must be replaced with metal ones.


(i.e. Since, Classic Army Automatic Electric guns come stock with metal bushings there would be no need to replace them. In contrast to Tokyo Marui were the nylon bushings would need to be replaced with metal ones before considering any other enhancement option(s).)


Bushing vs. Bearing


One must determine whether bearings or bushings are a better upgrade option when replacing stock nylon ones.




Bushing: A fixed removable cylindrical metal lining used to constrain, guide and reduce friction


Bearing: A device that supports guides and reduces the friction of motion between fixed moving machine parts.




A bushing is a non moving guide that contains a fixed hole. Similarly, a bearing is bushing that contains a movable ball bearing inside. This ball bearing moves in conjunction with the axle it supports and guides (i.e. gear axle). The movement of the support in conjunction with the axle on a bearing lowers friction better maintaining a higher rate of fire then a bushing.


Bearings should not be used with any gun velocity over 350 fps. Bushings are free to be used in conjunction with any spring velocity.




Most Tokyo Marui, ICS and Airsoft Elite automatic electric guns have 6mm bushing holes in the gearbox. However, some manufactures such as; classic army produce AEGs with 7mm or 8mm bushing holes in the gearbox. Before purchasing bearings or bushings one must research which diameter is appropriate for their gearbox.


6mm, 7mm and 8mm bushings can not be used in conjunction with the same gearbox (i.e. a 6mm bushing can not be used where a 7mm bushing would be used and vice versa).


The only way to increase or decrease the bearing allowance on a gear box is to purchase a new gearbox shell which allows the diameter wanted.


Further elaboration about bushing diameter will be discussed later on in conjunction with gearbox shells. At this time the only relevant information is to understand the after mentioned differences which delegate basic usage in a gearbox.


Bearing Manufacturers


Area 1000







Spring: Allows for the horizontal compression of the piston determining the potential velocity of an automatic electric gun.


Upgrading the spring in an Automatic Electric Gun is one of most common/popular AEG enhancements.


The advantages of a spring upgrade are the ability of being able to control velocity and range. (i.e. increase or decrease velocity/range over the stock manufactures velocity for the desired weaponry).


Velocity Measurement


There are two ways to measure the potential velocity of a spring in comparison to a standard stock spring.


Percentage System

Meter Per Second System



• Most after market percentage system spring manufactures base the percentage measurement from the standard Tokyo Marui AEG muzzle velocity with a 0.20 gram bb (90 m/s or 100%).



• The meter system is a more accurate measurement in terms consistency between gun manufactures (i.e. Classic Army guns typical muzzle velocity exceed 90 m/s. There for, the percentage system does not stand consistent with all stock guns). However, the meter system stands consistent with all springs and is not based off of any stock manufactured spring. It is a system based on meters per second not calculated from a pre derived measurement and based of it like the percentage system.



• Clearing up a common misinterpretation a spring rated 120 % is not read as 120 m/s. It is read as 120 % which calculates to be around 100 m/s.



• However, feet per second (fps) are the common relative measurements used when acquiring spring velocities. the Foot is used in place of the meter to give one a smaller measurement they can relate to (i.e. light years just stands alone as light years. However, to actually understand how far that is a mile measurement can be derived). It’s basically a smaller way of expressing a large number to better understand how large, fast, etc. something is.



• A spring rated 100% does not mean 100 fps and spring rated 120 m/s does not mean 120 fps. The percentage, meter and feet system are all relative measurements that stand alone. However, each can be derived from one another with the proper mathematical calculation in order to due so. (i.e. 2 inches does not mean 2 feet. 2 feet is 24 inches and 2 inches is 1/6 of a foot).



• Theoretical and actual velocity readings will vary. However, the theoretical reading is the best way to acquire a relative idea of potential velocity.





There are a number of manufactures to choose from when deciding upon a new spring.


Manufactures (corresponding measurement system)


Prometheus (m/s)

Guarder (m/s)

Systema (m/s)

PDI (percentage)

Hurricane (m/s)

Deep Fire (m/s)

21 CA (fps)



• The brand is dependent on desired velocity alone. No pre-determined manufacture produces a best suited/higher quality spring over another on a theoretical or material basis. Higher quality springs only exist via better experience with one brand over another, word of mouth and ultimately opinion. Choose the brand and spring that best suite your automatic electric gun(s) needs.



• Generally uniformity between parts is the best suited way to approach upgrades (i.e. To the best of your ability keep all the parts of the same manufacture).




For the most part, the spring velocity will determine further part upgrades needed for best reliability, durability, performance and lifespan of an AEG in conjunction to the spring in use. Generally speaking an AEG with a higher velocity will need increased upgrades over a lower velocity AEG in order to run smoothly.



• Above all else, the bushings must be metal before proceeding to upgrade ANYTHING (i.e. the velocity – spring, gears, etc).




Piston: Part inside an automatic electric gun gearbox which allows for the horizontal movement of the piston head.




Most stock automatic electric guns are manufactured with a standard plastic piston (i.e. Tokyo Marui, ICS, etc). A plastic piston will suffice for a long period of time in a stock automatic electric gun. However, it is suggested the piston be upgraded once a velocity of near four hundred feet per second is established.



• A piston upgrade is NOT a parallel amount of importance unless establishing after mentioned velocity limits or using a tighter diameter barrel



• A piston upgrade is needed once reaching the after mentioned velocity limits because, the added stress of the spring increases stress on the gearbox. A plastic piston lacks the loss of weight many aftermarket pistons have in order to counteract this stress gain for an efficient running replica.



• Also, after market pistons provide the durability needed in conjunction with high velocities. Plastic does not have this durability and is increasingly susceptible to breakage when running higher velocities.





Regardless of material the first issue of concern is the type of piston needed in conjunction with an automatic electric gun.


There are only two types of automatic electric gun pistons.



Helical (half toothed)



• Most manufactures gearboxes are designed to run with a standard piston (i.e. Tokyo Marui, Class Army, ICS, Airsoft Elite, etc).



• All standard pistons are made to be interchangeable with one another except helical pistons.



Further Elaboration of helical piston use over standard will be discussed more in-depth in the gear section. The only relevant information concerning the two at this time is the need in understanding a helical piston is different then a standard piston and each can NOT be used in conjunction with one another (i.e. a standard piston can not be used as a helical and vice versa).




The piston will be subdued to increased stress dependent on the velocity of a spring and tightness of a barrel. There for, to counter act the added stress on the piston a number of piston upgrades are available.


A piston upgrade is a piston which exhibits a durability gain and weight loss over the plastic piston found in many stock automatic electric guns.





Manufactures (polycarbonate)


Area 1000

Classic Army





Polycarbonate pistons are said to exhibit three times the strength over a plastic counter part. In addition they are approximately fifty percent lighter then a plastic piston. The decreased weight of the piston allows for the most efficient rate of fire to be established. Also there will be less stress on the cylinder head and gearbox shell decreasing chances of mechanical failure over a heavier piston such as; plastic or Aluminum. In the end, a polycarbonate piston increases durability, performance and lifespan of an AEG over a plastic piston.



• Some manufactures produce automatic electric guns that come standard with polycarbonate pistons (i.e. Classic Army, etc).





After Market Manufactures (Aluminum)





Aluminum Pistons are heavier then polycarbonate pistons, but the teeth and over all durability is increased in comparison to both plastic and polycarbonate.


• The increased weight of an Aluminum piston will increase the impact on the cylinder head and ultimately the gearbox shell. Caution should be taken when installing an Aluminum piston over a polycarbonate.



• An Aluminum piston tends to increase the stress on the shell of a gearbox making it more susceptible to mechanical failure over that of a polycarbonate.



• Some manufactures such as hurricane have counteracted the added weight gain of Aluminum. This has been done via cutting vents into the side of their aluminum piston to reduce the weight.



• An Aluminum piston with vents cut into it sustains the durability of any standard aluminum piston, but decreases the weight of it.



• Polycarbonate pistons still remain lighter then that of any Aluminum piston with vents cut into it.







Deep Fire


A relatively new innovation to the aftermarket piston market is polycarbonate pistons with full titanium coated teeth. Most polycarbonate pistons offer the first few teeth as a titanium insert but, the fully titanium toothed piston offers all the teeth as titanium. In the end, these pistons offer the same advantages of all polycarbonate pistons but, have the increased durability of the teeth in comparison to regular polycarbonate, aluminum and plastic.


Special Case


As mentioned above most pistons are interchangeable, except for helical. However, pistons exist in the rare that are made specifically for one weapon, gearbox version, brand and/or other special circumstance. One should make them self aware of these occurrences when considering the purchase of a new piston (i.e. Tokyo Marui PSG-1 piston, etc).


High speed






A high speed piston lacks a few back teeth in order to cycle the spring quicker then that of a standard piston. These pistons are rare, hard to come by and should only be used in conjunction with lower spring velocities (i.e. 250 fps – 350 fps).



Piston Head


Piston head: allows for the outward transition of air from the cylinder to air nozzle.





The stock piston head should be upgraded around the same time as the piston.



• However, most Tokyo Marui AEGs require a new piston be bought when upgrading the spring. The spring on Tokyo Marui replicas have an elongated front which helps to better hold the spring to the piston. The stock piston head screws into an elongated part which only works in conjunction with this stock Tokyo Marui spring. There for, once you upgrade the spring you must purchase a new piston on these replicas.



• The piston head can be upgraded with out the need to upgrade the piston.



The special case concerning Tokyo Marui listed above may apply to other manufactures as well (i.e. Classic Army, ICS, etc). One should research the coherence of their stock piston with that of a new spring before purchase.




Polycarbonate (POM)





• Most manufacturer stock automatic electric guns come standard with a plastic or nylon piston head. However, some manufacturers supply a polycarbonate piston head on their stock AEG.



• All piston heads are interchangeable



• Upgraded piston heads come in either polycarbonate or aluminum form. The aluminum versions are heavier. More force on the gearbox shell is created increasing the potential of possible cracking of the gearbox near the nozzle in contrast to polycarbonate pistons. However, polycarbonate pistons are known on occasion to shatter and Aluminum pistons are not known to shatter (break).



Silent piston head






This piston features a plastic head with a rubber bumper on it to cushion the impact on the cylinder head. This serves to quiet the AEG slightly. These pistons are susceptible to same disadvantages as polycarbonate heads; possibility of shattering with the added advantage of silencing the AEG slightly over Polycarbonate or Aluminum.




Upgraded piston heads aside from material contain holes cut into the front face of the head. The advantages of this modification to the piston head are listed below.



• When the piston is traveling forward the air goes through these holes and forces the o-ring on the piston head outwards to create a more successful seal in the cylinder. Decreasing chances of air leakage in the cylinder.



• When the piston is being retracted for the next shot the, the o-ring collapses down into the channel it resides more compact and quickly because of the vacuum created via the holes.



• The spring cycles with decreased friction allowing for smoother movement of the piston head, piston and spring.






Another option to consider is a piston head with bearing(s). Most stock pistons do not come with bearings. However, many upgraded piston heads are supplied with these. The bearing(s) helps in allowing the spring to spin freely when compressing, thereby removing a bit of extraneous force from the system.





Cylinder: part of the AEG gearbox that holds the air used to propel the ammunition.


General Types


NB (non bore up)

BU (bore-up)


Non bore up cylinders in terms of inner volume are the same as most stock cylinders. The inner diameter stays consistent.


Bore-up cylinders have slightly larger inner volumes then non bore up cylinders. The diameter of these cylinders do not stay consistent from one end to the other. One ends diameter is slightly larger/smaller then the other.




• Bore up cylinders should only be used with very long inner barrels (m16 +)



• In addition, they shouldn’t be used in conjunction with any spring rated below 140 m/s.







Nickel plated

Teflon coated



Most stock cylinders are nickel plated opposed to Teflon coated. It is suggested that all Teflon coated cylinders be used in conjunction with a high speed set up. However, both materials can be used safely in non high speed set ups.



Further elaboration on high speed set ups will be addressed in the gear section.



The major advantage of Teflon over nickel is it is smoother and decreases friction between the piston head rubber and the wall of the cylinder. This allows for the smoother cycle of the gearbox internals to be established.


The cylinder is not of any absolute amount of importance to upgrade. For the most part a cylinder upgrade is left to the discursion of the replica owner; taking into account the exceptions listed below.



Exceptions (as mentioned above)



High speed gear set up


Spring velocity of 140 m/s or above


Very long inner barrel




If one finds the need to upgrade their stock cylinder then the after mentioned data should be taken into account when purchasing and the information below should be reviewed. The information listed below is not mutually exclusive with the information listed above.




Hole Location vs. Barrel Length




Unlike other parts in the gearbox the cylinder is not necessarily interchangeable amongst all automatic electric guns. The type of cylinder needed per circumstance can be determined via relationship of hole location and the length of the barrel which the cylinder will reside.




No Hole: 450-580 mm barrel length



4/5 Hole: 364-460 mm barrel length



¾ Hole: 227-430 mm barrel length



½ Hole: 110-170 mm barrel length




The percentage is not the diameter of the cylinder itself. The percentage is the location of the holes in the cylinder in correspondence to barrel length (i.e. no home means no hole on cylinder, ½ hole means the holes are located halfway between end, ¾ means the holes are located in between the half way and an end and 4/5 means the holes are located near one end).



A better understanding of hole location will be gained once one views upgrade choices for their replica.



All cylinders are interchangeable between gearboxes but, for best performance they must be purchased in relationship to the barrel length of the gun mentioned above NOT the gearbox type



Example: the no hole cylinder can be used in a gun with a v2 gearbox and any other cylinder can be used in the same version gearbox. However, if the barrel lacks the appropriate relationship to the cylinder hole location then the performance and velocity may decrease depending upon circumstance.



If the cylinder hole location is drastically incorrect (i.e. using a ½ hole where a no hole is appropriate) then the ammunition being fired may not be sucked back instead of pushed forward. Thus causing a great deal of agony and mechanical failure which could of easily been avoided.






As mentioned above hole and barrel relationship, material and general type stand as separate issues concerning cylinders.


Steps listed in order when purchasing new cylinder


First determine the hole location needed as appropriate per rifle.

Delegate between a NB or BU cylinder type

Choose the material as appropriate





Gears: The parts(3) that allow for the initial movement of the piston.






Automatic Electric gun gearboxes contain three gears.

1.) sector (top)

2.) spur (middle)

3.) bevel (bottom)


All manufacture gear sets contain all three unless stated otherwise.







Flat gears have teeth with ridges that run perpendicular (90 degrees) to the edge of the gear face. Helical gears have teeth with ridges that run slanted (45 degrees) relative to the gear face.






(Viewing gears from the side: teeth orientation)



Flat: | | |


Helical: / / /



The difference between them is that for a helical gear more than two teeth mesh (at least partially). More teeth come into contact with the piston during any one given movement reducing the stress of any given tooth of the gear in comparison to a flat gears weight load.. This is due to the fact that the helical cut allows for a more balanced weight distribution over a flat gear cut. In a flat gear cut fewer teeth per movement come into contact with the piston.


Ex. if an item needed to be lifted would this be better done via one person or a great many (just taking into account mass)? Obviously the more people you have the less weight one individual would need to carry.



Item = 500 pounds



Two people carrying it would need to distribute the weight 50/50 or 250 pounds per each. However, if you had five people each would need to carry only 100 pounds. There is going to be a lot less stress on the individuals carrying the item with more people because the large mass is more evenly distributed into manageable amounts.


This concept is in direct relationship to gear teeth. However, the piston is the load and the gear teeth are the individuals. The more teeth interacting with the load the less each tooth needs to carry to hold it up effectively.



Advantages and Disadvantages (flat vs. helical)



The above concept ultimately decreased the chance of stripping and loosing teeth because each individual tooth has less stress on it vs. flat (i.e. is it easier to carry 20 pounds (helical) or 100 pounds (flat)? Carrying 100 pounds would increase the chance of injury vs. carrying 20 pound).


However, helical gears tend to require a much more demanding set up and have less room for intolerances in the system. Generally, helical set ups have an increased probability of mechanical failure over flat gears. Since, flat gears bit on a flat plan they transfer power on a plan in direct relationship to the motion of the piston. However, the curve of helical gear teeth allows for a more sturdy interaction with the piston requiring increasingly close tolerances over flat cuts. Hence, helical gears do not allow as much room for error within the system as flat gears do before a malfunction occurs.


For springs 130 m/s and below a flat gear set up is recommended. A helical set up is advised in conjunction with a spring above 130 m/s.



Pistons relationship to gear type



It is of the up most importance you follow the below guidelines when deciding upon the proper piston to use in conjunction with any given gear set up.



• Flat gears can only be used in conjunction with a standard piston.


• On the other hand, helical gears can only be used in conjunction with a helical piston.


• There is a third type of gear but, it was left out of the above for less confusion. The third gear type is called all-helical. This type of gear set retains the attributes of a helical gear set but, can only be used in conjunction with a standard piston. Since, the teeth which come into contact with the piston are left 90 degrees while the rest retain a 45 degree slant.


Helical pistons have teeth half the length of standard piston teeth.



Motor Gear Relationship


Torque is the relative amount of motor revolutions it takes to complete any desired mechanical cycle.


All automatic electric guns contain motors to drive the force. The motor contains a shaft with a small sector gear attached to it contacting the bevel gear (bottom gear in an AEG gearbox). The bevel gear turns the rest of the gears in relationship. As the gears turn the top gear(sector) has teeth on it that mesh with the piston. Thus the piston pulls back as the sector gear rotates allowing for the completion of a cycle. Each time a new bb is the fired the cycle is repeated. This whole process sums up the basic mechanical workings of an AEG



(The rotation of the gears and motor shaft to complete a cycle is the only relevant information art this time.)



The amount of times the motor shaft must rotate to cycle the piston varies between gun type and manufacture. The motor rotation is not based on a pre established standard. Some guns may only need the motor shaft to rotate 5 times in order to cycle the piston while other, may need the motor shaft to rotate 10 or 20 times.


( I am not certain on any exact number of gearing cycles in correlation to gun. I am just using the above numbers as an example that all guns have different ratios.)



Types of Gears (pt2 - torque)



The torque ratio is dependent on the extent of stress an AEG is subdued to.



• As spring tension/velocity increases the amount of stress on the system increases as well.




• Standard AEG motors are not meant to handle a large increase in load without mechanical failure (overheating, etc).




In order to counteract an increased load torque up gears were born. Torques up gears allow the motor to adjust the number of shaft rotations per cycle to run efficiently in coherence with an increased load (velocity increase/tension of spring).




Concept explained through example



For example purposes lets say stock guns take around 6 motor rotations to cycle a spring (one shot). So the ratio is 6:1. Stock guns are manufactured to run efficiently so we are going to set 6/1 as our (x) variable. Now let’s say in that same gun we decide to upgrade the spring to something like 400 fps. We just replace the spring and bushings.


Now the gun is still going to run near 6 motor shaft rotations per cycle. However, the new spring tension is increasing the tension and stress on the gear box as a whole (making it increasingly subtle to breakage, since AEG gearboxes are only meant to have so much stress on them).





(numbers for example purposes only)



Stock fps: 200 fps

Upgrade: XXX fps



Regardless of the spring the gun is cycling at around one shot per very 6 rotations of the motor shaft. So by deriving the manufacture ratio (what the motor rev/velocity ratio is meant to be) we can determine the desirable ratio which entails the least amount of force on the gun.


6 / 200 = 1 / 33.3 so about (1 / 33) – desirable ratio for best function


Now we calculate the current XXX fps ratio.



6 / 400 = 1 / 66.6 so about ( 1 / 66 ) – current ratio



Compare the two



1 / 66 is about 2 times the suggested ratio.




Thus the added stress is distributed throughout the gearbox and increases the chance of something breaking.


When you add stress to any object you increase the chance of it breaking or malfunctioning.


So now we add some torque up gears to our AEG.


The torque up gears are going to adjust number of rotations of the motor shaft with correlation to torque up ratio. Let’s pretend the torque gears we are installing adjust the motor to 12 motor shaft rotations per piston cycle.




12 / 400 = 1 / 33.3 so about ( 1/ 33)



compare to the original stock gun



1/ 33 = 1 / 33




Thus the establishment of the same ratio has been accomplished and there will be a very minimal gain on stress of the system as a whole. Since, the now the ratio is the same as the original gun. Even though it contains a much high velocity spring.


Furthermore, torque up gears lesson the load and stress but, in turn decrease the fire rate.



( the numbers and ratios used in the above section are for example purposes only. They are not meant to reflect any real life ratios of an AEG. They are just used in place of variables so the basic concept can better be understood.)




Torques gear set purchasing



Torque gears come in a vast amount of ratio.








• Most manufactures include the velocity range which is appropriate with any given set on the box. Internet retailers will usually include it in the product description.




• Always make certain the ratio is appropriate to run in correlation with your spring/fps before buying.


General ratios


(Standard spring – 120 m/s) - standard torque

(130 m/s +) – high torque


Most manufactures and retailers website include the ratio to spring/ fps state the allowances in form of a chart or description.




High Speed gears


These gears decrease the number the shaft rotations per cycle. In contrast to torque gears these gears will increase the fire rate of an AEG and increase the stress on the gearbox as well. There for, these gears should only be used in conjunction with velocities 100 m/s or below.



• Failure to follow this guideline will end in AEG catastrophic failure. While safe to use in conjunction with lower velocities “deadly” to use with ones higher then recommended.




• User discretion is advised.







All gears are made from some type of metal.




• To clear up a misconception there exist no plastic gears. All AEG manufactures supply metal gears in their guns (Tokyo Marui, Classic Army, ICS, etc), but the quality between metals differ. Stock gears generally have less strength then after market upgrade gear sets (i.e. torques, high speed, etc).








• However, stock guns can run efficiently and effectively on the stock gears for many rounds. The Replacement of stock gears with aftermarket ones right off is not necessary practice in most circumstances.




• Stock guns will run fine until velocities upward 400 are reached. Once in the range of XXX fps + it is suggested the gears be upgraded right off hand. However, for velocities lower it fine to leave the stock gears until they break.







Gear consideration when purchasing


1.) Helical vs. Flat

2.) Torque vs. High Speed

3.) Ratio coherence to desired velocity

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Some good stuff there, rapidfire.



Note to everyone: this forum disallows any discussion on guns (or how to upgrade guns to) above 1j power limit. The numbers in the above posts were merely to illustrate the mechanical concepts and physical properties behind the workings of an AEG gearbox, so please do NOT discuss any further regarding the validity of any of the comments made related to more than 1j (i.e. 100 m/s = 328 fps) power. Posts violating the forum rules will be deleted, and the poster might face suspension as well.

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I live in California and we have had issues with hot guns. We are setting a fps limit now. What is the most effective upgrade for a gun to get it shooting at this 328 mark? Seems like this limit would also allow for longevity in all guns. What is the most distance available at 328fps?

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I live in California and we have had issues with hot guns.  We are setting a fps limit now.  What is the most effective upgrade for a gun to get it shooting at this 328 mark?  Seems like this limit would also allow for longevity in all guns.  What is the most distance available at 328fps?

To get a stock marui gun to shoot reliably at 328fps you just need a suitable spring (1J or M90/M100) and some metal bushes in your gearbox.

No other upgrades will be neccesary.


Personally, I'd also always fit a bearing spring guide and you also might want to use a higher voltage battery as well.


The laws of physics tell us that a BB fired at 328fps will drop 1m in half a second.

1m is about as much as you can compensate for by aiming high or leading the target so you've got a maximum useable flight-time of half a second.


With a muzzle velocity of 328fps and a maximum flight time of half a second that gives you a maximum range of (roughly) 150ft.


TBH, you might think that sucks at first but, having changed to this level in the UK in the last couple of years, it ain't so bad.

At least you no longer need to worry about a BB whistling out of nowhere and taking you out.

It also requires more tactics to get up closer and, when you do engage, the fights tend to be more frenzied.


A lot of sites in the UK restrict AEGs to 328fps but allow pistols and BA rifles to continue to shoot at higher power.

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very good points. That's exactly why we're starting this rule. People would just sit in a corner camping for the entire game shooting a hot weapon.


Do they make a Systema 90 or something with that power, or is that just a stock springs power? 150ft is darn good for CQB

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Systema make decent metal bushes. You'll also need new shims too. Systema sell them too. Forgot to mention shims before.


Systema sell a 1J spring (which is what 328fps with 0.2g BBs equates to).

I like Systema springs but a lot of people don't cos they're kinda spindly but quite a bit longer than other springs. This means they can be a bit of a bugger to fit.


Other springs have titles such as "M90" or "M100" an M100 spring should shoot at 100 metres/sec which is, near enough, 328fps.




Some spring manufacturers rate their springs when used with 0.25g BBs instead of 0.2s.


If you fit a Hurricane M100 spring, for example, it'll shoot at 100 m/sec with 0.25g BBs but it'll shoot at about 370fps with 0.2g BBs.


You need to find out what weight BBs your site will be using to test guns and then buy a suitable spring. Check with the spring retailer what weight BBs it should work with. An M90 spring will usually give about 315fps with 0.2g BBs.


It's a bit confusing, right?


TBH, I wish everybody would stop using fps to measure power cos it all depends on BB weight.

Far better, IMO, to use the Systema system and rate the spring by POWER.

A 1J spring will always produce 1J muzzle energy. This means a 0.2g BB will shoot at about 328fps and a 0.25g BB will shoot at about 270fps.


Nothing is ever simple, is it? :D

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The laws of physics tell us that a BB fired at 328fps will drop 1m in half a second.

1m is about as much as you can compensate for by aiming high or leading the target so you've got a maximum useable flight-time of half a second.


With a muzzle velocity of 328fps and a maximum flight time of half a second that gives you a maximum range of (roughly) 150ft.


Umm... You completely negated the effect of Hop Up and didn't take into account that the BB slows down very quickly. As an example, a 0,2g bb shot at 130m/s will travel 100m/s after 10 metres. This was measured by shooting over a chrono from 0-10 metres.


I have yet to see a 1 joule gun shoot any BB to the distance of 150 feet in 0.5 seconds.


Despite the error in your theory, I agree that about 150 ft is a realistic effective range of a 1 joule gun.



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Umm... You completely negated the effect of Hop Up and didn't take into account that the BB slows down very quickly. As an example, a 0,2g bb shot at 130m/s will travel 100m/s after 10 metres. This was measured by shooting over a chrono from 0-10 metres.

I agree.


However, I find that the bad effect of the BB slowing down and the good effect of the hop-up seem to just about cancel each other out. I was trying to keep things simple for the guy.


I've done a LOT of calculations and tests to check all this stuff out.


I've always found that the 1m drop and half-second flight time are a couple of pretty good benchmarks.


S'funny. When people ask me about the maximum range of a gun I'll say "about 30-40m" and everybody goes "Huh? Is that all? My guns will shoot much further than that!" but, when challenged, I've yet to stand 50m away from anybody with a 1J AEG and have then hit me with a SEMI shot.

Realistically, about 30-40m is the maximum range you can make aimed shots at.


After that, you can volley your shots and walk them into a target to gain another 10-15m range.


That adds up to about 50m maximum range, or 150ft.

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Rapidfire, nice guide! I glanced through it quickly and though a few clarifications might be in order:


1.) The Systema silent, or AERO piston head only works with the Systema cylinder head, which has the appropriate cone shape cut. Using it with any other cylinder head will result in either piston or gear failure.


2.) Most stock cylinders aren't nickel plated, bu rather polished brass. Guarder makes black chromed cylinders, Systema makes plated and teflon coated cylinders and KM makes teflon coated cylinders, to mention a few.


3.) Guarder pistons work with the stock TM piston head since they have the locking hole for the stock spring retainer cut to the front face of the piston.

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+1 and a few beers next time I see them for anyone who can tell me where to buy 7mm bushings (not bearings).


Just don't like the idea of little steel balls potentially flying around my gearbox.


Very informative guide thank you.+1

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Romulan, you can use a 363mm barrel in your M15 just fine.


DarkAngel, I suggest you contact a local gunsmith / machine shop about making them. They're quite easy to turn on a lathe and shouldn't be too expensive.

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Hi guys, sorry if this question has been asked already (searched to no avail)


My cyma 028S came pre upgraded with metal bushings and an air tight piston. I was wondering, would an m90 328 fps spring kill it or dramatically shorten its lifespan.



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+1 and a few beers next time I see them for anyone who can tell me where to buy 7mm bushings (not bearings).


Just don't like the idea of little steel balls potentially flying around my gearbox.


Very informative guide thank you.+1

7mm Bearings are MUCH stronger than 6mm ones and are suitable for gearbox use.

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There's a good chart for bearing load capacities. Roughly: 7mm bearins are around 50% stronger than 6mm and 8mm twice as strong as 6mm bearings. Other properties that affect bearing life are material, grease, construction, tolerances, installation and the platform they're mounted on.


Keep in mind that in this small scale, even a 0,01mm of play or axial movement has a tremendous effect on bearing life.

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Very-very nice article and very useful for someone is starting.


I would like to be sure about info i collected from web about motors use.


LONG type are for: M4A1,M16,MP5,G3,P90???????????????


SHORT type are for: AK,AUG,G36??????????????????????


PLEASE be careful THE ABOVE are questions..... not a report!!!!!


What about other popular guns?? Which motor type are using??


It can be very useful: a post with detailed info about which gun is using which motor.

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Marui's motor types:


LONG: M16s, G3s, MP5s, P90s




SHORT: AUGs, AKs, G36s, M14s, Thompson


The UZI uses a special short type motor that spins counter clockwise and has a special pinion gear.


The Type 89 uses a new EG1000BT which is the same lenght as a normal EG1000 long, but has a different collar.

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