Guide To (highly) Increasing Rate Of Fire on AEGs

Discussion in 'Gun Building, Modifications & Repairs' started by AirRattle, Nov 26, 2013.

  1. AirRattle

    AirRattle New Member

    How do I increase my rate of fire?

    This is a fairly easy question to answer, so I will go over some basic ways to increase your AEG’s rate of fire. Rate of Fire hinges upon several aspects: Motor, gear ratio, battery, gearbox efficiency, and your gearbox load (how much it is pulling back).

    So depending on what kind of rate of fire you are looking for your set up will vary. If you would just like 25 BPS, for example you may only need a a quick motor (motor choice will depend on your load) / a MOSFET / And an 11.1v battery, and a tune up.

    So let’s start off by going over the basics.

    MOTOR: AEG motors are classified into three basic types: High Torque, High Speed, and a mixture of Speed and Torque. Speed motors are phasing out - they used to be all the rage back when people were running G&P M120 (16TPA-ferrous) motors on m90-m100 springs on their uber-fast full stroke set ups, they are often ferrite magnet motors or low TPA neo-magnet motors. For sheer practicality you will want to go with a high torque motor with 16 TPA or more, depending on your spring / gear ratio set up.

    Examples of Good High Torque Motors:

    Lonex A1 / A2 (16 TPA) / (Supposedly 20 TPA)
    SHS High Torque (16 TPA)
    SHS High Speed Motor (Purple) (14 TPA)
    ZCI High Torque and Balanced Motor (22 TPA / 20 TPA )
    JG Red / JG Blue (16 TPA / 22 TPA )
    Tienly GT-35000 or 40000 ( ? / ? )
    G&P M160 / M170 / M180 (16 TPA / 16 TPA / ?)


    You will need a high quality battery. Most likely you will be using a LiPO battery. Be sure to get a LiPO with a ‘C’ rating of 30 or higher. Get the largest capacity (Mah) you can get. Despite the looks - You may have to run your battery externally, despite sacrificing the looks you'll still get nod from other techs in the field. Your voltage rating 7.4v, 11.1v, or 14.8v will depend on RoF you want.

    An 11.1 15C 1000 Mah Buffer Tube LiPO will not cut it. Batteries like these will kill the performance of any AEG and starve your AEG motor from needed amperage.

    To be honest, avoid purchasing LiPO batteries at airsoft websites. Pick hobby stores as they will have higher quality LiPOs at a fraction of the cost.

    Deans Connectors / Clones: Convert your battery and your AEG over to Deans plugs or Deans clones.

    MOSFET: Yes you need to have a MOSFET. A MOSFET will allow you to run high voltage, high output batteries as well as increase electrical efficiency and remove any heat and resistance in your trigger contacts therefore preserving them. It is a good idea to run a MOSFET regardless of what set up you have. MOSFET systems range from basic, which is really all you need, to computerized fire control units-giving the user the ability to change the functionality of the AEG firing system.

    Popular High Quality MOSFETs:

    BTC Chimera and Spectre
    many more powerful Fets out there.

    Just to name a few.

    Low Resistance Wire: Switching over to Low-Resistance 16AWG wiring will increase your AEGs efficiency by allowing more current to flow cutting down on heat and resistance. There is really no point in any other wire gauge other than 16, 14AWG is overkill and will not really improve efficiency, and 18AWG is getting too small for high performance (high RoF) AEGs


    You will need a piston with either full metal teeth rack or a half rack of metal half plastic tooth rack (You can of course get away with running one metal release tooth on the piston, but who wants to cut the piston and move it back after Short stroke?) If you are going for mega-high speed it is may be best to get a full metal rack piston. Make sure the piston is as light as possible. Drill holes through it “swiss cheese” and do not place any thrust bearings or washers on your piston head because they add weight. Bearings will not be necessary on the piston head as long as you have ball bearings on your spring guide, you’ll be OK just make sure the spring can rotate freely within the piston without the bearings. Piston material choice for high speed will be Nylon and POM because they are light-weight and they absorb impact well-which you’ll notice a lot of Polycarbonate (PC) pistons crack in the front but can still certainly be used.

    A Few Good Pistons Options:

    SHS 15 Metal Tooth Piston
    SHS 7 Metal Tooth Piston
    Lonex / Bravo / ASG Red Piston
    Lonex / Bravo / ASG Blue Piston
    AIM TOP Full Metal Rack Piston
    MadBull PX Full Metal Rack Piston
    ZCI Full Metal 15 tooth Rack Piston
    Magic Box POM Piston
    System Super Core

    Piston Head:

    The Piston Head should be plastic always avoid Metal Piston Heads when building a speed gun - metal PHs are already starting to phase out. As long as it is plastic and seals well, use it. Use your stock one if you can. :D

    Bushings and Bearings:

    If you are using a gearbox that is 8mm or 9mm- you can run bearings, but when using them bit is wise to install a solid steel bushing under the spur gear, unless you are running Modify Ceramics: which are currently, the best bearings you can get. If you have an 8mm Mechbox you can still run solid bushings as they are still more reliable, but you do sacrifice efficiency and there for some speed. If you are using a 7mm or 6mm gearbox shell, your only option is to run solid steel bushings; even if they are packed in grease, bearings will be too unreliable at that size. Be sure to grease your bearings with PTFE thickened silicone grease.

    A Few Quality Bearing Brands:

    Modify Ceramic 8mm Ball Bearings
    Lonex 8mm Bearings
    G&P Bearings
    Magic Box 8mm Bearings

    Gear Sets and Gear Ratios:

    Always avoid “High Torque Gear Sets” the only time a HT gear set is acceptable is in a DSG build and it is only a 20:1 by RiotSC. Now that you have a MOSFET, low resistance wiring, Deans Plugs, and a Neodymium Magnet Motor. It is important to install gears with a ratio of 16:1 or lower. *You can run 18.72:1 and still achieve 30 RPS. Common ratios for high speed: 16:1, 15:1, 14:1, 13:1, and 10:1 - The lower number being higher speed of course.

    -It is important to note that the high speed ratios will put more stress on the motor and battery; the lower ratios really won’t be an issue, but will only increase your speed, now that you have a high torque neo-magnet motor and high discharge, high Mah 11.1v or 14.8v battery. You could have a case of diminishing returns from a lower ratio when you are running say a 10:1 DSG on an M170 Spring, in which case a super high torque (low speed) motor is necessary I.E. FT (Frankentorque) or JG Blue (JGM-42) or the ZCI High Torques that do have 22 TPA. Versus running a much faster Lonex A2 on a 14:1 DSG using the same spring.

    On the subject of gears and high speed, you will always want to short stroke your sector gear to prevent Pre-Engagement. This involves grinding off teeth from the pick-up side of the sector gear. It also involves running a heavier spring to not only compensate for the FPS loss you would experience in a short stroke but it also further prevents PE (pre-engagement) and over-spin. However many teeth you decide to shave off really depends on the speed and your target FPS. Short stoking the teeth off of the piston is not necessary, but if you do, it cuts down additional weight slightly.

    Double Sector Gears: Siegetek Concepts is very well known for their DSG-Dual Sector Gears, they are also known for producing the best AEG gears in the world, ever. If you can afford them, get them. If you are running an AEG above 40 BBs/ second, it is much more practical to run a DSG; with a DSG you can run a high torque motor that will run cooler and the gears are really not spinning any faster than a low speed SSG (single sector gear). You are just getting two piston strokes per one 360 degree revolution of the sector gear. Note this calls for an M150 or stronger spring.

    This super high speed modification requires a lot of experience and knowledge to perfect and get right, you must know how to shim perfectly and have a good understanding of how each and every part of how the gearbox works and operates.

    A Dual Sector Gear Build can also very in Rate of Fire (RoF) from low speed DSG (conservative and very reliable) to a high speed DSG. I would not say there is any official line between the two that I know of, but if I had to take a guess a low speed would be anywhere between 35 RPS - 48 RPS. And higher speed would be 50 plus RPS. This all depends on motor, gear ratio, spring, and battery just like a SSG would. If you can afford them, would recommend purchasing the entire DSG gear set from RiotSC (Siegetek Concepts).

    To achieve the full advantage of your AEGs RoF or to maximize its potential. You will need to make sure your mechbox is in tip top condition so it will not be slowed down. You will want to make sure your gearbox is shimmed to the best it can be with the shim space you have available. A bad shim job will put more stress on your motor and your gears, RoF and trigger response will suffer, and make your AEG ‘short lived’ especially if you are throwing in high speed components. This is a user error that is unacceptable in AEG builds of any sort. Don’t be lazy, take your time shimming using the bevel to pinion method.

    Correction of the Angle of Engagement (AoE): Most all experienced users are familiar with this if you are not then refer back to the article titled “Angle of Engagement.” The author’s preferred method is through use of a Sorbothane Pad with protective pads.

    Hope some of this information will be useful and relevant :D


    We reserve the right to update this article when needed.
    Last edited: Nov 27, 2013
  2. yattmaster

    yattmaster New Member

    :cough: legacy's guide as of 2 days ago :cough:

  3. AirRattle

    AirRattle New Member

    Oh. Well that is better than mine :eek:
  4. theonlyBuster

    theonlyBuster Active Member Lifetime Supporter

    S. Florida
    Nothing wrong with multiple guides, as long as the information is correct and informative. Plus it gives the tech multiple sources to compare and consider.
  5. Raven1st

    Raven1st Well-Known Member

    San Ramon valley
    I aree with buster, nothing wrong with multiple guides.

    I think that this is a well written guide that would be a great place to start researching high-speed builds.
  6. NeoAugAU-3G

    NeoAugAU-3G Active Member

    Las Vegas
    I see nothing in here about the 11mm tappet mod. Otherwise, good general knowledge for a newer tech.
  7. LegacyAirsoft

    LegacyAirsoft You can say I tech a little...

    I personally see nothing wrong with multiple guides, however it is a little bit fishy how there's came out just days after mine, and a guide on this topic was never created on the forums before...hmmmmm.

    Anyways, mine is much more extensive and covers more topics in greater detail. Found here:

    But, I do like airrattle's approach to their guide. It is an unorthodox way of explaining the subject as a vendor and it was more on the side of "I want to help airsofters" rather than making it seem more complicated to advertise their own services.

    That being said, I do have a bone to pick with the guide. I will keep it short and sweet rather than "ripping it apart" (because, I actually thought it was fairly good, and the information to be fairly accurate), but this quote:

    "On the subject of gears and high speed, you will always want to short stroke your sector gear to prevent Pre-Engagement."

    Is wrong. You do not always want to short stroke to prevent PME. Two reasons:
    1. Short stroking DOES NOT PREVENT PME (it has an almost unnoticeable effect on it, unless you short stroke an unreasonably high ammount of teeth). Adding a higher rated spring prevents PME, short stroking lowers fps and strain to compensate for the higher rated spring.
    2. If you don't need to shortstroke, you are losing volume in your setup for no reason at all, which CAN lead to an undervolumed gun which is a big NONO and will affect range and FPS.
    Last edited: Nov 26, 2013
  8. AirRattle

    AirRattle New Member

    Tank you all for the great feedback :D
    Just from re-reading it I immediately find things I could have worded better, explained better, gave more informative information, etc. I will probably make some of those changes tomorrow. :) So expect to see some minor edits here and there.

    @ NeoAugAU-3G
    Thank you, as for the tappet plate, I assume you are referring to modifying the tappet plate for a DSG? - Otherwise you all know something I don't :)

    @Legacy Airsoft

    I agree! Do not short stroke unless you do not have to and of course you cannot on longer barreled AEGs especially when running heavier ammo. I will be sure to change that. :)

    I should have reworded that - a higher rated spring will of course greatly reduce the chances of PE. But for those who are running over 30 RPS, they may or may not want to run at that high of a velocity from the full stroke.

    The time in which these two posts were written is bizarre. I think mine was much less involved than yours was as I said in the 3rd post. I did not intend for this to happen. I was not even aware that there was one up. I actually wrote this article months ago posted here made some minor edits and decided to throw it up today, hence the reason for me wanting to edit it (update it) again after thoroughly re-reading :) (Initial Edit due to Formatting Issue) when copying it over from a word doc)

  9. NeoAugAU-3G

    NeoAugAU-3G Active Member

    Las Vegas
    While the tappet mod originated for the dsg it is helpful for any high speed build. the 11mm mod, sanding the front, and cutting the spring all help return the tappet where it needs to be to fire quicker. Not a huge deal under 30rps, but anything over that i would do it.
  10. AirsoftShawn4

    AirsoftShawn4 New Member

    Lansing / Webberville / South Lyon
    That TPA list is so jacked lel