Cysko's m4 CQB build

Discussion in 'Gun Building, Modifications & Repairs' started by cysko, Oct 31, 2012.

  1. cysko

    cysko New Member

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    Hey guys!

    I'v finally decided to build my self a CQB gun since i have a few arenas near me that are CQB and my current m4(stock m4 with few mods) is to powerful for the fields FPS limit.

    These are the parts i will be upgrading to.


    Echo 1 high speed gears(13:1).

    Echo 1 sp90 spring.

    Lonex m4 air nozzle.

    Lonex blue piston(will probably swiss cheese it for better speed).

    SHS high speed motor.

    NanoFet mosfet unit.


    Please tell me if i shouldn't use one of these or there is something better out there for about the same cost.
     
  2. alex

    alex New Member

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    Atlanta
    keep your original spring and just short stroke the sector/piston to the desired fps level. you will enjoy the better trigger response. deciding on high speeds depends if your cqb allows full auto games. mine has around 2 full auto games during the night. without short stroking, expect over spin (multiple cycles/shots on semi-auto).
     

  3. cysko

    cysko New Member

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    How do i "short stroke" it?? the original spring does about 430, the limit is 350 so i would need to get a new spring wouldn't I?? yes it allows full auto fire.
     
  4. alex

    alex New Member

    4,794
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    Atlanta
    with an m130 (chrono's ~440fps), -3 teeth on the sector pickup side brings it down to 390 fps. did you chrono it or used the spring rating listed on the package? not too many stock AEG's hit 430 fps. most outdoor field limits are 400-420 fps (full auto).

    removing the first 3 teeth on the sector gear will bring the fps down. if your AEG really is shooting 430 fps, you may need to go -4. when you adjust AOE, you will get minor fps drop.
     
  5. S1kkguy

    S1kkguy New Member

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    Alex knows what he is talking about. That SP90 spring will defo give problems if your looking for a high ROF set up. With a dremmer, shave off x number of teeth, doing them one at a time (by them I mean the sector and the corresponding piston tooth) until you reach your desired FPS. I use a m120 for my short stroke set up.
     
  6. cysko

    cysko New Member

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    yes it has been chroned between 415-440, ok Alex can you tell me how to do this, what i will need, and etc... I have never heard of doing that before and i would think if you take teeth off that it would mess the gun up.
     
  7. S1kkguy

    S1kkguy New Member

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    London
    It's pretty simple. You need a dremel with the disc accessory on.

    NOTE: When short stroking, always make sure the last tooth left on the piston is a steel one, as that tooth takes the most stress. And no short stroking would not mess up the gun if you do it properly, if anything it can increase the ROF as the gears would cycle the piston quicker.

    Now, the last tooth on the piston that would get pulled back by the sectorgear, slowly shave it down until it is non existant, making sure everything is smooth. Now do the same to the corresponding tooth on the sector gear, so the last tooth that would pull the piston. Waa'lah. You have a short stroked set up. I actually just did it on a new set of 13.1 gears i got before typing this. I am using an m120 spring getting it down to 360 fps.
     
    Last edited: Oct 31, 2012
  8. alex

    alex New Member

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    Atlanta
    the proper way is removing the piston teeth closest to the piston head and corresponding pickup teeth on the sector gear.

    i use a bench grinder to quickly remove the teeth. others use a dremel cutting wheel or bit which takes forever.

    415-440 is not a stable air seal. after fixing the air leaks, i recommend a cheap m120 and SS it down to 350 (usually -2 to 3). i prefer SHS 15T. the new SHS 14T (black teeth rack) are off spec and will cause damage.

    don't forget to adjust AOE...
     
  9. cysko

    cysko New Member

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    SS? sorry i dont use text talk a whole lot.
     
  10. schmidty

    schmidty New Member

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    Washington D.C.
    Short Stroke (20 char)
     
  11. cysko

    cysko New Member

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    woops..i should have known that lol
     
  12. cysko

    cysko New Member

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    so any reccomendations on a piston and spring??
     
  13. schmidty

    schmidty New Member

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    Washington D.C.
    Alex said SHS 14T. Many people like lonex red. Go with either, lonex if you have money to spend.

    M120 spring. Guarder makes good springs.
     
  14. TheAirsoftTech

    TheAirsoftTech New Member

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    I've heard SHS is has been having some QC issues lately... So, just to be safe, I'd go with Lonex.
     
  15. cysko

    cysko New Member

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    would Lonex blue be any better?
     
  16. cysko

    cysko New Member

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    what problems would i run into with say a m90 or m100??
     
  17. S1kkguy

    S1kkguy New Member

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    London
    pre engagement..................
     
  18. TheAirsoftTech

    TheAirsoftTech New Member

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    If you go to fast you'll hit pre-engagement, which is when the sector gear engages the piston to early. This usually ends badly.

    Also, you might want to use the edit button.


    EDIT: Sniped.
     
  19. cysko

    cysko New Member

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    Sorry... Also what is defined as pre-engagement?
     
  20. schmidty

    schmidty New Member

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    Washington D.C.
    Lonex blue is not better than lonex red. Why would the regular piston be better than "extreme toughness" (or whatever name they have for red)?

    Pre engagement is where the sector gear begins a new cycle before the piston completes its cycle and will strip or otherwise destroy pistons very fast.

    This is pretty simple: get the M120 and short stroke if you want high rps.