CajunAirsoft's M4 DMR Build

Discussion in 'Gun Building, Modifications & Repairs' started by CajunAirsoft, Aug 12, 2012.

  1. CajunAirsoft

    CajunAirsoft New Member

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    Hey guys I currently have a JG m4 Cqb. For right now all I have done to it is shimmed,tefloned my cylinder head and air nozzle. I know i need to do AoE and stabalize my barrel and tune my hop up. My gun is probably shooting in the 400-420 area right now.

    Parts List

    Shs Piston
    16 Awg Wiring
    m1?? spring(need advice)
    Mosfet(which one)
    11.1v lipo (overkill for DMR?)
    new cylinder head
    new air nozzle
    Spring Guide with ball bearings (nessesary?)
    420mm Tightbore (Madbull on a budget)
    Matrix Mock Silencer
    Madbull blue or some other hard bucking
    Deans Connectors

    Externals
    I need advice on what looks good on a m4 dmr. (I hear magpul is getting really main stream)


    I am up for any criticism this is just a list i threw together.
     
  2. Darkrider9

    Darkrider9 New Member

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    Looks like a good start to a list. The spring isn't a huge deal in a DMR, FPS doesn't really effect accuracy or range very much unless you flathop, you do need a fairly strong spring though because you are going to be wanting to use heavy ammo in this. I use .43s and I run with an m140 spring, but I have seen up to m170s used. At that point it gets hard to reassemble the GB though. 11.1v is good, but in my opinion it puts too much stress on the parts. I use a 7.4v for safety, but I'm going to up it to a 9.6 once I get a mosfet and tune up a few more things. A spring guide with bearings is always a good idea, especially with heavier springs. For the piston I recommend picking up a 14 or 15 tooth, but you'll have to shave some to correct AoE. Also I recommend you do the R-hop mod, that will increase your range and accuracy by a longshot.

    As for externals that's where you get to have fun. Pick what you like and don't worry about what others think or if you think it's "mainstream" or not. If you like the look, go for it! It's your weapon after all, build it how you like.

    Good luck!

    Edit: Try to pick up a torque motor too, you need a strong motor to pull back a heavy spring like that. Also you may want some torque gears too. JG makes pretty sturdy gears for a good price.
     
    Last edited: Aug 12, 2012

  3. CajunAirsoft

    CajunAirsoft New Member

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    Thanks for the tips but I heard jg ht motors will pull fine. I'm already running a 9.6v . What fps are you getting with the m140 and sorry forgot to list r hop.
     
  4. EDI1st

    EDI1st New Member

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    Um, fps does affect range and accuracy.
    Just not like what people think.
    Better way to put it is "energy".
    More energy that can be transferred to the BB means that you can use heavier rounds and the BB will have more energy at further distance.

    MOSFET, get the HS5 one, can't go wrong with it :p
    ER-hop is what you need, not R-hop.

    I use 11.1 20C 2200+ mah lipo paired with high torque motor and high speed gear set.
    Torque gears are actually not as useful as you think they are.
    They just make your trigger response longer.

    Plus since you have a JG, you may already have the M42 motor which is one of the torquiest motor in the market.
    It can pull the Prometheus MS210 spring :p
     
  5. CajunAirsoft

    CajunAirsoft New Member

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    I'm pretty sure it is it just says JG high torque if so what spring do you reccomed (I don't want too much fps ). As the HS5 MOSFET you mean the one on clandestine? Is that one a little over priced it's like 75$. Also with the MOSFET and Shs pisto. I should be fine with the 11.1v battery.
     
  6. Darkrider9

    Darkrider9 New Member

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    1. FPS does not affect accuracy significantly. As for range, not as much as you think, there are so many other factors to it other than fps. If there wasn't people would only need a new spring to upgrade.

    2. The HS5 mosfet is a bit overkill for this, there are ones that fit his needs for much less.

    3. ER-hop requires pretty heavy barrel modification, and you'd need to be an experienced tech to do it well enough. And again, it's overkill, R-hop is fine. ER-hop is really only applicable for high power sniper builds.

    4. Torque gears are helpful, yes they do increase trigger response time, but it helps take stress of other parts and that is much more beneficial than the almost noticeable delay. DMR's don't use full auto anyways so it's even less of a problem.

    5. The JG motor is good, but if he doesn't have a torque one it's worth buying it. As for the MS210, can I have video proof please?
     
  7. EDI1st

    EDI1st New Member

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    1. Same hop setting, same rounds, higher fps will have more range....R/ER-hop just gives even more range.....It's basic physics...not hard to figure out.
    Combination of both is the best....really...don't doubt me....I've won international build off for the Best DMR...

    2. That's why I said you can't go wrong with it.

    3. ER-hop gives you extra range, he's building a DMR, not a regular battle rifle. Too much work? It's $30 to have a tech to cut the barrel and install it.

    4. The only stress that high torque gear set removes is from the motor, it only matters when your motor is crap.
    Trigger response has NOTHING to do with RoF.

    5. Proof for MS210? It's all over the forum. Ask Star_Folder about it, he has MS210.



    To OP,
    HS5 MOSFET is $40.
    Spring wise, any spring you want, just make sure that it's within your field's limit.
    Also consider to modify the gun to shoot in semi-auto only.

    Lipo wise, MOSFET, AoE correction, you should be good.
     
  8. CajunAirsoft

    CajunAirsoft New Member

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    Okay sounds good I don't really have a good field around just don't wanna sting my friends too bad .....
     
  9. EDI1st

    EDI1st New Member

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    Well, you can always put an MED on yourself.
    I play a lot in random open lands with no FPS limits.
    I just make sure that I'm FAR when I'm shooting at the guy.
     
  10. Mystery43_4

    Mystery43_4 New Member

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    1. FPS alone does effect accuracy of range, but a higher FPS will raise your range's ceiling. Accuracy can be the same at 300FPS, and at 500FPS. Use a .40g BB at 300 FPS, and a .90g ball bearing at 500FPS, and you'll receive similar results.

    2. The HS5 FET design is good, and Mystical does a good job at making them. I personally make my own micro FET's, throw them in all of my builds and don't need anything more. OP: You are talking about the TerminusX FET. I know nothing about it, but for that price would go with something else.

    3. ER-Hop is easy bro. Any dummy that can use a file and some sand paper can mod the window and contact patch properly. I run my ER-Hops in my basic 400/.20g rifles paired with .30/.32g BBs. ER isn't just for the 400ft DMR's... Although I do have one planned for my LRB'd 715mm Lonex barrel.

    4. I build DMR's with numerically higher ratio's for customers, and numerically lower ratios for myself. I get to enjoy the performance, and their lack of knowledge doesn't always mean utter destruction.

    5.Video's don't = Proof. Any average Joe can throw any armature + magnets into any can they want and say it's an amazing new KWA 3gx motor.
     

    Attached Files:

  11. CajunAirsoft

    CajunAirsoft New Member

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    It looks good but I'm not nessisarily good with that kind of thing. Im all good with gearboxes ,but not so good at guess and check things . How are the r hop z kits? Also what do you guys think on buckings??
     
    Last edited: Aug 13, 2012
  12. EDI1st

    EDI1st New Member

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    The Z-kit still requires you to cut to length, not hard, it's just a straight cut :p
    For ER-hop, all you are doing is making the barrel window longer and maybe deeper.

    Bucking, just any bucking that's not crap and forms nice seal if you want to use R/ER-hop.
    If not, I highly recommend Prometheus.
     
  13. CajunAirsoft

    CajunAirsoft New Member

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    So don't go for the prompt purple if I am gonna r hop.
     
  14. EDI1st

    EDI1st New Member

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    Still go for it, it's a nice bucking.
     
  15. Nelson

    Nelson Review Guru Supporting Member

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    To once and for all end this FPS crap, redwolf did a great article on air time, range, and accuracy. FPS affects the amount of airtime a bb will have, the more airtime a bb can get, the better it's accuracy can become, with that you need a great hop up, hop is what gives you accuracy. If you jar a great hop up unit, your bbs will get the proper spin, and lead to a tight group, now that you have accuracy and airtime, you need range, that's where the length of your barrel comes in, with a longer barrel, your gun will be able to reach further in a nice tight group, I hope this helps.
     
  16. CajunAirsoft

    CajunAirsoft New Member

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    Ahh yes almost forgot . I Just have the standard JG m4 hop up will that work?? To get another I would also have to convert to a metal body.
     
  17. Mystery43_4

    Mystery43_4 New Member

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    Redwolf must not know what they're talking about.

    OP, the stock JG Unit is fine. Just tune it a little bit and you'll get the same performance out of it as any other expensive Unit.
     
  18. EDI1st

    EDI1st New Member

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    Not necessarily true with the longer barrel part.
    440mm is usually the max you need.
    What's more important is the cylinder to barrel ratio.

    Higher fps does NOT give you more air time. Hop does.
    Basic physics....
    When you push something off a cliff, doesn't matter if you pushed it off at 10mph or 100mph it's going to hit the ground at the same time assuming that they land at the same height.
    Gravity is constant at 9.81m/s towards the center of the earth, just saying.
     
    Last edited: Aug 13, 2012
  19. CajunAirsoft

    CajunAirsoft New Member

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    Okay sounds good I will update when I make a final order any other tips or anything still accepted.