Featured ASG m115 spring with 155mm 6.03 inner barrel

Discussion in 'Gun Building, Modifications & Repairs' started by Big Chungus, Oct 7, 2021.

  1. Big Chungus

    Big Chungus Member

    39
    2
    New York
    Hello, I did post on reddit but would like to pick peoples brains on here. Cqb build in progress, 13:1, 22tpa motor, madbull 155mm inner barrel 6.03. With perfect airseal I am trying to figure out if I should short stroke the sector and piston release side by 2 teeth to stay 350 fps and under. I have a chrono so I can spring swap if need be, however I would like to stay under and m130 since I am running modify 8mm ceramics. I never used an inner barrel this short and just wanted to know if I need to short stroke still or I don't have to since i assume a short inner barrel like this will cut fps.
     
  2. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

    8,166
    4,635
    Minneapolis
    First off. Have you shot it yet?

    With that short of a barrel and a M115 you should be already under 350fps.
     

  3. Ben3721

    Ben3721 Well-Known Member

    644
    325
    You literally are using the strongest bearings in the hobby.

    People use those in dsg builds pulling like m170 springs at like 55rps.

    Short stroking to match the barrel length vs using a ported cylinder has two different effects, a full stroke with a ported cylinder will have a higher fps with a lighter bb, but a short stroked setup on a full cylinder with a harder spring with that shorter barrel will have a slightly more positive joule creep with heavy bbs.


    If you short stroke, take 1 tooth off the release side and 1 off the pickup side, it's a timing thing, then cut the tappet fin at a angle half way down. Short stroking with a harder spring also helps with overspin and faster piston return time, where a full stroke ported cylinder will have the opposite effect.
     
  4. Big Chungus

    Big Chungus Member

    39
    2
    New York
    I am going to run an 80% cylinder and was planning on removing 2 teeth
     
  5. Big Chungus

    Big Chungus Member

    39
    2
    New York
    no I have not
     
  6. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

    8,166
    4,635
    Minneapolis
    Before you do any work...shoot it first.

    You need a base line otherwise you may do more damage...than good.
     
  7. Big Chungus

    Big Chungus Member

    39
    2
    New York
    I know that is usually what I do, just trying to save some time, in a pinch to get this build out.
     
  8. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

    8,166
    4,635
    Minneapolis
    In your situation, a chrono shot to determine your speed is faster than tearing down a mechbox to make mods that you may not need to do.

    You said you had a chrono, so why not check first before you even attempt to mod?
     
  9. Big Chungus

    Big Chungus Member

    39
    2
    New York
    I have built a good amount of ssgs and a few dsg but I have not built an aeg with this short of a barrel as I stated in the original comments. I am just trying to get tips on a spring idea to save me a few steps in tearing down and buttoning up the gearbox a few times that is all.
     
  10. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

    8,166
    4,635
    Minneapolis
    And I am saying (actually giving you a tip here)...you most likely won't need to do anything with your short barrel and M115 spring.

    The G&G ARP9 has a M120 spring and a 130mm barrel...it only hits 330fps.

    This is why I am saying...chrono first. Mod if necessary after chronoing...
     
    Last edited: Oct 8, 2021
  11. aotsukisho

    aotsukisho Well-Known Member

    770
    426
    Having a chrono and being hesitant to use it prior to beginning any sort of modification is terrible methodology, it should be the first thing you do after receiving any replica. Takes one minute to do, time is not an issue
     
    Guges Mk3 likes this.
  12. Big Chungus

    Big Chungus Member

    39
    2
    New York
    I chrono every build I complete and any replica that is not a box of parts before building and improving internal performance. To make it real simple, I wanted to see if anyone who had the same size inner barrel or near it just recommend a good spring to keep the fps at my desired goal. This is not a complete replica. Each aeg will perform different but just getting a general idea with an inner barrel this short with good compression and spring rating is all I was looking for.
     
  13. Big Chungus

    Big Chungus Member

    39
    2
    New York
    Yes, that is common sense. The information you stated about the arp9 inner barrel and spring is good and gives me a general idea
     
  14. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

    8,166
    4,635
    Minneapolis
    And you are misreading our comments.

    Tooth on the piston, not relevant.
    Holed Cylinders, not relevant.
    Motor type, Perfect compression, 13:1, bushings...also not relevant.

    Here is a simple question.

    What is the AEG with the M115 Spring and 155mm 6.03 inner barrel shooting .20g bbs at right now?

    Now if you are asking how can you keep an AEG that shoots .20g at 350fps or less with a 155mm barrel. We can honestly say, you don't need to do much. You won't exceed 350fps very often with a 155mm barrel with most standard use springs - M100 to M120 on a full cylinder.
     
  15. Big Chungus

    Big Chungus Member

    39
    2
    New York
    I'm sorry you seem to be getting frustrated, I do not know how to be more clear. Unfortunately you are still miss understanding what I am asking. The parts I mention are in fact relevant and I stated as to why I mentioned them. Once again, the aeg IS NOT A COMPLETE BUILD, as the parts are in a box. The last part of your comment is what I was asking several times. I am using a ported cylinder, and see that you mention a full cylinder. If the cylinder is irrelevant than why did you state a full cylinder? I mention the bearings because whether they are the strongest on the market or not, I do not like running bearings with higher than m120 springs. Most aegs come from the factory with bad compression. Ported cylinders do affect fps
     
    Last edited: Oct 8, 2021
  16. Big Chungus

    Big Chungus Member

    39
    2
    New York
    Tooth off the piston, saves weight, miniscule but weight is weight
     
  17. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

    8,166
    4,635
    Minneapolis
    Ah, by your last comment here, it is showing your level of understanding about mechbox builds.

    AEG's are whole systems. Not snap together Video gun builds where part A gives performance level 30.

    That is why I say, motor has no bearing on FPS, neither does the gears or battery type. They have no direct link to the actual pressure wave generated by the spring via the piston and out the nozzle to hit the bb. Thus...irrelevant.

    I cite the full cylinder due to one factor. It's the maximum level of Air pressure an AEG can generate. Thus if you put in a holed cylinder, it generates less Air pressure. Less Air pressure means less FPS. So...your top end fps "with" a short barrel is irrelevant on the cylinder type for a Max FPS reference.

    Again...I cite the G&G ARP9. Full Cylinder, 130mm barrel, high speed gears, M120 spring...top fps, 330 with .20g Your 155mm and M115 falls near or below this performance level....

    One thing that you did add above that was not originally detailed is, your AEG is not fully built yet. Most of us surmised you already had a functioning AEG, even though you said "CQB Build in progess". We thought you were modding a functioning AEG already

    Thus if you put the M115 in the listed build...you will be under 350fps.
     
  18. Big Chungus

    Big Chungus Member

    39
    2
    New York
    I understand the gearbox, different versions, as well as parts and performance. Building similar builds each time is one thing, and using a different component can change the dynamic of a build, undermining some one is quite rude and childish, but if it makes you feel better, than good for you.

    Most people do not grasp that changing 1 part will boost the performance to "level 30" as you state above.

    Following that ridiculous comment, The motor has absolutely NOTHING to to with FPS, nor the gears or battery type, as I never stated it did, but in fact stated the motor I was using to avoid generic comments such as "PME" and for people to understand the different components I am using. You assumed I believe it did. Ported cylinder does relieve pressure, as I have tested in a different build, same spring by 10-12 fps in that scenario. You do not just throw parts together and they work. High speed gears, higher torque motor, Higher torque gears such as 18:1 and so on, higher speed motor, that is my concept. Thanks for the responses.
     
  19. aotsukisho

    aotsukisho Well-Known Member

    770
    426
    Unfortunately we made assumptions it was a functional AEG due to you claiming to have "perfect airseal", which is impossible if the components are all in a box.

    For what it's worth, the G&G ARP9 comes with a 6.08x128mm inner barrel, using a 3/4 ported cylinder and what is apparently an M125 spring for ~330fps out of the box. Extending the barrel to 6.02x409mm gives 420fps as I have empirically measured in the past which is right around 128m/s, the variance is likely due to production tolerance combined with the fact that G&G has a bearing on both the spring guide and piston (overcompression).

    My current G&G ARP9 build uses a Prometheus MS135, 3/4 ported cylinder, 6.08x200mm inner barrel, and Siegetek gear set short stroked one tooth on release side. It averages 373fps with 0.25g (1.62J, ~417fps with 0.20g).

    Matching 3/4 cylinder volume should require a ~315mm long inner barrel for 0.20g. I don't think the relationship is linear, but two data points are here for you to use
     
  20. Big Chungus

    Big Chungus Member

    39
    2
    New York
    Hey no problem at all, just meant with a perfect air seal, as I see how I originally worded it. Just wanted a ballpark of what numbers could I possibly see. Awesome info, definitely helps. thank you!
     
    aotsukisho likes this.