E&L AK Build (My Worst Idea This Year...)

Discussion in 'Gun Building, Modifications & Repairs' started by Cothonian, Mar 31, 2020.

  1. adas1223

    adas1223 Well-Known Member

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    goodluck! one of the reasons i really want to try the optical mosfets. no more trolleys and cut off levers lol
     
  2. Lefse

    Lefse Well-Known Member Supporting Member

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    Trolleys and cut-off levers are your friends. :D
    Friends that some times act like assholes, but they try dammit.
     
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  3. Guges Mk3

    Guges Mk3 Well-Known Member Staff Member Supporting Member Lifetime Supporter

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    Why are you swapping SHS gears with E&L gears again?

    You know they are on par with each other and the SHS in this case is not really and "upgrade".
     
  4. Cothonian

    Cothonian Member

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    Build ultimately came out as follows:
    GATE Titan
    SHS High Speed Gearset
    Shim job
    G&G Green Bucking

    Literally everything else stock. Trigger response is wildly impressive (this is without pre-cocking) to the point that some people thought I was firing full auto when I was in semi.

    The only hiccup (because there HAS to be one...) is that FPS is only at 345 with .2s. Currently, the gun has its stock spring (roughly M120 equivalent) which should be pulling higher than that, closer to 375 at least.

    Definitely no leaks at the hop up unit. Before re-assembling the gun I made sure to check the cylinder and nozzle compression, both of which were good at the time. FPS is pretty consistent (only a 2 to 3 foot deviation) so I'm wondering if maybe the spring was soft from the factory. The one mistake I made was never chronoing the gun prior to modifying it.

    For now though, it definitely works for field use. Eventually, I'll be taking it apart again to test for any compression issues. Assuming there are none, I'll definitely be upgrading the spring. 380 FPS is the sweet spot for me.

    In the mean time though, it's just nice to enjoy a custom gun that works. It's truly a rarity for me.
     
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  5. Guges Mk3

    Guges Mk3 Well-Known Member Staff Member Supporting Member Lifetime Supporter

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    Nozzle compression between cylinder head and nozzle is a false check.

    Fluid Dynamics shows that if there is no seal between tube and nozzle, it is not an issue if the gap is minor. By minor that means 1mm or less. Yes...that big.
     
  6. Cothonian

    Cothonian Member

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    After a lot of messing around, FPS issue is still present.

    For a brief period of time, the FPS dropped to 300 with .2s. I've since removed the delayer chip and the FPS is back up to 340. Feeding still works fine. This could indicate that the nozzle movement is not synchronized with the piston, though I'm hard pressed to confirm this since I'm not feeling any air come out of the feed tube.

    Changed out the spring with a Krytac stock spring which should give me 375 FPS. FPS still sits at 340 though.

    Barrel is stock E&L.

    As always, can't find any leaks. Not really sure where things could be getting bound up though.

    To quote another thread on this forum, "resist the urge to just upgrade the spring," so I am trying to focus down the source of the FPS loss. I'm just out of ideas.

    Might still upgrade the spring though... the gun cycles so fast that it "double shoots" in semi. I think a tougher spring would negate that problem.
     
  7. Guges Mk3

    Guges Mk3 Well-Known Member Staff Member Supporting Member Lifetime Supporter

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    That sounds like a weak spring issue.

    Can you update/confirm the barrel length and cylinder type again.
     
  8. Cothonian

    Cothonian Member

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    16" barrel, stock E&L. (I've read that it's a tight bore, can't confirm.)

    Started looking at the cylinder, and dang, no ports. Cylinder + cylinder head are one piece.

    I'm surprised by this because my other E&L (stock, no modifications) shoots hotter and presumably has the same internals.

    I have another spare cylinder + cylinder head that is ported (port ends 1" from the end.) Guess I'll try installing that and see if it helps with FPS.

    Only issue that could remain is the double shooting in semi. I must admit, the stock E&L motor is quite strong.
     
  9. Guges Mk3

    Guges Mk3 Well-Known Member Staff Member Supporting Member Lifetime Supporter

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    16" is roughly a 400mm barrel. A Type 1 cylinder is appropriate for a barrel that long. Type 0 is not going to make the right pressure wave for a barrel of that length.

    A type 2 Cylinder will not help your FPS issue when you have a barrel that is so long. There isn't an internal taper to the no hole cylinder is there?

    Motor strength is only part of the factor...honestly a good known, new M120 may just solve your problems.
     
  10. Cothonian

    Cothonian Member

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    Just to confi
    Just to confirm:

    [​IMG]

    The top one is a type 2 and the bottom one is a type 1, correct?

    ...and a type 1 would be best suited for a ~400mm barrel?

    My spare cylinder head is currently mated with the top one and I can't get it out...
     
  11. Guges Mk3

    Guges Mk3 Well-Known Member Staff Member Supporting Member Lifetime Supporter

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    Yes, Type 1 is the lower one.

    Put a dowel in the cylinder and knock it out.
     
  12. Cothonian

    Cothonian Member

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    Lonex Type 1 cylinder installed.

    FPS still at 340.

    I think I'm about ready to give up on this project. There comes a point of diminishing returns.