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Full Auto Only :/

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  • 20-06-2011 2:00pm
    #1
    ronan keane
    Registered Users Posts: 1,414 ✭✭✭


    Hey Guys my SRC M4 is shooting Full Auto Only whats the cause?


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    #2
    Private Snafu
    Registered Users Posts: 1,815 ✭✭✭Private Snafu


    Could be a multitude of things really. Start off by checking your cutoff lever.


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    #3
    bullets
    Registered Users Posts: 4,612 ✭✭✭bullets


    Theres something called the cut off lever which may be too tight and may
    cause the gun not to fire in semi.

    The cut off lever also has a tiny little return spring on it which might have come loose or popped off.

    The plastic selector plate which moved back and fourth when you change from semi to full could also be damaged
    or worn.

    ~B
    EDIT I had this snippet of info copied and pasted from another website which explains a little about the
    cut off lever. (Cant remember where I robbed the info from though)


    Cut off lever:
    . On an m4 V2 you will notice with the selector plate on safe the little portion of the cutoff lever actually sticks out of part of the GB in a slot in the selector plate and there is a spring between it and the selector plate. As you move the selector plate to semi you disengage the mechanical and electrical safeties and the cutoff lever remains in the selector plate notch untouched. When you fire the sector gear rotates until it pushes the cutoff lever up, against the spring, and then the spring returns it to its reset downward position for the next shot. Then you push the selector plate to full auto. You will notice when you do this it pushes up the cutoff lever, which is curious. Why would moving the selector plate to full auto push the cutoff lever up into the cutoff position where it lifts the trigger block off of the trigger sear allowing it to return backwards and cut off power?

    This occurs because there is a small nub on the side of the trigger block which engages the cutoff lever to lift the block and move it off the trigger sear. This allows the trigger block spring to pull it backwards and disengage the contacts. HOWEVER the arm of the cutoff lever MUST start below that nub on the block. If the trigger is pulled with the arm of the cutoff lever above the nub on the side of the trigger block it is above it, obviously, and therefore can't lift it and can't cut off power. This gives you full auto in most AEGs.


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    #4
    ronan keane
    Registered Users Posts: 1,414 ✭✭✭ronan keane


    bullets wrote: »
    Theres something called the cut off lever which may be too tight and may
    cause the gun not to fire in semi.

    The cut off lever also has a tiny little return spring on it which might have come loose or popped off.

    The plastic selector plate which moved back and fourth when you change from semi to full could also be damaged
    or worn.

    ~B

    Here is a picture of the Selector Plate
    S77hr.jpg


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    #5
    bullets
    Registered Users Posts: 4,612 ✭✭✭bullets


    ronan keane wrote: »
    The anti-reversal Latch?

    No thats different. the Anti-reversal latch makes sure your gears will turn in
    once direction like a ratchet . :)

    ~B


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    #6
    Private Snafu
    Registered Users Posts: 1,815 ✭✭✭Private Snafu


    No, the AR latch stops the gears from turning backwards. It has zeo effect on the fire select setting.


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    #7
    ronan keane
    Registered Users Posts: 1,414 ✭✭✭ronan keane


    Does my Selector Switch look ok?


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    #8
    bullets
    Registered Users Posts: 4,612 ✭✭✭bullets


    Cant tell from the pic if the bit that interacts with the fire selector switch is ok or not. I know on one of my guns I damaged this bit and it fires on auto only
    as when I turn the switch the selector plate wont change positions.

    You could try moving this manually to both the semi and the full auto positions and then try and fire the gun. (if you've the motor attached to the gear box or in the lower receiver or pistol grip ) If it works on semi by moving this you know your the cut off lever mentioned earlier is probably working ok and the issue may be to the selector plate or around your selector switch. (Not sure if I am making sense or not)

    I'm not too well up on the techy side of things as only took a gear box
    apart 2-3 times.

    ~B


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    #9
    ronan keane
    Registered Users Posts: 1,414 ✭✭✭ronan keane


    bullets wrote: »
    Cant tell from the pic if the bit that interacts with the fire selector switch is ok or not. I know on one of my guns I damaged this bit and it fires on auto only
    as when I turn the switch the selector plate wont change positions.

    You could try moving this manually to both the semi and the full auto positions and then try and fire the gun. (if you've the motor attached to the gear box or in the lower receiver or pistol grip ) If it works on semi by moving this you know your the cut off lever mentioned earlier is probably working ok and the issue may be to the selector plate or around your selector switch. (Not sure if I am making sense or not)

    I'm not too well up on the techy side of things as only took a gear box
    apart 2-3 times.

    ~B

    On second thought i'll just bring it to a techie


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    #10
    bullets
    Registered Users Posts: 4,612 ✭✭✭bullets


    You've the thing almost open now! be brave and do a bit of poking about
    and figure out what does what :D:D:D ya know ya want to really! whats the worst that could happen :)

    ~B


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    #11
    ronan keane
    Registered Users Posts: 1,414 ✭✭✭ronan keane


    bullets wrote: »
    You've the thing almost open now! be brave and do a bit of poking about
    and figure out what does what :D:D:D ya know ya want to really! whats the worst that could happen :)

    ~B
    That I break/Lose stuff and I have to pay even more :P and I took it apart that much to put in a hop-up rubber (Src made a weird way of getting to the Barrel)


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    #12
    DeBurca
    Registered Users Posts: 9,746 ✭✭✭DeBurca


    There is probally some wear on the moving trigger contact lobe (see photo)which makes contact with the cut off lever
    Due to the wear it is no longer being tripped at the end a single cycle and the moving contact remains in engaged with the fixed part of the switch causing the AEG to fire full auto

    [img][/img]switchq.jpg
    Uploaded with ImageShack.us


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    #13
    RABBIT.
    Registered Users Posts: 47 ✭RABBIT.


    this has been sorted for ronan, happy shooting my friend


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