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Thread: Bullpup linkage fix

  1. #1
    Chief Administrator 7.62x39's Avatar
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    Default Bullpup linkage fix

    This is a condensed version of this thread here http://www.gunco.net/forums/f43/aku-94-project-69073/ which is still open for posting.


    I picked up this AKU-94 kit second hand probably 5 or 6 years ago and never got around to it. The guy I bought it from had painted it coyote gray, but got no further.
    I'm using a very nice, almost new condition Romy G kit for this build.
    The biggest complaint about these conversions was the spongy trigger due to the long trigger wire.
    That is what intrigues me most about doing this build and why I bought the kit in the first place. I want to see if there is a way to correct that. I have no Idea how at this point, except maybe installing some sort of a bell crank system to shorten and maybe take some of the bends out of the trigger wire.

    I'm going to build it on one of copes new polish blanks, that I have already heat treated. That is the other thing that intrigues me about this build. I'm anxious to do a build on one of these receivers.

    Here is what I'm starting with.
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    Last edited by 7.62x39; 12-03-2012 at 07:34 PM.
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  2. #2
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    It should look something like this when it's finished.
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    I got the TG riveted in place, mag spacing set and front trunnion holes drilled.
    So far I'm loving these Copes blanks. Everything has been right on the money.
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    Last edited by 7.62x39; 12-02-2012 at 01:12 PM.
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  4. #4
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    After mocking this up and playing with it a little bit, I don't think the trigger is quite as horrible as the reports I've read. Don't get me wrong, it sucks, but not as bad as I was expecting.

    The front section is a pretty straight shot, not much room for improvement here.

    The second and third shots show the problem area, the 90 degree dog leg just ahead of the hammer release (I'm going to call it a sear) it flexes too much here.
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    Last edited by 7.62x39; 12-02-2012 at 01:32 PM.
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  5. #5
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    I got the top rails trimmed. Got the lower rails welded in and trimmed for mag clearance. The ejector is trimmed and awaiting heat treating.
    I'm not going to rivet in the rear trunnion or CS until I'm done playing with the trigger.

    I hated the big, blocky look of the TG so I knocked off the front of it and rounded all the edges.
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  6. #6
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    One of the guys who works for me is big into RC stuff. He's got cars, boats, planes, monster trucks even a helicopter. I have been bugging him to bring me in some of his spare linkage pieces. He finally shows up with 3 plastic bins full of the stuff. I poked through it and came up with a bunch of pieces I thought I might be able to use. I finally settled on this combination of parts.
    The brass pieces get silver soldered on to the SS control wire. This set up will make it adjustable on both ends. This will be far superior to the simple bent hooks that the factory linkage uses.

    I also moved the attachment point behind the pivot pin and raised it .150 to get a little more leverage. With the attachment in the stock forward position, you are limited to how high you can go since it is so close to the hammer pivot pin which the linkage must go under.
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    Last edited by 7.62x39; 12-02-2012 at 01:31 PM.
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  7. #7
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    This Norinco double hook that sniper69 graciously donated (thanks Mike) will become the new hammer release. Next it gets the arm welded on, the trigger cut off and the hole opened up for the Tapco sleeve and disconnector.
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  8. #8
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    1st pic. is finished "sear" made from a norinco double hook trigger.

    2nd pic. with linkage attached

    3rd pic. test of concept.
    Back when I was helping out Ace arms with some R&D, they used to send me all kinds of stuff. Once they sent me a whole box of reject blanks. Some were just cosmetic blems that were still usable blanks, while others were just trash that I used for various experiments.
    This was a piece of junk that I cut the side down on. It gives me much easier access for playing around with the linkage.
    Trying this stuff out in a regular receiver is kinda like trying to build a ship in a bottle.

    Back half is finished, now on to the front.
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    Last edited by 7.62x39; 12-02-2012 at 01:16 PM.
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  9. #9
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    This area is the achilles heel of the whole factory linkage.

    The new linkage requires a much "friendlier" bend, that in conjunction with increasing the wire diameter from the original .054 to .068 should remove all the "springiness" from the linkage. The threaded connection vs the original hook will eliminate the slop and reduce the take up.
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  10. #10
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    Finished.

    Although the trigger pull is slightly higher than I had hoped for (@8lb) it is very crisp with no signs of slop or sponginess. It feels like a normal AK trigger.
    All in all I am very happy with the results.
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