Fostech echo trigger

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    J

    jcutonilli

    Ultimate Member
    Mar 28, 2013
    2,474
    TinCuda said:
    OK, I re-watched the video and I will eat my hat if the bolt carrier is anything but a standard auto bolt carrier.

    The .22 converstion bolt does not travel back far enough to interact with the "sear/lever/trip" that the echo trigger uses to prevent the hammer follow.




    I do not own a 9mm AR rifle but, I would think that if you do not need a special fire control group to make the 9mm upper work, the echo trigger would work fine. That is as long as you use an auto 9mm bolt carrier.


    .,
    Click to expand...

    I suspect you will need to eat your hat.

    The bottom of the Fostech bolt is visible at the end of Tim's videos (MAC). It clearly shows a chamfer at the location where it would contact an auto sear. The Fostech part is different from a conventional auto sear in that it has a tail/extra material. (see your picture above) I suspect that this chamfer and tail prevent a standard auto bolt carrier group from fully seating and operating properly. It is unclear if there are other differences, but the presence of this chamfer makes the Fostech bolt proprietary.
     
    TinCuda

    TinCuda

    Sky Captain
    Apr 26, 2016
    1,558
    Texas
    jcutonilli said:
    I suspect you will need to eat your hat.

    The bottom of the Fostech bolt is visible at the end of Tim's videos (MAC). It clearly shows a chamfer at the location where it would contact an auto sear. The Fostech part is different from a conventional auto sear in that it has a tail/extra material. (see your picture above) I suspect that this chamfer and tail prevent a standard auto bolt carrier group from fully seating and operating properly. It is unclear if there are other differences, but the presence of this chamfer makes the Fostech bolt proprietary.
    Click to expand...

    OK, I watched the video again, this time to the very end. My hat did not taste all that bad. I can always use a little more fiber in my diet anyway. LOL

    By the way, at this rate, I may be running out of hats soon. After a little bit of research, looks like you have to be kind of particular about the hammer you use with a 9mm bolt carrier too.


    .,
     
    TinCuda

    TinCuda

    Sky Captain
    Apr 26, 2016
    1,558
    Texas
    I have been thinking a lot about this bolt carrier thing. One, because I was wrong, but mostly because they chose to use an altered bolt carrier rather than make their system work with otherwise stock parts. It seems it would be better to make the "trip switch" work with a standard bolt carrier. The metal removed seems very minor. I would think people would still gladly pay the 400ish bucks for the trigger and Fostech could add the cost of the bolt carrier to their profits. So, why then, do it? Do you think it was a reliability afterthought? I do not remember any mention of a "special" bolt carrier in any of the pre-release videos.


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    B

    Boss94

    Ultimate Member
    Feb 15, 2013
    6,945
    Possibly to apease atf in using a non full auto part ?? It also could be to make it harder for someone to copy the design. Only they know for now.
     
    clandestine

    clandestine

    AR-15 Savant
    Oct 13, 2008
    37,031
    Elkton, MD
    I would bet that it wouldn't pass the ATF mustard if it tripped the sear in the same spot, thus the custom carrier. I bet it has to be slightly longer or shorter than a M16 carrier trip.
     
    T

    Tihsho

    Secret Asian Man
    Aug 23, 2011
    764
    Frederick & HoCo, MD
    Is the other product that Tim is referring to the Franklin Armory Binary Trigger? If so I'll have to do some more research as I was looking into one of those. The anti bolt ride is a nice feature.
     
    TinCuda

    TinCuda

    Sky Captain
    Apr 26, 2016
    1,558
    Texas
    Tihsho said:
    Is the other product that Tim is referring to the Franklin Armory Binary Trigger? If so I'll have to do some more research as I was looking into one of those. The anti bolt ride is a nice feature.
    Click to expand...

    I have the Franklin Binary trigger. Mine is the one with the fire control group comes as a drop-in pack. This was the Gen II. It does not look like you can buy them from Franklin any more. They do sell the Gen III version now. Just FYI, the GEN I was only available as a complete lower receiver and if I recall was very expensive. Not to say the trigger alone is cheap. LOL

    The GEN II has a hammer catch that was suppose to be a "safety" feature to keep the hammer from going full auto. This is called a BUD. The acronym escapes me at the moment. This will cause a little quirky operation. If you pull the trigger with the bolt locked back (like if you are doing a mag dump and pull the trigger after your magazine is empty with the bolt locked back) you will release one of the sears but the BUD will hang onto the hammer. When you put a fresh magazine in. The next time you pull the trigger, all you will do is release the hammer from the BUD and you will not get a fire. Then, when you release the trigger, the rifle will fire. This is not a huge problem but it could startle you if you are not expecting it to work that way.

    Also one thing to note on the Franklin Binary, when using a .22 conversion, the .22 bolt is cut in a way to cause the hammer to engage the BUD every time. This makes the system a Release Fire Only trigger. To get a .22 bolt to work, you have to machine the bolt bottom so it does not push the hammer as far down and not engage the BUD. Again, this is only on the GEN II system.

    The Gen III comes as individual pieces of the fire control group and I believe it uses a standard semi hammer. The BUD is not part of it's design. This might be the best Franklin trigger. I may get one in the future to see what it is like.

    If I get one of the Fostech Echo triggers, I will write up a comprehensive review and comparison of them all. It will just take a little time for me to get them all together, but I will likely do it.


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    J

    jcutonilli

    Ultimate Member
    Mar 28, 2013
    2,474
    elshek said:
    reminds me of the tac con trigger
    Click to expand...

    No, the tac con trigger is more similar, but not exactly like a bump fire stock in that it assists moving your trigger finger forward. Hammer release is still only on the pull.

    The fostech has a mode where it releases the hammer on a pull and again on a release. it is similar to the franklin arms binary trigger. The biggest difference between these is that the fostech has an auto sear like feature that prevents hammer follow if fired too fast.
     
    S

    sniiped

    Member
    Dec 28, 2015
    3
    I have one of these on preorder. I'm going to see what I can do to modify the hammer disconnect at the back of the trigger so a normal full auto carrier will work with it. I'm not too hip on modifying my carriers for the trigger. I will modify the trigger for my carriers.

    I did see an IV8888 video today and they modified a 9mm bolt to work with the echo trigger. I'm going to really see what I can do with this trigger. I have a pistol project it's going into and I have several uppers for this lower. Once finished, as long as everything goes according to plan, I should have quite the little truck gun. I'm pretty excited to see how it pans out.
     
    GeorgeSSR

    GeorgeSSR

    Active Member
    Jan 31, 2009
    196
    clandestine said:
    I would bet that it wouldn't pass the ATF mustard if it tripped the sear in the same spot, thus the custom carrier. I bet it has to be slightly longer or shorter than a M16 carrier trip.
    Click to expand...

    Looking at that video, it looks like that lever is separate and can be replaced...
     
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