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Thread: Mac jack

  1. #1
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    Mac jack

    I came across a cool looking device called the Mac jack but it appears itís
    Only for the M11? Is there one for the M10 and if not is there a reason why
    Something like this will not work with it?

  2. #2
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    The M11/NINE has some room behind the point at which the sear will catch the bolt. That extra room is where the Mac Jack is placed. There are a couple of ways to effect cyclic rate in an open bolt submachinegun, change the mass of the bolt or change the length of the stroke of the bolt. The Mac Jack shortened the length of the stroke to just beyond the point at which the sear can catch the bolt.

    The M10 stroke is pretty much at the point just beyond where the sear can catch the bolt. So the M10 doesn't have the extra stroke length that the M11/NINE has. So the M10 doesn't have the additional stroke length where a Mac Jack device would be placed. The stroke length of the M10 is why the TASK style conversion does make as much of an impact for the M10 as the M11/NINE. The M10 doesn't have the length of stroke the M11/NINE has. To increase the stroke of the M10 either the lower receiver would need to be lengthened, or the bolt would need to be shortened. The problem with shortening the bolt is the ejector would fall out of the bolt. I hope this answers your question.

    Scott

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    Good to know, learned something new today thank you both!

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    Awesome! Thank you for the response Scott.

  5. #5
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    What the M10 lacks in stroke, it makes up for in girth.
    Last edited by Gaujo; 04-05-2021 at 11:31 AM.

  6. #6
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    Quote Originally Posted by Gaujo View Post
    What the M10 lacks in stroke, it makes up for in girth.
    Yes and no in my opinion. Certainly the M10 factory 9mm bolt has more mass than the M11/NINE factory bolt. So in factory configuration the M10 9mm is the slowest cyclic rate. The whole point of the TASK system is to add mass to the bolt to slow the cyclic rate. I am fortunate enough to have a TASK modified M11/NINE and M10 receivers. Because of the additional stroke, the M11/NINE is much easier to slow to pull singles. With the M10, I have added so much mass that the gun would short stroke. Icutbackjustoneounce. I still found it difficult to pull singles. It was too easy to pull the trigger far enough to release the bolt. But I could not let go of the trigger quickly enough to catch the bolt, so I get doubles. It was suggested to me to add a screw to the trigger to limit over travel. Since I am using my M10s with Tenko testing, I really don't want to limit trigger travel.

    Something that I have in the back of my mind is to cut down one of my spare TASK modified bolts and cut it close to the spring in the extractor. Then drill out the hole for the ejector to have a sleeve the would support the ejector. I would make the sleeve spring loaded so that the sleeve would collapse inside the bolt when the bolt goes to the back of the receiver. Maybe the extra throw will help me to pull singles easier.

    Scott

  7. #7
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    gaujo, i see what you did there.

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