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Thread: 9mm AK my way

  1. #21
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    Quote Originally Posted by kernelkrink View Post
    Both the G3/CETME designs and this 9mm build are blowback operated, there is no gas piston that enters a gas block and no gas port.
    [slaps forehead] Of course! Now it all makes sense. Somehow I overlooked the blowback part.

    Looks like I'll have to figure out something different.

  2. #22
    GuncoHolic kernelkrink's Avatar
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    If I were making a standard AK with a non reciprocating handle I would make a sleeve that slides over the tube. Attach a handle similar to the G3 so that when unfolded it reaches inside the tube but folded forward it exits the tube. Right behind the gas piston head add a full diameter ring for the lever to act against. Locking stud on the gas block similar to the G3 to retain handle in forward position.

    Looking at pics of the INSAS it loooks like they use the external sliding tube, but with a fixed handle? They also use a one piece gasblock/FSB placed way out towards the end of the rifle, the gas piston is longer than a standard AK. With a gas piston ring to interface with the cocking handle it wouldn't need to have a retractable lever to engage it, the travel of the piston wouldn't be enough for the piston head to hit it in recoil if it's spaced right. Stripping is probably accomplished by manually retracting the stud on the cocking handle that engages the piston.

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    Happy Camper hcpookie's Avatar
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    Personally not a fan of that left-side gizmo. I understand the why, just not my cup of tea.

    The S.A. CR-21 uses a non-reciprocating charging handle for its bullpup configuration. It engages a tab welded onto the bolt carrier. This is the best non-reciprocating charging handle idea I've seen.

    Look here, you can see in some of the pics the charging handle, the tab, and the way they are both mounted in the rifle:

    http://pookieweb.dyndns.org:61129/CR21/CR21.htm

  4. #24
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    hcpookie:
    You have to have a RSB with a hole in it for the pushrod to slide through. Notice the CR21 has a hole on each side (rld2.jpg) so the pushrod can go on either side. You also have to modify the top cover with a slot and probably some kind of cover for the welded-on tab to ride through. The pushrod guide tube would have to be attached to the outside of the gas tube up front. I might do this with another build, but I really want the Valmet look for this one.

    kernelkrink:
    I pulled the upper handguard and top cover off my AKM and did some measuring. The length of the gas tube from the gas block to a conventional RSB is 6.5 inches. The stroke of the bolt carrier until it hits the spring retainer is 4 inches, leaving 2.5 inches of the gas piston sticking out the front of the RSB.

    possibility 1:
    If you made a new gas piston with a longer head, you could screw a knob into the extended area behind the head, cut a slot in the gas tube, and screw a cocking handle directly to the gas piston. Unfortunately the handle would have to be removed to get the bolt carrier out.

    possibility 2:
    You could use a non-fluted gas tube and a floating sleeve inside, the ID of the sleeve allowing the head of the gas piston to slide inside. Put a tab on the sleeve and attach the cocking handle to it. If the handle is at the front, cut the slot all the way to the end of the gas tube where it goes into the gas block. The sleeve would engage the bolt carrier at the back.

    To disassemble, remove the bolt carrier, then remove the gas tube - the sleeve should be shorter than the tube - and slide the inner sleeve out from the front.

    Hmm, that might work. And my Galil gas tube is larger inside than (the fluted section) of a regular gas tube; there might be room for an operating tube sliding in there...

    gas piston OD: .545
    Galil tube ID: .685

    ... and WTF? The Galil tube ID and OD vary .010 down its length. So much for keen Israeli quality control. Well, it *is* an AK, after all...

    The closest standard inch tube is 11/16, nominally .687. A 16 gauge tube has a nominal wall of .063, so the theoretical ID is .561. Remove a little off the OD of an 11/16 tube until it slides freely in the gas tube, and you're in business!

  5. #25
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    Okay, I'm coming up with zip searching for some 11/16 x 16ga or 18ga tubing. As usual, it seems to be one of those sizes listed as "standard" that nobody actually carries.

    I could turn something larger down on the OD, but the ID can't be smaller than .550-ish. I don't want to try opening up an ID that deep.

    I wish I could find a chart that listed tubing by ID instead of OD; this isn't the first problem of that sort I've run into.

  6. #26
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    The interestings about Gunco are:

    A) when I say something about being stumped by something, someone points me to just what I was looking for.

    B) when I spend an hour explaining some elaborate Rube Goldberg method of doing something, someone points me to something much simpler.


    In this case, schedule 80 water pipe is theoretically .546 ID, and 3/4 OD by .083 or .095 wall tubing is .584 or .560 ID.

    "We now return you to your regular programming."

  7. #27
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    3/4 x .095 wall, DOM "seamless hydraulic tubing" was the best I could come up with locally. A two-foot piece was $17. (ouch!)

    I'll have to turn the OD on the lathe, but the ID should be perfect for an AK gas piston to slide through.

    Now I'm trying to figure out how to attach the block for the cocking handle. I've seen people attach crazy things like recoil lugs with silver solder or braze, but I've not had that kind of success. <sigh> It'll likely be one of my usual grotty MIG welds and some Dremel work to hide the horror.

  8. #28
    No Hope For Me Coils's Avatar
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    You starting to get confusing. Are you going to use a G3/CETME style cocker?
    If your going to do this style cocker, think it out a little simpler.
    You got a lathe. Can you cut threads?
    Since your making it blow back, make an AK piston but instead of having the piston head at the end move it back on the shaft, the OAL will be the same yet so the tip will go into the gas block. This bulge on the shaft is what the cocking handle will push against to push the bolt back to cock it and the handle will stay front while firing.
    The G3/CETME cocking handle is on a tube like thing, this will ride inside the gas tube (that you make) and the piston rod will move inside this tube thing on the cocking handle.
    If your not using the G3 handle, I just typed all this for nothing
    "Government is not the solution to our problem, government is the problem" Ronald Reagan

  9. #29
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    Quote Originally Posted by Coils View Post
    If your not using the G3 handle, I just typed all this for nothing
    Why should you be the only one? <grin>

    This is for my Beowulf build. I don't know if I'll be using a G3 handle; the bits are cheap enough I'll get some next time I order from Sarco or Numrich. If I like the look I'll use them, otherwise I'll fab something from scratch.

  10. #30
    No Hope For Me Coils's Avatar
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    Why should you be the only one?
    LOL

    This is for my Beowulf build.
    OH hell no wonder I was getting confused, I thought you were going to do this on a pistol caliber build.

    If the Saiga 223 were cheaper, that would be a good candidate for the caliber.
    "Government is not the solution to our problem, government is the problem" Ronald Reagan

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