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Thread: Standardized barrel threads (Autococker)

  1. #31
    Good catch. I screwed up converting, should be 0.94"

  2. #32
    I updated the drawings on my G-Drive to the dimensions that Simon just gave us.

    https://docs.google.com/folder/d/0B2...kd0c2RldjZoZ1E

    Filename is just "AC BARREL SPECS".

  3. #33
    Insider PBSteve's Avatar
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    Thanks for that, I didn't get around to it again that afternoon and won't have access to my CAD stuff for another week.

  4. #34
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    Well, I don't know what you guys are doing with your AC threads, but here's what I did:

    mag2cocker_sls.jpg

    It's basically Doc's Mag to Cocker adapter, but with some minor changes:

    1. Two detents, because having one break on you mid game really sucks.
    2. Plastic, obviously.
    3. Slots cut in the threaded section.

    Being made out of plastic, it's way cheaper and lighter, but it also has a bit of flex, which I use to my advantage. The slots cut in the (slightly undersized) threads allow the adapter to expand and press fit against the Automag body. This means I don't need the classic barrel o-rings to make the adapter snug and conform to slight variances in body size, and I don't need the twist-lock pin, which I think was a bad design which has knock-on effects to the grip frame.

    Field testing this weekend. I have some more tweaks I want to make, but it looks like it's functional as-is.

    The best part is I didn't have to beg a machinist to do this for me. I just drew it up in Sketchup (and I didn't even draw the threads -- used an OpenSCAD library for that) and uploaded it to Shapeways. $17.

  5. #35
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    That looks great, what material is it? How are the tolerances?

  6. #36
    It's made by the SLS, Selective Laser Syntering, process. That means it's either a nylon or a glass filled nylon material similar to 30% glass filled nylon.

    Typical tolerances are around 5 thousands per inch, but you can end up better.

    It's a cool part.

  7. #37
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    Yes, it's some sort of nylon; the exact type I don't know. It fairly durable; not glass-filled-nylon-durable though.

    It fits perfectly inside both my mags. The XY tolerances are pretty good, but the coarsest dimension I think is the z-layer height, which is 0.1mm for Shapeways' SLS.

    I played with it this weekend and it worked perfectly fine.


  8. #38
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    Awesome, might try it with Nylon 6 on an extruder (with an O-ring around the bolt) at some point.

  9. #39
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    Since this thread went the way of the Dodo bird, I'll re-upload my files for you:

    https://docs.google.com/file/d/0B-bP...it?usp=sharing
    https://docs.google.com/file/d/0B-bP...it?usp=sharing
    https://docs.google.com/file/d/0B-bP...it?usp=sharing

    For the Evil Pipe Kit, the decals denote the wrong bore so Figure #1 lists the decal and then the measured bore.

  10. #40
    Insider PBSteve's Avatar
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    Anyone have the specs for good ol' WGP barrels/markers? If not I can try to pull something from my old prostock barrel... if I can find it.

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