3D Printed Conversion for Thompson SMG to take M4 Magazines

Discussion in 'Gun Building, Modifications & Repairs' started by catkaze, Jan 10, 2019.

  1. Hell yeah! Screw realism!

    90.0%
  2. This design (and you) should be purged from existence.

    10.0%
  1. catkaze

    catkaze Active Member

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    Hello everyone!
    I recently acquired a boneyard Thompson SMG on the cheap to fix up and realized something. Due to the way the magazine is inserted into the gun, it would be a relatively simple task to create a magazine conversion kit to allow M4 magazines to be used. As soon as I thought of this abomination, I knew I had to create it. Since I own my own 3D printer, I can actually produce this. I have printed a low-resolution low-infill prototype to test the fit of my rough mock-up, and it almost worked. I have since revised the design and ordered more filament. I will attach photos of the finished result once I have it printed successfully. The reason I am posting this thread is because I wanted to see what the airsofting community thinks of this unforgivable sin.

    [​IMG]

    Disclaimer: If you couldn't tell by the tone of the above post, I am fully aware there is no way a conversion kit like this would work in real life. There is no way a 5.56 round could ever feed into a .45 caliber SMG. That being said, I still fully intend on using this at some point, as m4 mags are a fair degree cheaper and more readily available for purchase.
     
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  2. fred_ditto

    fred_ditto Well-Known Member

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    Sounds like a legit plan. Excited to see what happens!
     
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  3. C.M.G

    C.M.G New Member

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    Disgusting heresy.


    Me likey. Dew it
     
  4. Topshotz357

    Topshotz357 Well-Known Member

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    I need a picture of the finished product so the Tommy gun with the m4 mag in it in order to make my decision
     
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  5. adas1223

    adas1223 Well-Known Member

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    Thompson_M1A1_Metal_AEG_CG71015_zm01__10932.1447867335.1280.1280.jpg
     
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  6. fred_ditto

    fred_ditto Well-Known Member

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    Better than a P90 with adapter. Might have to get a Thompson just for V6 gearbox+ M4 mags.
     
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  7. adas1223

    adas1223 Well-Known Member

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    im staring at it now, and theres been talk about Wood on an m4 in the discord DIY airsoft server.. this is pretty much it lol

    if you went this far, paint those m4 mags "ak bakelite orange" and confuse that crap out of everyone
     
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  8. Topshotz357

    Topshotz357 Well-Known Member

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  9. catkaze

    catkaze Active Member

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    I will. I am currently in a college dorm, so no airsoft guns allowed here, but I am heading home for the weekend after my class today. I'll start printing a low-density test print using my remaining white filament today. My black filament arrives tomorrow, so that's when I will print the final draft (assuming the test print fits). In short, I should have picture of the result by the end of the weekend.

    If you want one on the cheap, you can get one for under $100.00 from here: https://airsoftmarketplace.com/airsoft_boneyard.php?page=7

    They are boneyard, but out of the 4+ guns I have bought from this boneyard, the issue was almost always a blown fuse. The only exception was a serious bb jam that required the hop-up and inner barrel be pulled away from the gearbox to be cleared. This is where I got my Thompson, and it only cost me about $60.00 ($10 of which were used to buy screws to mount the loose stock, wires to extend the wiring harness to the back of the stock, and mini tamiya connectors to solder to the extended wiring harness).
     
    Last edited: Jan 11, 2019
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  10. -Spitfire-

    -Spitfire- Well-Known Member Supporting Member

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    It's not technically an airsoft gun if it's not complete, assembled, and functional.... Coming from experience.
     
    Last edited: Jan 11, 2019
  11. fred_ditto

    fred_ditto Well-Known Member

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    Thanks!
    But momma, that's where the fun is...
     
  12. catkaze

    catkaze Active Member

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    IMG_5232.jpg View attachment 157947
    Here are a couple of photos with the initial test adapter that I printed. The latest revision is on the printer now.
     
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  13. fred_ditto

    fred_ditto Well-Known Member

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    Looks good. How much are you thinking of charging?
     
  14. catkaze

    catkaze Active Member

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    I'm thinking something like $20 + shipping for a complete set (fully assembled). That would include the 3D printed adapter, the spring for the mag release, and the pin for the mag release. Would anyone be interested in buying a kit?
     
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  15. fred_ditto

    fred_ditto Well-Known Member

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    Me. And I don't even have a thompson.
     
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  16. catkaze

    catkaze Active Member

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    Ok. I will post a thread in the classifieds section when I have the final design down and am ready for a production run. Until then, I'll be posting updates on this thread. I'm not sure how long it will take, but I want the final result to look and function perfectly. I won't sell them until I can be sure that they work consistently.
     
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  17. catkaze

    catkaze Active Member

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    I have now completed the design and am ready for production. I'll attach photos to this post. IMG_5263.jpg IMG_5264.jpg IMG_5265.jpg IMG_5266.jpg IMG_5267.jpg IMG_5268.jpg IMG_5269.jpg IMG_5272.jpg
     
  18. Automobilie

    Automobilie Active Member

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    Looks great!

    I'll bet you could flare out the top to match flush with the upper and set up some kind of fastening system totake the old mag catch off.
    I might have a build that needs this...

    [​IMG]
     
    HopRanger likes this.
  19. catkaze

    catkaze Active Member

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    Thanks! That is certainly a beautiful gun! I have made some design adjustments so that the final result is sturdier. I also added my logo to the right-hand side of it. I'll post pictures when I print my next version.