The Thompson Submachine Gun

Discussion in 'General Gun Discussions' started by Brubz, May 7, 2021.

  1. SunnySlopes

    SunnySlopes Member

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    Mebbe my favorite scene in the movie "The Highwaymen" with Woody Harrelson was where Frank Hamer (Kevin Costner) goes into the neighborhood gun/fun store and starts buying machine guns, etc, off the rack. A Thompson was in the bunch. He got a drum mag and a bunch of stick mags too.

    I think our founding fathers fully intended for that to be the norm, viz. the citizenry owning the same guns as the govt. Else, how could we defend against jack boot thugs from the govt?
     
  2. jeff-10

    jeff-10 Member

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    No, I saw it on Facebook right before this post. You can Google "tommy gun furniture for AR" and find some for sale. Costs more than some AR's.
     
  3. Ironicaintit

    Ironicaintit Member

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    I got to play with one as a kid, and it was a hoot. L drums always seemed to work fine as long as you set the tension correctly... but if you lost that “3rd hand”, you were SOL.

    Mag changes with sticks is so much faster anyways
     
  4. CapnMac

    CapnMac Member

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    The Feebs still have one commissioned in .38super; the collectors seem to regard .38super Tommys as unicorns, and for good reason.
     
  5. jeff-10

    jeff-10 Member

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    What's even more odd, to me at least, is that as late as 1989 the FBI had 10mm Tommy Guns and knowing how the government works, I wouldn't doubt they are still stored somewhere. You would think buy the late 80's there were more practical choices than a 10 pound Chicago Piano.
     
  6. tark

    tark Member

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    Our bad. We were upwind of the thing. Didn't realize those suckers had such good noses.
     
  7. Speedo66

    Speedo66 Member

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    I find the incongruity of a guy in fuzzy chaps toting a sub machine gun hysterical. lol

    Reminds me of how amazed I was initially watching "The Wild Bunch" and seeing the mix of traditional western guns like SAA's, Sharp's rifles, and Winchester 92's and "modern" guns like 1911's, a Luger, Springfield '03 bolt actions, and even a 1917 Browning machine gun, although the movie was set in 1913.
     
  8. Ramone

    Ramone Member

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  9. Airborne Falcon

    Airborne Falcon Member

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    Little known fact.

    It was my former grandfather-in-law (ex-wife's grandfather) who invented/designed the Thompson for Colonel Thompson. His name was Theodore H Eickhoff.

    I actually got to shoot the 3rd one, commemorative #3, that Colonel Thompson gave to Grandpa Theodore who then passed it to his Son whom I knew as Uncle Teddy ... he actually worked for the CDC.

    Miriam, Theodore's daughter, was my mother-in-law and they were quite well-off ... she married a well-to-do Kussrow. They were staunch liberal Democrats which, after some years led to a divorce for my ex and I ... thank the Good Lord. Been married to my current and final wife for a couple of decades now ... odd how all of that worked-out.

    They were good people though. Miriam worshipped her Daddy though, still does. She's still alive. They all moved from Ohio down to North Carolina some years ago, decades ago, where they own a large estate in the mountains which is where I met my first wife.

    Their home is sort of a Shrine to Theodore Senior. He was quite an accomplished man.

    There is letter he wrote about the entire design and production of the Thompson somewhere around here ... lemme look.

    Yep, here we go ...

    http://www.mikesmachineguns.com/Eickhoff_p3.html
     
  10. Old Dog

    Old Dog Member

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    Absolutely one of the great movie scenes of all time -- plus he gets the Colt Monitor, a BAR, and didn't he grab a registered Magnum as well? Among others...
    Just for the younger folk who may not be familiar, Zevon's "Roland the Thompson Gunner"
     
    Last edited: May 11, 2021
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  11. Brubz

    Brubz Member

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    I understand the engineering principle of the stick magazine a spring forces a new round into the chamber vacated by the expulsion of the used round. So I assume that something similar is at work with the drum magazine but what causes the drum to rotate?
     
  12. Tommygunn

    Tommygunn Member

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    Wind up spring; there is a "key" or winder on the front of the magazine.
     
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  13. Brubz

    Brubz Member

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    Great stuff thanks for sharing that with us
     
  14. CapnMac

    CapnMac Member

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    As @TommyGun notes, a rotary guide powered y a spring.
    You open the front cover to load ammo, then click a number of clicks (typically stamped on the face of the drum) to tension the spring correctly.
    Video:
     
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  15. CapnMac

    CapnMac Member

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    The original tommy was meant to use the "Blish Principal" which was where dissimilar metals change adhesion/friction based on pressure.
    So there was a sliding block in the originals (in brass, IIRC) that was to stay "locked" until the pressure dropped to a certain level, then open.

    Turns out Blish applies mostly at naval rifle pressures, not handgun round pressures, and the tommy was just friction delayed blowback. This is also what allowed the M1 & M1A1 tommy to be so much simpler to build, they went to more of a delayed blowback design with far fewer parts and not needing as many precisely-milled surfaces.
     
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  16. AlexanderA
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    AlexanderA Member

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    There is an oft-repeated myth that British armorers, in the North African theater, discovered that the Thompson would run just as well without the Blish lock (indeed, better, because sand would not gum up the works), and so removed the Blish locks. Unfortunately, that story overlooks the fact that the Blish "H" piece is the link between the actuator and the bolt, and so is absolutely necessary for the functioning of the weapon. (The M1 / M1A1 Thompsons don't have a separate actuator; their bolt handle is plugged directly into the bolt.)
     
  17. Tommygunn

    Tommygunn Member

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    It is true that removing the Blish device (the army called it the "H" device because it does resemble the capital H) will prevent the gun from working. But while the device did not work as Blish or John Thompson believed, through a coefficient of differential friction, it did work. I've forgotten the fine details, but years ago I read an article about an experiment done in which a Blish device was procured for a Thompson, the "ears" -- which are on the outside and fit into slots on the inside walls of the receiver, the forward section runs at a diagonal angle - - - - were removed, allowing the Blish to connect the actuator to the bolt but not engage the receiver. The weapon had previously run about 800rpm, but with the disconnected blish, it ran about 200rpm faster, about 1000rpm. I've forgotten exactly how the engineers came to this conclusion, but they reasoned it worked not because of anything to do with friction, but because it formed a sort of lever.

    The later M1 and M1A1 achieved a lower rate of fire because the recoil spring and bolt mass were designed to keep it running slow. While the Blish lock was controversial, it did .... sort of .... work, but in the end it made the gun unnecessarily complex, and I think the fact the M1 variants worked fine prove this.
     
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  18. derek45

    derek45 Member

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    EC528E09-8181-4007-B313-F2B34840FED8.jpeg
     
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  19. AlexanderA
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    AlexanderA Member

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    Regarding that picture of Churchill with the Thompson, notice that the bolt is forward and the drum is in place. The drum cannot be inserted with the bolt in that position; therefore, it must have been inserted while the bolt was pulled back. The further conclusion is that, at the moment the picture was taken, the drum was empty of ammo. Either the gun had been fired so as to empty the drum, or the drum was empty in the first place.
     
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  20. Jim Watson

    Jim Watson Member

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    Delayed how? The one I shot appeared to be straight blowback from an open bolt. I have not heard mention of API in a Thompson, but it may be in there.

    Thompson tried to Blish the .30-06 Autorifle, too.

    And that got me to thinking about the Searle system in the Savage pistols.
     
  21. Jim Watson

    Jim Watson Member

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    I wonder how much the drum spring calibration worker got paid.
     
  22. Tommygunn

    Tommygunn Member

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    The M1 versions did not use "delayed blowback," they achieved a @800rpm (maybe a tad faster) rate of fire with a heavier bolt and a recalibrated recoil spring. The army didn't want the 900-1000rpm rate the earlier 1921 versions obtained. The army really didn't care how the slower rate of fire was obtained, they just believed it was more controllable.
     
  23. Tommygunn

    Tommygunn Member

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    Stolen from off the net; a disassembled Tommygun. The bolt is shown above the stock and the bronze colored "H" device is shown above that, and the black actuator is above the H (Blish) device.
     

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  24. Brubz

    Brubz Member

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    Looks like a photo op to me I wonder if Churchill ever fired that weapon?
     
  25. CapnMac

    CapnMac Member

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    Probably the same labor rate as the rest of the factory.
    Have to wonder what the testing method was. Like a jig with a torque measurement? Which would allow for springs coming from a vendor having a variable range of tolerances.
    Mind, now I'm wondering if an engineer stopped and calculated the weight of all the rounds, assigned a value to the friction co-efficient to work out the needed amount of inch-pounds wanted. To define the torque spec for the helical spring.
    Which would have wanted a lot of working out equations on a slide rule.

    If not that one, specifically, there is a photo of WC blasting away at a range with one.
     
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