RIA: Thompson Model 1923 Autorifle

One of the very early entrants into the United States Ordnance Department’s semiauto rifle trials was the Auto-Ordnance Company, makers of the Thompson submachine gun. For the rifle trials, they designed a .30-06 rifle using the same Blish-locking principle as had been applied to the SMG. Since the Blish principle doesn’t actually work, this resulted in what was actually a delayed-blowback action which extracted at very high pressure.

The Thompson Autorifle, as it was called, used a very coarse screw to delay the bolt opening, and required oiled felt pads in the magazine to lubricate the cartridges as they fed. It was a particularly long and unwieldy rifle as a result of it’s unusually long receiver, and is known today for having ejection so forceful that it could actually stick cases into wooden planks placed close to the shooter. Needless to say, it did not fare very well in trials and was dropped from consideration not long after this, the Model 1923.


  1. The violent ejection is a feature: it discourages the soldiers from “bunching up” in combat and encourages the use of helmet… 😀

  2. The front end wood and metal looks like it was copied from the 1903 Springfield. Might even be interchangeable.

  3. One of the ways to get closer to learning what does work

    Is to learn what doesn’t work, and why it doesn’t, and to move away from those ideas that don’t work.

    Had very slow helixes/long pitch threads been faster and cheaper to form…

    they’re expensive to form because you either have to shave, broach or swage them very slowly (as in rifling) or mill them.

    … then the Thompson Blish, could have found a more complicated way to do what De Kiraly achieved with an accelerator arm and Vorgrimler did with rollers

    which is to accelerate part of the mass of the bolt

    I’m relieved that Blish didn’t try to introduce a hamster and its exercise wheel into his delay mechanism as well.

    • “they’re expensive to form because you either have to shave, broach or swage them very slowly (as in rifling) or mill them.”
      Kalashnikov designed screw-delayed sub-machine gun – Kalashnikov sub-machine gun (1942) /not to be confused with Kalashnikov sub-machine gun (1947)/ –
      it was not put into production because it was too complicated manufacture-wise for such wide-issued weapon like sub-machine gun in RKKA.
      Finally PPS by Sudayev was put into production – 7.62×25 sub-machine can be simple (pure) blow-back

      • When 7.62 intermediate cartridge was developed, designers task was to craft weapon to it, Sudayev begin with KISS-approach and simply up-scaled his sub-machine gun (it was done in early 1944)
        (see upper half of 1st photo from top)
        but soon found out that it is not good way (main problem: parts have short life) to craft avtomat, so he switch to gas-operated principle
        (see bottom half of 1st photo from top)
        This weapon was produced in small batch for troop trials, feedback was positive, except that it was considered too heavy, so Sudayev was ordered to design lighter version. He started works, but died (due to illness) before can finish it [this design is known as ОАС (OAS)]

    • Back in the days when Agnelli family members were known for engineering excellence, rather than for having seats on the united state Fe’ral Reserve Bank, or getting their stomachs pumped after overdoing the substances…

      One of them came up with a neat rotating bolt delayed blowback system
      of the Villar Perosa type.
      it’s British patent GB191330077A

  4. Let’s face it, Thompson was maybe the unluckiest gun designer in history. The timing was all off, his best stuff was between two World Wars, and he is associated with Prohibition era gangsters, and didn’t live to see that the Brits preferred his design to their STEN.

    • “is associated with Prohibition era gangsters”
      What a irony considering that Thompson sub-machine gun was advertised as anti-bandit gun.
      As side-not: so far I know sub-machine gun is associated with prohibition era gangster due to 1930s movies, in reality they preferred BAR

      “was between two World Wars”
      Time after (big) war is never good time for fire-arms manufacture seeking military contracts – budgets for armament are cut and who would buy brand new weapons when can buy surplus at bargain prices?

      • so far I know sub-machine gun is associated with prohibition era gangster due to 1930s movies, in reality they preferred BAR

        Correct. The first major purchase of TSMGs other than the U.S. Post Office (which bought them for its Railway Post Office cars) and Wells Fargo (for armored car duty) was by Warner Brothers, in 1929, for filming.

        They bought 25 M1921s, and used them incessantly well into the 1960s. In early productions, such as “Little Caesar”, you can see they have the blank-firing attachment on the muzzle. Later, they were modified with bore restrictors to allow their use with blanks without the rather bulky attachmemt.

        In 1968 Warner’s sold their remaining serviceable M1921s (14 in all) to Stembridge Gun Rentals, where they were refurbished and continued in use in the spate of “gangster” movies made in the 1970s, such as Dillinger (1971 AIP) with Warren Oates.

        Thompson had 20,000 “parts sets” of M1921 TSMGs made by Colt in 1921-22. When the British Purchasing Commission beat a path to the Auto-Ordnance Corporation’s door in 1940, just after Dunkirk, there were still over 19,000 M1921 sets still in inventory from that original production run.

        The only verified users of TSMGs among the criminal fraternity were John Dillinger (who stole several during his prison breakout of Michigan City Prison,Indiana, on 26 Sept 1933), and Al Capone’s mob, who used two TSMGs in the infamous “St Valentine’s Day Massacre”. Capone, BTW, obtained the two Thompsons from the Cook Co. (IL) Sheriff’s Department (which he pretty much owned), and when not in use by one or more of his hired thugs, they were kept in a hidden closet in his mother’s house in Cicero. They were in fact the only two in criminal hands in Chicago during the “Roaring Twenties”.

        BTW, George “Machine Gun” Kelly never used a Thompson. In fact, he never used any automatic weapon. The “Machine Gun” monicker was thought up by his common-law wife to cash in on his notoriety after he was arrested for his one semi-successful crime, a kidnapping, and sent to prison for 25 to life. (Tradition holds that she ratted him out herself for the reward.)

        As for criminals’ preference for the BAR, it was based on two factors. First, the .30-06 rifle round would penetrate car bodies, light to medium building materials, and supposedly “bulletproof” vests as used by bank and armored-car companies, which the .45 ACP round of the TSMG just wouldn’t.

        Second, unlike the Thompson, which was a brand-new weapon in relatively short supply, the BAR could easily be obtained, complete with ammunition and accoutrements, by simply breaking into the local National Guard Armory. And there were a lot of those around, with a lot of BARs still in crates, in Cosmoline, having been delivered in 1919-20 and in most cases having never even been unpacked. And .30-06 sporting ammunition was easily obtainable, while at that time the .45 Colt automatic was still pretty much strictly G.I., hence there wasn’t as much .45 ACP commercial ammunition around “over the counter” as you might think.

        As with the whole “assault weapons” thing in the Eighties and Nineties, the Thompson’s legendary status as “The Gun That Made The Twenties Roar” was largely due to its exploits on Hollywood sound stages and back lots.

        Firing blanks.



        • What about the Mexican National Police (AKA Federales) who appeared to have purchased a bunch of Model 21s, some of which seemed to have been diverted. I learned of these while Serving in the Air Force in San Berdoo, when I was offered several by a Local Biker Gang for $500.00 each. They even had the Mexican Armory markings on the cases.
          I have always regretted not having the available cash for such an investment, as My State of Record, allowed class 3 weapon ownership

        • Don’t forget the Charlie Birger gang and the Shelton Brothers gang of Southern Illinois. troytaylorbooks.blogspot.com>2013/01 https://en.m.wikipedia.org>wiki>Charles… My grandfather grew up next door to the Shelton family farm. He remembers how the Shelton brothers would paint red circles on the trees lining the road near their farm and practice drive by shooting. My grandfather said the rattle of submachinegun fire was quite normal.

      • My understanding of the MAS-38 is that it a cross between the pivoting recoil mechanism of a Remington Model 8 and the buffer tube of an AR-15. They angled the buffer tube to fit in a conventional stock and then angled the bolt face so it was perpendicular to the bore axis. Perhaps friction and a dropping mass played into their thoughts. The Finnish Jatamatic went the other direction and had a rising bolt and is said to be good at recoil mitigation.

        Shotguns use friction rings to slow the reciprocating mass more under heavy loads than under light loads. They seem to work well at providing reliable functioning, but shotgun pressures are much lower.

  5. Its wonderful that these rare old guns exist. For me, at least, I was even unaware they did exist! While I could never afford the real deal, I make my own display stuff and it gives me about 75 percent the satisfaction of owning the real thing, but Ian, you and RIA giving us a close up view of the real thing is beyond awesome, and I hope it sparks interest in collectors to help our RIA and the sellers. Price for these guns is irrelevant, they are so rare that it is whatever the market bears as they are forever beyond of the reach of middle class folks who only have the opportunity to view them vicariously through you, but the fact is that this is enough for most of us.
    As many of us has said before, thank you Ian for giving us this opportunity to see these wonderful and rare pieces of history.

  6. Did the Blish theory come about because folks back then didn’t have the range of lubricants, synthetic and otherwise, that we use today without thinking?

    • I read (somewhere – so don’t hesitate to approve or deny it) that Blish lock was inspired by heavy naval guns, which recoil length was shorter with full powder charge than with lighter.

  7. There is no “Blish Principle”?

    My resources are limited to what I find on line and have had experience with, but it does seem to be a real thing. Wikipedia’s Blish Principle refers to “stiction”. It states that “In modern engineering terminology, it is an extreme manifestation of what is now called static friction, or stiction.”

    Stiction seems to be a real thing, with numerous examples given. It would seem to be very unpredictable, judging by the examples given and what I have observed personally.

    I’m not disagreeing with the reality of Thompson’s efforts to apply the Blish Principle were failures, but with the statement that it doesn’t exist.

    I am no doubt missing something or taking this too far out of context and would appreciate understanding where I am wrong.

    • The only reason the Blish “Lock” works even as a hesitation system is due to not design, but materials. The “H-piece” was made of a phosphor-bronze alloy similar to that used in ships’ propellors, and the result was a dissimilar-material friction condition between it and the steel bolt body.

      The need for careful lubrication of the H-piece was less to create a static friction situation than it was to prevent a dissimilar-metal electrolytic corrosive reaction over time, especially in storage. I have personally dealt with M1921 and M1928 TSMGs in which the entire H-piece was green due to such corrosion, and rather thoroughly stuck in its slot in the bolt. Penetrating oil and a deft hand with a brass hammer being the only practical remedy.

      In the M1 Thompson of WW2, they initially tried to make the H-piece from steel, because bronze was in too short supply due to naval requirements. The found that it tended not to work, and also tended to fracture itself and the bolt after 500 rounds or so. Accordingly, they simply left it out and made the production version a straight blowback.

      The M1A1 went even further, deleting the independent, spring-loaded firing pin, etc., and changing from a closed-bolt firing weapon to a more typical “SMG style” open-bolt, fixed firing-pin, advanced-primer-ignition “slamfire” arrangement.

      In actuality, the original Thompson was basically a self-loading carbine that was intended for limited full-auto fire. I can personally attest that in single-fire mode, it is surprisingly accurate out to ridiculously long ranges, largely due to its Lyman rear sight. Targets of groundhog size are in serious danger at 200 yards from a 1921 on single-shot.

      The straight-blowback (but still closed-bolt) M1 was still reasonably accurate at that range, even with its two-position “L” flip rear sight (very like that on the early M1 Carbine and late Rifle No.4)

      The M1A1, by comparison, was a near-certain proposition at 75-100 yards once you got the hang of its forward “lurch” when the bolt seared off. Beyond that, forget it on anything smaller than a half-track.



      • “more typical “SMG style” open-bolt, fixed firing-pin, advanced-primer-ignition “slamfire” arrangement.”
        Wait, I always read about late Thompson SMG as blow-back, not advanced primer ignition. Always thought that advanced primer ignition require rebated rim cartridge as in MK 108 https://en.wikipedia.org/wiki/MK_108_cannon

        • Daweo,

          Advanced Primer İgnition is a blowback action which uses not only the mass of breech closing element, but the speed it gaines when returning to full battery situation. Whereas, rebated rim cartridges is another kind of blowback action which uses deeper chamber than usual to get advantage of excess full supported back section of it in which the full case fits and recoils for longer backward distance when fired.

        • Daweo,

          Advanced Primer İgnition is a blowback action which uses not only the mass of breech closing element, but the speed, therefore, momentum it gaines when returning to full battery situation. Whereas, rebated rim cartridges is another kind of blowback action which uses deeper chamber than usual to get advantage of excess full supported back section of it in which the full case fits and recoils for longer backward distance when fired.

          • I realise that this is hair splitting,

            but in open bolt SMG use, the bolt is usually the same weight as it would be for closed bolt operation

            that is to allow for the possibility of hang fires.

            So unlike Becker/ Oerlikon derived cannon, where there is an inch or so of travel within the chamber following the primer being struck. SMGs don’t tend to reap any of the potential rewards of reduced bolt weight that the larger advance primer ignition cannons do.

          • More hair splitting: the rebated rim is required for extraction to work with the extra-long chamber and the backward sliding (recoiling) case. So, significantly lighter bolts can’t be used without rebated rim ammunition.

          • SMGs also need popular, subtle ammunitions with rebated rim to be in “Deepened Chamber” category. Is there any…

          • Let’s put some clarity into this.
            First thing to ask is: “does the bolt (in SMG) stop instantly, once its solid installed firing pin contacted primer”? Answer is: apparently no. It just keeps going for awhile, until cartridge is stopped on its shoulder (of whichever the form it is).

            Next item to think of is a point at which primer is initiated and how quickly pressure in cartridge is building up. If motion of bolt is being “just about” arrested and the pressure is in steep stage of building-up, you used some amount of bolt forward momentum to your advantage. You can call it – partial advanced priming.

            Of course there is potential for some trick around this such as 2-piece bolt acting in stages, but that gets little too complicated.

    • Static friction is relatively new term and it refers to transition between stationary and motion conditions. This is where Blish concept apparently falls in. The “rubbing” motion friction as commonly known (part of rolling and other types) is pretty well known and subject of avoidance.

      Also, it is good to remind ourselves, that contact friction coefficient during motion doesn’t depend on force of normal load, quality of surface finish and speed of motion. To use friction deemed as advantage in firearms is tricky and unreliable concept. This being said friction is always inadvertently present, be it between case and chamber, on locking surfaces or in guide-ways.

  8. This makes the Chauchat look like a better option for a support weapon. Perhaps one would rather get a Mondragon with drum magazine despite the heavy price tag.

  9. I’m curious if a hydraulic buffering system has been used on any small arms. It would seem to me that with modern materials and manufacturing it would offer the ability to reduce the movement of parts (like an operating rod) and to create a very carefully controlled recoil pressure curve in a simple blowback system.

  10. I would imagine the reason for the “Firing Position” stamp was simply to show that it fired from a closed bolt unlike the SMG which fires open. People who had fired Thompsons would have been used to pulling the bolt back to te open position to shoot….

  11. I’m guessing the “Firing Position” mark may have explained itself if you disassembled the rifle. If the mark was visible in the slot, you have, or are assembling it correctly.

    Also I noticed the ejector cover piece also prevents the receiver halves from turning independent of each other.

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