Lewis Gas Operated Pistol (Video)

Isaac Newton Lewis is best known as the designer of the Lewis light machine gun, of course – but that was not his only work in the firearms field. In 1919, he patented a semiauto handgun using the same gas-operated, rotating bolt mechanism as the machine gun. It is a pretty massive steel beast of a handgun, and interestingly fires from an open bolt, despite being semiautomatic only. This is a questionable choice for a handgun, as it substantially hinders practical accuracy because of the heavy mass moving during the firing process, forcing the shooter to have exceptional followthrough to make hits.

That said, this pistol is very well made, and operated quite smoothly (except when the cocking sleeve rotates slightly out of alignment and prevents the bolt from falling). It even has a reversible firing pin. This pistol is chambered for .45 ACP, and is depicted in patents as having a double-stack magazine with a 15-round capacity. The magazine is missing from this example, but I am aware of another Lewis handgun of different design that does have a magazine of this basic type, so it’s not just a patent sketch. The gun is devoid of any markings, and I have no information on how many were made in total – but I suspect the number to be very low – possibly only this one.


    • Cherndog, you magnificent b******d, you stole my POST! šŸ˜‰

      Seriously, I’m wondering if that hole in the backstrap wasn’t for a safety/selector switch rather than a “one function” safety. There has to be a disconnector in there somewhere, and it seems to me that a sliding switch in that hole would be perfectly placed to both lock the sear (thus acting as a manual safety) and if pushed up farther prevent the disconnector from unhooking the sear from the transfer bar, resulting in full-auto fire until the trigger was released.

      This may have been a “proof of concept” platform, with the intent being to develop a locked-breech “machine carbine” firing from an open bolt, rather on the same tactical principle as the Pedersen Device attachment for the M1903A1 Springfield rifle.

      In fact, it would make excellent sense in such a format, firing either a high-power handgun round like the 9 x 25mm Mauser or even an “intermediate” rifle round. As such, the double-column magazine may have been intended to show that there was enough “power in the machanism”, as the British say, to feed reliably from a rifle-type magazine, an important consideration in a full-automatic individual or support weapon.

      Actually, if you look at it purely in terms of action layout, it bears a startling resemblance to the Haenel Maschinenkarabiner series from MKb-42 on up to StG-44. Not to mention the bolt/gas cylinder layout presaging the “overhung bolt”/”hand finds hand” concept of third generation SMGs like the Czech Samopal 23-26 series and the Uzi.

      I’d never heard Lewis was even interested in pistol design, but a pistol prototype and patent would make a pretty good “demonstrator” for a meeting with the Ordnance Board.



  1. A similar Lewis handgun with gas actuated lockwork; US Patent No. 1430662.

    Seeing this full metal construction with “Gas Trap” lockwork, one can not help thinking, if the cause of choosing the “Open Bolt Firing”, happened for it getting too hot quickly and cooking off the chambered round in case of selecting “Closed Bolt”. Then, one begin to think again, what would be the cause of unusing the wooden handle plates instead of unitary metal handle frame.

    • US Patent No. 1430662 shows the missing backstrap piece to be a safety, which rides up in front of the bolt to hold it to the rear. (Page 7, line 45)

    • that was my thought as well, this is a good proof of concept for the action and stability of it at the smaller size compared the the Lewis gun

  2. I’m pretty sure this is what you call a “technology demonstrator” and not meant to be a practical handgun. It’s finished up nicely and portable so you can throw it in a bag and show it to potential investors, but I believe what was being “sold” here was a design for a light machine-rifle.

    There are a series of related patents:

    US1430660 – Application Serial No. 263,823

    US1430661 – Application Serial No. 263,824 – Mentions App. No. 263,823 in text

    US1430662 – The so called “pistol” patent – Mentions App. No. 263,823 in text

    US1439903 – Mentions both App. No. 263,823 and 263,824 in text

    US1462972 – Mentions App. No. 263,824 in text

    So, taking these all as a group, you can see that this pistol is most likely a portable demonstrator. Finished up nicely to give investors something pretty to look at. ^__^

    • Mostly making good sense, but;

      – Why covered by a pistol patent…
      – why semi auto only…
      – And why magazine in the handle frame…

      • I think Lewis may have been trying to sell it as a submachine gun concept. A gas-operated SMG firing from an open bolt could be made smaller and lighter than a straight-blowback/advance primer ignition type, simply because with a bolt locked at the moment of firing you wouldn’t need the heavy bolt characteristic of blowback SMGs to keep the rate of fire within rational bounds.

        NB1; Generally, anything over about 600 R/M falls into the “uncontrollable” category; 400 R/M was considered reasonable by most armies back then.

        The Thompson, which was the only SMG around commercially back then, was often criticized for its weight and average 800 R/M RoF, in spite of the supposed “Blish hesitation lock”.

        NB2; I’ve fired M1921 and ’28 “Tommies” with the lock, and M1 and M1A1 straight-blowbacks without it, and never noticed much difference in RoF. The one thing I’m sure of is the old myth about leaving the Blish lock out and firing a ’21 or ’28 without it is a good way to fracture the bolt. The “H” piece needs to be in there, kept clean, and lightly lubricated; I used powdered graphite.

        Lewis may have felt that a lightweight, compact SMG that had a more manageable RoF than a Thompson might be a saleable item.

        As for the “up through the pistol grip” concept, it’s older than most people think. The British prototype MCEM SMG in 9 x 19mm used it in 1943. It also had the “finger-hole-in-the bolt” cocking setup later used on the U.S. M3A1, as well as the now-common “overhung bolt” encompassing the barrel.

        And the Mexican Mendoza SMG of 1945 also had the magazine in the pistol grip. It’s practically unknown, due to being a blow-forward that never got past the prototype stage. (Come to think of it, it would make a good FW video if Ian could find one to take apart….)

        I’d say the Lewis pistol/SMG concept is worth looking at even today. It could provide a lightweight, reasonably accurate and less expensive alternative to the MP-5 series.

        Add a hammer to drive the firing pin ala’ the Kalashnikov, and it could be made a selective-fire with good accuracy in semi-auto (firing each shot from a closed bolt), and on full-auto firing from an open bolt to allow the barrel to cool between bursts (like the FG-42 and removing one of the main aggravations of the MP-5 family).

        You could probably make it and sell it for a fourth of an MP-5’s cost and still bank a profit, too.



        • “Iā€™d say the Lewis pistol/SMG concept is worth looking at even today. It could provide a lightweight, reasonably accurate and less expensive alternative to the MP-5 series.”
          Why to use gas-operated sub-machine gun when blow-back and delayed-blow-back is enough?
          For modern light sub-machine gun see PP-2000:

  3. I must confess I didn’t even know the Lewis machine gun had rear locking lugs, which surprised me it’s not like I haven’t looked at one before. I suppose I must have been thinking Fg42, then been concentrating on clock type springs, cooling sleeves, reversible firing pins and the rest. When I first looked at the title- Lewis gas operated pistol, I immediately thought gas delay I.e. The title along with it’s appearance “The upper tube looping over to the rear of lower one- Made me think it was diverting gas to delay the bolt” Perhaps in a ineffectual way, compared to other designs.

    Anyway, 15rnds double stacked .45Acp mag- Nice. Beautifully constructed, understandable design conception- Given the Lmg- That is well executed, in miniature. Most impressive.

    I had a “brain wave” the other day, if you look at the link below:


    There’s a “model” and rough diagram of my version of the Gerat 06h type system, come up with this awhile ago (There would be added mass running along the top, doubling as a cocking handle engagement piece) my version does the same thing in essence but is easier to manufacture, in my opinion.

    But I crossed it “This was my brain wave” with the Nazi gas delay last ditch (Steyr Aug trigger guard/handle model) And came up with, a further set of forward facing “plate” sections, attached beneath the lower two plates via the roller pins. These terminate with a gas plug, and this fits into a channel beneath the barrel connected to it via a port forward of the chamber.

    This is the interesting part to me- The plug would need to move forward inside the channel when the roller plates contract I.e. Pinch together, given they are attached to the plug- But gas would prevent this, until pressure dropped sufficiently therefore removing the need for a fluted chamber in theory. The system would have a firing mechanism actuated by the contraction of the rollers, and all wiggly parts are stabilized via said mechanism or the trigger/cocking assemblies. And the overall layout is a Fg42 but think Sten’ised- In appearance. Quite pleased, it makes sense to me- Possibly an ideal f/volks rifle operating method. Mentioning it now, given I thought this pistol was operating via the gas delay principle initially- Topical’ish.

    • I haven’t illustrated the “brain wave part on the link” but I hope you get the idea, the extra mass running above would have been attached to the rear “marker pen cap#” one is the bolt face you see- Moving the rear # rearwards, contracts the rollers you understand.

        • Patents… Why do they write all the gobbledygook in the claims, lawyers probably- Keeping them in a job, er… There is a war on.

          Chop, chop.

          • I’m adamant, my creation is potentially a unique and beneficial 7.92x57mm in the category of Sten type waffen.

            Might not be, make one and see very easy- Illegal here.

        • I actually think the word ta is Irish in origin, not Danish. It means yes in Garlic, so it’s a corruption of the original meaning- Non English speakers would naturally say yes to everything, like Poles now- So English speakers took it to mean: Thank you. “There’s a bomb under your lorry” Yes. “You have won the lottery” Yes. Because it tends to be used on the Irish side of the Island- Most populated by Irish immigrants, not Ireland as an Island, Britain.

    • Good idea. Somewhat similar to “Friction Based”, Browning A5, Remington 1100 Breechbolt speed regulator rings, or Fabarm rubber “Pulse Piston”.

  4. If that is what it looks like (and not something that was built along the way to developing a select fire weapon), then I feel like I’m looking at the work of someone who was determined to avoid a good if it was the last thing he did. It looks like a costly mechanism to manufacture; but given how overly elaborate the 1919 Thompson was, with the Blish lock, and the barrel fluting, I don’t how much more expensive a “lewis machine carbine” would have been.

    If a .45 ACP select fire weapon had been put into production, even if it had not met with commercial success, it could have served as the basis of future scaled up automatic rifle designs; especially given the ease with witch the mechanism could be adapted to allow the selection of either open or closed bolt operation. Think about it, American infantrymen could have gone into world war II with something like an FG-42 chambered in .276 Pedersen.

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