Slow Motion: Frommer Stop

This week’s slow motion gun is the Frommer Stop, put into production in 1912. The Hungarian designer Rudolf Frommer was responsible for a series of long-recoil pistols, of which the Stop was the last and best. It is chambered for 7.65mm Frommer, which is identical in size to the .32 ACP but loaded slightly hotter. Stop pistols will generally run reliably on .32ACP as long as it isn’t underpowdered. Anyway, it was a far over-engineered design, with a 3-lug rotating bolt to lock, and a long recoil action. It was adopted by the Austro-Hungarian military and saw service in WWI. Without further ado, I present the Frommer Stop:


  1. states that also .380 Auto (9x17mm Browning Short) was also produced.
    The Frommer Baby pocket pistol was developed from Frommer Stop.
    Later Rudolf Frommer abandoned long-recoil principle in favor of simple blowback in Frommer Liliput pocket pistol and Frommer Model 29.

    I am wondering: is this principle of operation useful for Magnum handgun cartridges like .50 Action Express?

    • Saying .50AE? Oh boy…

      I think you aim to reducing recoil energy thru long recoil concept. It may or may not happen depending on design conduct; if impact of bolt/barrel action is cushioned at travel’s end, maybe. It would be fancy pistol for sure.

      I can see some difficulty with such fat cartridge pumping up and down since it has to clear recoiling barrel. It could lead to snubbing the bullet nose and/ or weak barrel in chamber area. I was once conceptualizing long recoil mechanism for .50BMG and ended up with dropping & rising magazine.

    • Take a look at Gabbet-Fairfax Mars and his .450 Mars Long, which energy-wise borders on .44 Magnum – with today’s metallurgy I think the .50 AE long-recoil gun is fully possible. The question remains – WHY, on this God’s Earth would anyone want one?

      • The British military reports on the Gabbet Fairfax Mars came up with the remark that was repeated for the .55 Boys anti tank rifle:

        Anyone who fired it, had no intention of repeating the experience.

        Both Gizzly and AMT managed to put the .45 Win mag pistol round into big 1911 style pistols operating on short recoil. The only thing to be gained from going to long recoil is the addition of the impact of the recoiling barrel at the same time as the impact of the slide at full travel.

        • From what I read, none of those big calibre guns ever made into considerable sales. Desert Eagle… I’d rather call it Rocky Mountains Eagle – that’s where it could get used. Unless you come real close to grizzly, carbine or slug gun will be always better.

          Actually, recall seeing picture where polar bear was done with .44mag snubbie; it was at real close range.

          • Hi Denny,
            I’m not sure of sales figures for the pistols from the last 40 years or so, but a magnum auto is something of a looser from the very start; there’s a massive outlay up front to get the design debugged, and then sales are going to be pretty low.

            There’s actually very little you can use them for – they’re too big for carry, too slow for practical, too unpleasant for much target use

            A big revolver takes much less debugging, and has much better ergonomics, and accuracy potential. Or a TC contender can fire the same and bigger rounds in a cheap and cheerful package.

            The possibility that I can see for long recoil is in very compact carry pistols.

            Ian reviewed the new little pistol which pulls cases out of the back of the mag and elevates them to feed – so long as the bullet didn’t stay behind in the mag, and the powder go everywhere.

            a lug on the bottom of a recoiling barrel, shoving from the front of a round, might be a more effective way to achieve reliable feeding in a really tiny pistol, where an inch and a half of extra barrel length is very important.

            the multi lugged barrel of the Colt 2000 or the Obregon would allow a browning slide to be used and would do away with the need for the seperate bolt head,

            Where to put the long /========/ shaped madsen style cam track that controls the barrel locking and unlocking, would be a problem

            Even in that form, I don’t think that a long recoil would achieve anything that couldn’t be achieved more easily by a little “U” shaped yoke dragged along by the slide, and almost everything else copied from an H&K P7 M8 finger warming device.

          • You know Keith, just as you like variations and unusual designs, so is with me. I like variations, they enchant the world. Ian is doing excellent job by bringing this stuff up and we are here to chat about it.

            As I seem to peddle at times bit vehemently my views, it does not mean I am not open to thoughts of others. Same way it is good to have some opposition for debate dynamics.

  2. Way over-complicated for a .32, but I find it very interesting to see the various approaches designers took when no one actually knew much about making auto pistols.

    J.M. Browning got it right, or at least hit upon the principles that would become the commonly used ones–but was his just a lucky guess?

    • Simply Browning achieve the biggest commercial success, so other starts to mimic there design to like attractive for potential users. There is also other blowback pistol style with all the mass of slide behind breech – see for example S&W Model 1913.

      • Damnation with faint praise there.

        I know that it is frequently argued in books, that Browning did not come up with any operating system of his own – blowbacks, short recoil, long recoil, gas operation etc were all variously dreamed up or stumbled upon by others.

        One of Browning’s many contributions though, was the slide which we see on most auto pistols today.

        Unlike pistols like the luger, Mauser C96 Lahti L35/M40 etc which have a barrel extension which carries much of the mass, but which stops after a few milimetres of travel, and a light bolt which has to move very fast to have sufficeint momentum and energy to complete the operating cycle

        The Browning slide breaks away from the paradigm of making a lever action or bolt action rifle into a semi automatic pistol, and has a combined slide and bolt, which travels all of the way, so it doesn’t need the accelerator that say a Luger or a Lahti has, it also has the mass (without making the gun unduly heavy) to be able to do its moving at a nice leisurely pace, allowing magazines which are comfortable to fill, plenty of time to raise the top round of a full stack into the feed lips (a lahti, by contrast has hideously stiff mag springs to get that top round up there in time – as well as to overcome the friction due to its steep rake)

        Although the early iterations of the slide were retained by a cotter which could possibly break, allowing the slide to fly back and hit the firer, the version developed for what became the 1911, provided excellent protection against flying off, and a large area to act as a stop surface.

        Even if Browning had failed to make a commercial success of the slide himself (he was very successful and very astute commercially), the slide would still have been picked up, there really isn’t another pistol layout that I am aware of that can rival its strength, simplicity, protection for the firer and most of all mechanical eficeincy.

        Although not popular for service rifles, with only a Volksturm that I can think of using a browning style slide, the slide idea has been adapted very successfully to SMG use, resulting in savings in weapon length without compromising barrel length or operator safety.

          • Browning also held a patent for a one piece slide and bolt – which slowed the wider adoption of the slide.

            The “overhung” bolt in late and post war British prototype SMGs and the more widely circulated post war Czech SMGs, Uzi, Berretta Mdo 12 etc is development of the slide idea.

  3. I originally thought the Stop looked bulky and funky-looking, but after learning the mechanics of it, it grew on me.

    It’s the second cousin to my short-recoil Auto Mag, and I bet it would be much less sensitive to ammunition and lubricants.

    A Stop upscaled for .44 AMP, .45WM, or .50 AE would be righteous… the locked breech would have no problem holding the pressure, and the long recoil action should be a lot less persnickety than the Auto Mag.

    And, hey, a Stop would be the logical match for my Remington Model 8…

  4. Friend of mine had the .380 (9 mm kurz)version. Joy to shoot.

    Why no one has built one of these in a larger, more powerful caliber has always been a puzzler for me.

    Could be that the long recoil hits the shooter on heavyer calibers.

  5. I’ve never fired a rotating bolt action pistol, but it would seem to be better control wise than the link system in the 1911.

    • Rotating bolt or rotating barrel(I know and read well what you say)?

      Lets look at it for second: on ‘conventional’ (Browning type) pistol you have slide and barrel – all the mass you can get to move. They coast and resist impulse by their inertia mass. With Frommer type pistol you have barrel and fairly light bolt to move while ‘slide’ is stationary. Do they soak in same amount of momentum/ energy?

      On other hand, it is known and said repeatedly that rotary barrel pistols manage to absorb more of impulse due to contact with stationary cam. Well…. he we have it.

    • Some details noted while reading referenced source:

      1. Frommer was never technically educated – in fact he was business/ financial executive who is credited with saving FEG factory in time of financial crisis,
      2) he drew substantially on talent of established people such as Krnka and Roth.

      His earlier designs prior to later and more successful Stop were clearly indicative of, although great curiosity, however evident in-aptitude in firearms trade. They were just out of touch with barrels sitting high up like gooseneck.

  6. Thanks Ian,

    I’m looking at the Stop in a whole new light now, it actually appears to be a very competant little mechanism. Still way over engineered for what it is firing, but it seems to work really well, with no silly bounces like the Mauser C96.

    I’m also surprised that the Stop achieves a very low bore axis, especially compared to Frommer’s earlier pistols.

    It’s interesting that you describe it as being comfortable to fire, The Remington Model 8, the Browning shotguns and the version of the browning still being produced by Franchi, all have a reputation for lots of felt recoil.

    Are you going to be doing a disassembly vid of the Stop?

  7. Did you know they made these full auto, with 25 round magazines, and turned them upside down in a mount similar to a Villar-Perosa?

    Here’s the mount:

    Sooo much brass.

    It is an interesting concept with these two small caliber SMG’s. Back when they were developed, battles still resulted in having to meet head to head. Little guns, smaller than Maxims, with obscene rates of fire at short ranges did seem like an interesting idea…


  8. An elegant mechanism in a rather inelegant package. I had the good fortune to acquire one of these about 35 years ago from a man who probably brought it back from the war (sadly,I never got to meet him directly as I think his widow was selling it). Sort of a waste of a mechanism on an inadequate cartridge. The complexity of take down and the extensive amount of machining combined with an underpowered cartridge makes one wonder “what were they thinking?”. Especially as a military handgun. Still, I appreciate the genius of the man who designed it. It likely wasn’t his fault that it was built in a cartridge that didn’t need that level of lock up.

    Still, it beats the Nambu type 94 for elegance LOL.
    Thanks for the video Ian.

    • “underpowered cartridge”
      I suppose that Frommer wouldn’t make special cartridge for his pistol but use wide-available one and the .32 Auto and .380 Auto was one of the most popular cartridge in the Europe in early 20th century.

      • Yes. Also, the notion that .32 ACP and .380 ACP are “underpowered” is mostly much later post-WW2 thinking. In the late 1900th and early 20th century even weaker cartridges such as the .32 S&W Long and 7.5mm Nagant were commonly used by both military and police. Back in 1912 there was very little experimental evidence that those cartridges were inadequate for self-defense (which was the primary function of military pistols even back then). Some would say that there is still very little scientifically acceptable evidence of that (most of the evidence pointing to such conclusion is what scientists call “anecdotal”).

  9. My uncle, who drove ambulance in the 3rd Army (the only unit he ever identified) brought one of those contraptions home upon cessation of hostilities and gave it to my father, who went the other direction and brought home nothing but himself. It lives at my place now, and I get it out every few years and run a few magazines thru it. It has, to my certain knowledge, had no maintenance but an occasional bore cleaning since 1945 and yet still functions perfectly with ball ammo (hollow-point ammunition absoultely will not feed, hardly a surprise) and is quite accurate for a small 32-auto with itty-bitty sights. Things can actually be hit with it, upon demand, when the shooter does his part.

    These have grip safety only, no thumb safety.

  10. Ian, I’d love to see the .45 Savage M1907 through you new toy. You already did it with your old one, and it was impressive, but the old camera was too slow to capture the details (mostly shown sea of fire around the firer’s wrist :D). With this new one, that would be a sight to behold.
    Anyone agrees with my motion?

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