Frommer Prototype Semiauto Rifle (Video)

Rudolf Frommer was a self-taught engineer and firearms designer who worked his way up through the FEG concern in Budapest to eventually hold the position of CEO. During this time he developed a series of long-recoil, rotating-bolt pistols culminating in the Frommer Stop, which was adopted by the Austro-Hungarian military. At some point during this time he also produced this prototype rifle, which is similarly a long-recoil rotating bolt design. I have no information on its production or performance, but I will give you as much of a look into its operation as I can.


  1. Until somebody comes along with info on this rare old iron, let me suggest that you do a tutorial on cleaning and freeing-up stiff guns. There’s a lot of antique cosmoline, whale oil, and goosegrease clogging up interesting weapons, and if you demonstrated how to melt/dissolve/work around it, along with treating rust and grit, it would be a popular video. Throw in some wisdom on tools too; amateur gunsmiths can get up to funny tricks if they aren’t supervised.

  2. My childhood experience with whale oil was among the best penetrating and lubricant I had seen. Better than WD 40 at least. It was antique and irreplaceable then, of course.

  3. That sliding cover resembles Frommer’s patent AT136848 – Fig. 1 shows a little spring-loaded thingy (9) that’s supposed to lock the cover in open or closed position (using notch 10 or 11 respectively), and it’s mounted at the rear of the middle opening, exactly where the real thing leaves a hole.

    • AT135063 seems relevant as well – it explains what that little box next to the bolt handle is for (there’s a spring-loaded hook under it, that prevents the barrel from moving when the bolt handle is pulled; supposed to help with extracting stuck cases, so they can’t just pull the barrel along).

      • For english speakers: US1991302

        If this feature is still working in this example, closing the bolt and pushing the bolt handle fully forward should free the barrel to move back under spring pressure.

        Removing stuck cases is one of the problems with long recoil guns.

      It’s pretty simple, actually – because the bolt handle moves, holding the gun wrong can result in injury.
      The original design (AT125344) had a raised rail, but that didn’t actually stop people from putting their fingers in harm’s way.
      So Frommer updated the design to make touching that part actively unpleasant.

      • The bolt-retraction handle appears to fold, as well. This would make sense, as in a long-recoil design the bolt and barrel all recoil together.

        A folding bolt handle might save the shooter a sharp rap on the knuckles- or the nose- if they had one or the other in the wrong place.



        • It appears that the charging handle on this rifle would have been better if it was on a separate track and therefore did not cycle with the bolt during firing!

    • Some more that look “suspicious”:
      AT129889 – Safety- and Firing-Unit that can be removed in one piece
      AT129888 – Spring Arrangement for long-recoil guns
      AT126237 – Rotating bolt for self-loading rifles
      AT124373 – “Grip arrangement for self-loading rifles” (the Bolt handle)
      AT125344 – Dust Cover

      I think that’s everything I’m going to find on Espacenet

    • And looking at the photos on the RIA homepage, I think I just realised what’s wrong with the bottom cover.
      That part I mentiond? It’s there, but it’s installed wrong – it’s too far forward, so instead of closing the opening when the cover is closed, it partially obstructs the vent when the cover is open.

      • I believe that the bottom ventilation cover is simply installed backward. I’m going to guess that this firearm was discovered disassembled and that part could fit either way. The patent, (US1913254), shows how it should work.

        • I took a closer look, and I think you’re both right and wrong about the bottom cover:
          It *is* installed backwards (the textured part at the front appears to be at the rear in Fig. 3) but turning it the right way around would not solve the problem – the center section is simply shorter than the hole it’s meant to cover.
          (You can see this well if you pause the video while Ian is moving the cover at 7:14)

          • I agree that there are part(s) missing. You can see an empty screw hole and a relief cut in the stock for something under the cover. That would probably seal it up nicely if you turned the cover around the right way.

    • And if I had thought to search properly, I would have had the corresponding US patents as well…

      Frommer has more patents from the appropriate time, but I think these are the only ones relevant for this rifle.

      • US1913254 – Barrel cooling vent cover
        US1892259 – Saw toothed hand guard
        US1991302 – Barrel to Frame Lock, activated by pulling back on bolt handle
        US1911859 – Fire-control group with outside cocking lever (double-strike capability)
        US1809741 – Earlier patent for bolt-handle that disconnects from return spring when pulled back. No barrel to frame lock in this one.

        I know of one other Frommer rifle patent: US1997954 This is for a set-trigger fire-control group. I would assume this is for a commercial hunting version of this rifle.

        • I’m not entirely sure, but I think the set trigger patent refers to another rifle entirely – Frommer was also working on break-barrel sporting rifles at that time.

          • On second thought, you’re probably right – the set trigger patent shows the same sort of “module”, and that wouldn’t fit in the hunting rifle I was thinking about.

  4. Looking over AT129889, lever 19 is explicitly called out as a cocking lever.
    That gives me a worrying thought – you said it seemed not to work, but did you make sure to try it with that switch set to “Rep” as well?
    Because that thing is in the right position to interfere with the disconnector…

    • For english speakers: US1911859

      It is interesting that this patent doesn’t mention the fire selector. It would be interesting to know if this is meant to be select fire, or to choose between “repeater” and “single shot.”

      • I’m currently thinking the switch was designed by somebody else at FEG, rather than Frommer himself.
        That’d explain why I didn’t find it searching by name.

        • I’ve not had any luck tracking down information on that switch.

          I did find two Frommer patents for rifles that can be switched between semi-auto and manual operation (AT22099 / US992184 and AT32928 / US952896) as well as one select-fire (AT33469 / US989242 + US985156).
          But none of them match what’s on this rifle.

        • The idea that the fire select switch is by someone else is possible. Frommer died in 1936, only a short time after the last patent was published.

  5. Unfortunately, long recoil guns have to cope with one serious issue and that is to clear magazine lips. In that case barrel must have some clearance machining to it which makes it potentially weak in chamber area. Pity it was not possible to disassemble the barrel to see.

  6. Rock Island’s description of this is appalling:

    ‘Mechanically functions, but operating rod does not always engate bolt properly’ their spelling misstate. For $14,000USD I would want the action to cycle on something that Mechanically functions. They also think it’s gas operated, and use ‘fairly heavy’ rather than flat out putting it on a scale and saying weights 12 pounds (or something). In the condition they also fail to point out the broken barrel band retainer.

    Ian do they consult with you on item descriptions? or are you involved after that is in catalogs and finalized?

    • It’s a unique prototype from the 1930ies – there’s no telling whether it ever cycled reliably…

      (Actually, I suspect it didn’t – if the bolt handle bounces a bit at the end of bolt travel, it disengages from the op rod and the bolt stays at the rear. Note that the original patent had a much heavier handle…)

    • Oops, this was already mentioned above by AMX as AT125344 … so, for those looking for the related patents in english. ^__^

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