Headspace-Operated Prototype Rifle – Yeah, it’s as Weird as it Sounds


Today we are taking a look at a very unusual prototype rifle, courtesy of Legacy Collectibles. I suspect – but have no direct evidence – that this was designed by one Francis K. Young, a man who patented several very similar systems. What makes it unusual is that it operates by having the cartridge case set back in the chamber, either by moving or by physically stretching upon firing. This would never become a successful mechanism for a self-loading rifle, but Young spent many years working on the idea, making a series of prototypes and registering several patents.

Thanks to Legacy Collectibles for providing me access to film this rifle! Check out their YouTube channel for lots of other interesting firearms history.


  1. it seems like he thought he could use the extraction process as initiator of the bolt actuation process. but thats backwards he found out.

  2. Look in the barrel in the chamber area, I would think that the cartridge prob would seperate there because of the way it pulls it. There may be remains there.

  3. It would be interesting to compare the machining on that rifle and the Young prototypes to see if there are similarities in how the machinist approached the work. Handwriting analysis in metal as it were.

  4. This idea can totally work given the same chamber and style of ammunition (straight wall,rebated rim, heeled bullet) as API systems. Because case wall is supported it should be possible to tinker with it enough to prevent case-head separation. Now, straight-wall ammo is probably useless for an infantry rifle, and if scale up I am not sure that API proper would not be a better alternative for comparable cost.

    If forced to apply compare it with more conventional designs I’d call it hesitation-locked design,possibly even tougher than known examples (because bolt is properly locked at the start), but still utterly inadequate for an infantry rifle.

    • I agree. I was heading to similar conclusion in my earlier remark. Cartridge does not have to be with straight wall; with existing 30.06 casing the taper is so slight it could accommodate temporary expansion at short travel distance in order 0.003-0.004″ at diameter (corresponding to 0.21-0.22″ travel).

      • I was talking primarily about “no bottleneck”, rather than “no taper”, as in API systems, like I said. And cylindrical rounds are utterly unsuitable for an infantry rifle. Now can this be made to work with bottlenecked rounds? Maybe, but I wouldn’t hold my breath.

        • The most popular and longest lived iteration of the Oerlikon API blowback autocannons actually use bottlenecked cases. The Type S AA cannons (and the less common FF-S aircraft-mounted guns) use the bottlenecked 20x110mmRB. Note they still use rebated rims to accomodate the API system and a deep chamber the bolt can slide into, allowing the case head to be fully supported before being fully chambered.

          This is likely hard on cases and likely worked better with steel than brass, but did work and is still in use today. It was apparently was more appealing than using a longer, straight walled case instead (and longer receiver), though it did use a rather shallow shoulder at the bottleneck, almost a taper rather than a normal shoulder.

          Compare it to the 20x110mm Hispano cartridge to the far right.

          It would also likely be hard on brass, making reloading less practical. (and the US Army liked to re-use as much of their spent cases as possible)

          That said, such a system, or Pedersen’s own hesitation lock would be well suited to straight or nearly straight-walled rifle and pistol cartridges and new cartridges specifically tailored to the system. (like the .30 Carbine, or the older winchester self-loading cartridges: imagine a standalone Pedersen Hesitation Locked .30 M1918 Light Rifle instead of the Pedersen Device)

  5. You easily forget how influential nearly a century of practical experience with something like automatic rifle mechanisms really is, until you put yourself in the position of someone who has never, ever seen such a thing in a working example. Once you put yourself into the shoes of someone who is completely new to the entire idea and the surrounding issues, well… Yeah, a lot of stuff we’d “instinctively” reject out of hand today seems like it might be worth trying out.

    Not to mention, there’s all the dead weight of the patent system to overcome. I think an awful lot of the “weird” that Ian turns up is due strictly to the fact that most of the obvious ideas were tied up in patents. Can you imagine Kalishnikov trying to build the AK in a world where he had to pay for licensing rights to all the different ideas he built from? Not that the Soviets would have paid a lick of attention to the laws, but… What if he’d had to? Would the AK look even a little bit like what it does, if he’d had to have come up with “new” for everything from operating principle to trigger design?

    I sometimes think that the patent laws need to be done away with, and replaced with something that enables people to build on existing art, while still compensating the original designer. That way, a really good idea like bored-through cylinders doesn’t wind up being the exclusive franchise for one company or man, and you get quicker innovation.

    Maybe some sort of automatic licensing deal, where if you borrow an idea from a registered design, an automatic cut goes to the guy who came up with it? And an “engineer’s court” to determine how much of, say, Smith & Wesson’s new pistol relies on the rights that Colt bought, requiring them to pay a percentage of the sales cost to Colt or the original designer?

    • “(…)Not that the Soviets would have paid a lick of attention to the laws(…)”
      copying and borrowing of ideas was actually encouraged by the trials commission (and the whole Soviet ideology), as all intellectual property in USSR was considered to be property of ‘the people’, or the state. Thus, any state-owned intellectual property could (and must) have been used to the benefit of the people / the state by anyone. And creating a new, most effective assault rifle for the victorious Soviet army was certainly on the top of the list of things, beneficial for the Soviet state at the time.

    • My notion of what to do about the patent system is to abolish it and in its place extend copyright to physical objects:


      By the way, Kirk, do you have any place on the net where people can follow your writings? I’ve seen your comments on this blog, the old Weaponsman (RIP), and Isegoria, and it’s been pretty evident that it’s the same Kirk, largely because the quality of those comments is distinctively high.

      • Monopolised rentier capitalism “got rentier from a newspaper article the other day so I am not an expert” anyway well said, I will read your link again… Main point is monopoly. Good ideas are bought to be made never to happen; what kind of progress is that.

      • I appreciate the praise, but I honestly doubt I’ve got anything of any value to say. I’m just a cranky retired and very cynical NCO, and I probably spend too much time commenting on things, anyway. If there’s enough of my ranting out there that you can identify it by sight, that tells me I ought to be doing something more productive, TBH. Or, at least, that pays…

        I shudder, slightly, thinking about how much there might be. I do tend to go on and on and on about things that annoy me, which is pretty much everything, these days.

        • Well, there’s a reason why they often tell newly minted lieutenants to treat every piece of advice from their senior NCO as a command, and to treat every command given to that NCO as a suggestion. There’s a lot to be learned at that level — it’s where the rubber meets the road in terms of translating grand plans into actions of men and machines — and what can be learned might as well be put in writing. That this is not the fashion makes it even more useful when someone actually does it.

          • To a degree, I think you have a point. Far too much of the “cultural commons” is defined not by the practitioners, but by the administrative staff.

            Why this is, I don’t know. Part of the problem boils down to the fact that the sort of person who becomes an NCO-analogous “practitioner” in all arenas of life is also very rarely the sort of person who spends a lot of time on introspection or thought about what they’re doing. They do, they don’t talk about it.

            As well, most of them aren’t exactly very good at the creation of limpid prose, so the documentation of “what really goes on” winds up being done by the men with college degrees and large vocabularies, who very often are completely in the dark about what is really happening around them. Thus, reality gets “documented” by the delusional who can write, and the men who made it happen wind up forgotten and ignored.

            This is something that’s been going on for a long, long time–Try to figure out whether the Romans marched in step, for example. There’s no evidence that they did, because none of the many authorities who wrote about their military practices thought that such a thing was worth mentioning. Vegetius, for example, is silent on the issue. Yet, you read the histories of their battles, and you’re left with the inescapable conclusion that they had to be doing something analogous, because if not, how did they not wind up bound up and confused while conducting the tactical evolutions we know they made?

            Academics say they didn’t march in step; people who’ve marched in step for mass formation evolutions are all like “Yeah, then how’d they do that?”, while pointing out the historically recorded maneuvers Roman troops made.

            There are two paths to knowledge; one is pure scholarship, taught by academics in isolation from practice. The other is the practicum, learned the hard way and from the bottom up. I think our military (and, society in general…) has drawn far too wide of a boundary between the two, and emphasized the first path I mention much more than they should. You need both, and it’s a sad commentary on our educational system that the men who follow the practicum aren’t writing books about it–Mostly, because they’ve been left unequipped by their background so as to be able or interested in doing so.

    • I agree. Compensate the original designer; folk are going to invent more because of the internet, the current patent lark is analogue not digital so to speak. Should be much easier to share, collaborate, compensate etc… Digital age.

      • Or more folk, will invent more… Even as oppose an “inventor” inventing more; more info available via the internet, bound to happen. Unless we assume the vast bulk of the population are thick and unless you live in a castle and are called Baron such or such your unlikely to come up with anything as you don’t own a library.

  6. I do not consider this concept as misguided per se. Granted there is some 5-6 mm of full material section at the base of casing, it can move back that distance before bursting.

    The problem is the high point at time-pressure curve at this instant. One solution to aid the process might be fluted chamber. Another one could be to create a delay in the mechanism thru additional resistance or combination of both.

    But overall, I do not feel this setup was suitable for Springfield 30.06.

    • Thinking back about that “delay”. He’s got it there in form of cam and pin. For certain amount of distance to the rear movement he’s got to overcome friction at the cam to obtain rotation to full unlock, circa in 1/1 proportion. The friction between pin and cam creates the delay.

      The initial free movement is to set parts in motion (to overcome static friction); it can be quite small and not necessarily detrimental to case integrity. This system should be revisited.

  7. If Young hadn’t thought of this, John Pedersen might have. (J.P. was sometimes just a little too clever.) Certainly Pedersen’s famous folding-block rifle utilizes slight initial cartridge setback, applying it in a more practical way. Could he have been aware of Young’s approach? And thought, “Whooee! I can do better than that!”

  8. Action seems very similar to Pedersen’s “ Hesitation Lock” used in “M51” pistols…Cartridge case recoils as unsopported to a small distance where hesitates and its velocity begins to slow through remaining backward travel… This functionaly, is very similar to “Gas Ram” systems used in VG 1-5 in which, action does not work to keep the bolt locked at instant of when the highest pressure within the barrel exists, but works as a bumper through rotating path to slow the recoil punch… IMHO…

    • I am surprised the Pedersen designed Remingtom 51 pistol (which had a .45 Auto version) was not mentioned much earlier in this thread.
      There are similarities to the so-called VG 1-5. But the important difference in my view is that the Pedersen “bold-head” comes to a complete stop after its first initial travel. The VG 1-5 action works like a blowback, never stopping in its rearward motion. The “Gas Ram”, as you correctly describe, only slows down this rearward motion, working as a gas cushion bumper.

      • Thanks for your interest… If thought, Remington M51 Bolt does not stop firmly at hesitation point… It moves longitidunaly very little distance as camming up… This may be somewhat similar to that rifle’s rotation cam. IMHO…

          • Also 1517483 No. US patent… Strangely Mr Franklin depended upon “Air Cushion” for delay for reciprocating bolt head at both patents.

        • German expert Peter Dannecker did the following analysis of a Remington 51 pistol:
          – The case, bolt-head and slide move 2.8 mm backwards, before the bolt-head hits the stop in the grip.
          – The slide moves another 5.2 mm, before it cams up the rear of the bolt-head out of engagement and takes the bolt-head with it further on its way back, extracting the case from the barrel and ejecting it.

          • Thanks for the information … Could not stop myself adding some thoughts; In fact, 2,8mm free blowback could be accepted as backward ensured limit for the empty case with high pressure inside to go out of chamber without support. This means, Pedersen’s “Hesitation Lock” starts its locking or, quasi locking mission at instant when this need ends… Beyond that, the bolt piece is forced to cam up for so called 5,2 mm as, some 1 mm dragging itself over the angled cam surface as slowing the slide recoiling speed. This also means that, “Pedersen Hesitation Lock” is not a lock but a mechanical slide speed reducer working nearly same as “Gas Ram” of “VG1-5”…

            Franklin K Young also stated an “Air Cushion” slowing the initial kick back of the bolt head in his patents… This might be the difference from “Pedersen’s Hesitation Lock” since having some slowing at bolt’s initial free recoil… If it had really worked so… IMHO…

      • Once again.
        Where does this thing about an acceptable gap of 2.8-3mm come from ???
        Look at least the SAAMI specifications.
        With a displacement of up to 0.3 millimeters (if no measures are taken), transverse cracks can (and will) appear on almost all rifle cartridges.
        On pistol, this value is greater, 0.3mm is still acceptable.
        But the same P51 pistols tearing brass. Not all and not always, but they tear.

        • Sorry… But if you do not know the difference between ; Permitted Headspace “Gap” and permitted “Free blowback” distance at blowback arms, please do not comment here… Other commentars may take you serious…

          • “…the difference between ; Permitted Headspace “Gap” and permitted “Free blowback” distance at blowback arms…”(C)

            It’s priceless!
            I’ll go and write it down on the last page of the tutorial.
            Are you already writing a book about this?..
            I would like to read.
            At least to laugh. LOL

            Stop breeding nonsense.
            And then You and the truth someone “correctly” will understand.


          • Stiven… We are all friends. There is is not teacher here… We all learn from each other what learnt, what experienced, what seached, what remembered… Nobody pretends like teacher… Be polite… Be friendly… Be humble and serious… Your package of knowledge may not reach even to the level what other commentars had forgotten… Try not to underrate the others… No one here would deserve it… Please be respectfull… Remember that, respect can not be demanded without having it… Have a good year…

  9. I really like that because it is an example of… Early ideas. I mean;like the primer lark etc… So fair play to Francis. On the face of it, not having a gas system etc is “better” if you could do it, without it I.e. Open the bolt etc, that would seem optimal. Were as having gas ports etc would be sub-optimal… In comparison. At least on the face of it. In principle. Theory, etc. That potato digger gun used gas for example… So maybe they kinda thought this/primer lark was better (untill folk eventually made different formats, to accomodate gas operation…) The roller delayed thing, still tries to beat “gas” but with a better “format” sooo… I mean, maybe gas only really took over because it was made more reliable eventually; M1 Garand etc.

    Bet Francis would have like Niti “Nitinol, yes that again” could have maybe put a “spacer” of that around the case base… Proprietary cartridge sure, he he. But heat would cause it to say bend, the spacer would fold say… ) type shape, thus perhaps operating his system. Case then ejects, end of that piece of Niti.

    Not suggesting doing that is better than gas or this, he he… Just saying bet he would have fiddled with it; had he had any in the 20’s. Lots of fiddling. Did just occur to me though, that Nitinol might be able to be used thus however; in cases, in such a way.

    • Having thought a bit about how to perhaps invent new guns “prior to gaining any in depth knowledge via here) it does fascinate me to see all the other attempts- So I especialy like the early stuff, he he. I did re-invent a sort of poor Lewis gun bolt out of toilet rolls “without having seen one” so actually, I wasn’t to bad/far off initally, quite good really fair play to me, he he.

      • In my view, the word “invention” in firearms business is highly questionable. What are we trying to invent? The spade? Every detail in this notoriously mechanical set of solutions is known and attempted or even tried and made on a mass scale. It is all about basics, combined in some convenient way.

        When I follow my early path I can only say I was “inventing” because I did not know what was attempted before. But that is the common path to discovery – it makes one aware and expands his horizon. It accelerates the knowledge, but it also leads to a cruel awakening – it had been done before.

        Where some help comes from is manufacturing techniques; therefor what was deemed once difficult may be made easier now. Can you patent a manufacturing method? Of course you can.

        • Fair point, well made. You can indeed. But… No. It hasn’t “All” been done, not everything. Combine the two… Method, A bomb pressed spoons; nobody has a monopoly on the atom, bar god.

          Amen, he he.

          • “No. It hasn’t “All” been done, not everything.”
            you are giving me some hope 🙂

            Yes, I have one of those “never done before”. The next thing is to score a sale…. make someone believe they can make buck on it while screwing me. Oh boy!

          • In Walden, the Author says “he concentrated on, not needing to make folks buy them; goods of such…” Was on about a Indian basket weaver, dude. Who made good baskets, but the folks with cash at that point had baskets so it left him kinda fucked. So he went eating berries to survive.

            He he, I mean it’s different. “If I sound cynical there, I sort of don’t mean to be.” Because! He had the most amazing time, watching birds go about there buisness and he was just sat there watching for years.

            Thats enough for any mans life, surely; to see truely what everything else is doing, wee birds, slugs, ants , fish etc.

            He he, fair play.

        • I bought a ebook about calculus and algebra… And fair play to anyone who gets that. Probably should try and read them, as oppose looking at “nudes” on the internet, he he. Internet eh… What a world, I remember having a “real” game of Soldiers; vs a ps game, which was dangerous… Shot at each other “pellets, catapults” fireworks… Bricks. Other things involving gunpowder periodically, didn’t shoot any captives. Everyone went home “albeit a few had minor injuries” out of about 35.Didn’t gain an Iron Cross personally, but I shot a few fuckers in the ass with a hw35 and never got caught by the other team.

          • Children were sensible then, I waited for an opportune shot in the ass untill they were 40 yrds plus; point was to let them know “they were dead” in said war game. Didn’t pierce any flesh, just stung.

          • Proper Nam, full Camo on; Hw35 my friends Dad gave me “I was the best shot, over his Son” he organised the War, hee… Times change, full submersed in cow pat infused streams, flies, the lot crawling slowly, hours; Bang!!! Well, pop… Two sore arses.

            Times change; personally I think we have lost something.

          • His Son Oliver” did get the “Iron Cross mind” to be fair he deserved it; frontal assualts, after brick shelling; I crawled back for orders and it was fair brutal. Slunk off again in the mud; with the best gun, Ziess sight 4×35.

          • Well I suppose your not losing something as a society, if you don’t want folk to join the Army; but at the time it was still in “fashion” times change, he he.

    • Does anyone know enough about Nitinol to say that couldn’t work: “You can be cruel, to be kind.” That would be, fine. If the bolt is exerting such a pressure (mass mainly- Spring is extended) I read that Niti doesn’t like to be constrained “and in this scenario, it is I.e. The bolt is up against the case as per, the Niti to change shape must push the against the bolt, as the barrell is fixed.

      How much Niti/temp etc is required? Science folk. For a jolt of 5mm, but importantly a jolt.

      • If a 4mm thick band of Niti can fold “due to the design of the case; don’t worry about the format, rebated rim etc” but, if it must bend 100,000 psi etc. Will that move a 5 pound even, bolt with a spring against it 5mm?

      • Coneheads… “Just ate some nachos” aye… So. 7.62x51mm case, yes. Ends in a < cone "quite" sooo… You have a Niti "spacer" yes… Looks like a spacer. Now! The rear of the case has a primer rim (rimless rim) etc. But its formed over ze cone. 2 seperate parts. YES. Ok, so… So. So! The rear of the case, is normal at the rear (Aye normal) but its front looks like a drill… Front "adjustable thing you put drill bits in" Indeed. THUS…You put a Niti band around the rear part "via grooves" and you put lips on the cones end, which correspond with teeth on the rear portion… Bang! Heat compresses niti band around outer drill bit; said bit, forces outer to compress, around inner (burp, its along these lines; remember my Ar Niti bolt) and… Er, the rear portion operates the action "Francis type" case stays together, ejects.

  10. The chamber/barrel is hot for Niti… But maybe, you could use the bending of the “spacer” to ignite the cartridge also… Less good for semi auto he he… But in essence, you put the primer in a different position; forward of now… Spacer bends; pushes back against the bolt, but it also in so doing snaps the primer, rimfire… Needlefire lark. “Tweet” Some problems, meh all good; fiddle. Draw action with pencil, for better understanding he he.

    Mini gun with no firing pin, this type of locking mech, electric operation; heat, to start the reaction. Gun fires till it runs out of rounds… Some uses, perhaps… Planes.

    • Or maybe… “Troops” think the tank buster, if in the future “troops” are in heavy armour “think terminators” well the tank buster works by the number of hits… Albeit of heavy rounds. But the same logic must apply, to defeat heavy “troop” armour; 250rnd mini gun of at least 7.62x39mm Defeats simply by volume of fire: Yes a lot.

      • T3 film, the robot (with the mini gun arms) “dies” as Arnie hits it with one of its mates mini guns; volume of fire, it simply couldn’t take that type of battering albeit it was made from out of metal. They’ll be a limit how heavy something that size can be armoured even for robots.

          • If we ever needed too… And we might not, but it is worth thinking about; no pensions needed for robot soldiers so you can bet somebody is trying to make them. Some thick person, who simply can’t get that they will totally become a new life form and turn on our sorry arses.

          • Yes you’d need a bipod he he, splat it with a piat type thing; then keep its head down so to speak, volume of fire; piat again; reload.

            Much better with 30 folks hitting it thus, than with AR’s. As it will fire back.

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