Pedersen Selfloading Rifle at RIA

When the US military decided to seriously look at replacing the 1903 Springfield with a semiautomatic service rifle, two designers showed themselves to have the potential to design an effective and practical rifle. One was John Garand, and the other was John Pedersen. Pedersen was an experienced and well-respected gun designer, with previous work including the WWI “Pedersen Device” that converted a 1903 into a pistol-caliber semiauto carbine and the Remington Model 51 pistol, among others.

Pedersen’s rifle concept used a toggle locking mechanism similar in concept to the Borchardt and Luger pistols, but designed to handle the much higher pressure of a rifle cartridge. Specifically, the .276 Pedersen cartridge, which pushed a 125 grain bullet at about 2700 fps. Both Pedersen’s rifle and the contemporary prototypes of the Garand rifle used 10-round en bloc clips of this ammunition. Ultimately, Pedersen lost out to Garand. Among the major reasons why was that his toggle action was really a delayed blowback mechanism, and required lubricated cartridges to operate reliably. Pedersen developed a hard, thin wax coating process for his cartridge cases which worked well and was not prone to the problems of other oil-based cartridge lubricating systems, but Ordnance officers still disliked the requirement. This combined with other factors led to the adoption of the Garand rifle. After losing out in US military trials, Pedersen still had significant world-wide interest in his rifle, and the Vickers company in England tooled up to produce them in hopes of garnering contracts with one or more other military forces. About 250 rifles were made by Vickers, but they failed to win any contracts and production ceased – making them extremely rare weapons today.

Pedersen lived until 1951, and was well regarded for his sporting arms development with Remington – none other than John Moses Browning described him as “the greatest gun designer in the world”.


  1. I wonder if a fluted chamber would have allowed the Pedersen rifle to extract reliably without lubricating the cartridges? It seems to work fine for the HK roller-delayed blowback rifles, but it did not work well enough in the FIAT-Revelli Mod. 35 machine gun.

    I would also disagree with Ian a little about the integral cartridge oilers: the Schwarzlose M07 MG seems to have worked just fine. The Breda Mod. 37 machine guns also worked well enough. Some sources claim it had problems in the dusty desert environment, and logically there must have been some, but the Italian sources I have read still consider the gun reliable enough and do not make a big deal out of the lubricated cartridge requirement. (Unlike the FIAT Mod. 35, which lacked the integrated oiler and required manually pre-lubricated cartridges, a real PITA in dusty environments. Some sources mention that the some Mod. 35 machine guns were re-fitted with a cartridge oiler, but that must have been an unofficial field modification, since it’s not mentioned in any primary sources.)

    • The Schwarzlose M07 worked as a delayed blowback, but only because it had a short barrel. This was deliberate, to keep MV and breech pressures down to levels that could be handled by a heavy recoil spring. Its characteristic long conical flash hider was to compensate for the terrific muzzle flash that occurred with every shot due to still-unburned powder “flaring” on contact with the open air.

      It would certainly have benefited from a fluted chamber. So would most blowback, delayed blowback, or similar systems firing full-power rifle ammunition.

      The exception being the .30 Kimball pistol, firing .30 USC; it needed its “gritted” chamber to keep the bolt from opening too quickly. Especially because the only thing keeping the bolt from coming off the rear of the frame in the shooter’s face was a pair of bolt stop lugs at the very rear of the frame.

      It is rare to find a Kimball today that doesn’t have at least one broken-off stop lug. Of course, Kimballs are rare, anyway, and this is one big reason why.



    • Fluted chambers were not all created equal.

      Depending on the dimensions of the flutes, you can control the gas pressure outside the case – but at the cost of heating the chamber and slight losses from propelling the bullet down the bore.

      Case lube simply provides a layer with very low shear strength between the case and the chamber – and because that lube is almost incompressible it almost completely equals the internal pressure of the case – for most of its length – naturally there is a pressure gradient at the entrance of the chamber where the lube tries to squirt out.

      There is a similar pressure gradient at the entrance to a fluted chamber too, and a lesser gradient allong the flutes, as gas takes time to flow into them, and it looses pressure as it flows, due to both expansion and due to heat loss to the chamber walls as it flows down the flutes.

      Problems with the Fiat Ravelli 35 probably reflect engineering details rather than the concept of fluting per se.

      • “the cost of heating the chamber and slight losses from propelling the bullet down the bore.”
        The Russian ShKAS machine gun has fluted chamber (also known as a “Revelli grooves” as it was firstly used in Revelli machine-gun) and the difference in muzzle velocity is neglible, muzzle velocities for:
        7.62 cartridge PZ
        ShKAS: 800…815 m/s
        Rifle Model 1891/30 [Mosin]: 820…835 m/s
        7.62 cartridge B-32
        ShKAS: 810…825 m/s
        Rifle Model 1891/30: 860…875 m/s
        I assume that the slight difference is caused by this that part of energy was used to cycle the ShKAS machine gun rather than the fluting of cylinders.

      • You are probably right about the Mod. 35. It fired from a closed bolt, which was already a recipe for problems with the powerful 8x59mm RB cartridge. Additional heating of the chamber because of the flutes must have made the problem more serious, especially at higher rates of fire. This conundrum probably have influenced the engineering of the chamber, but apparently no satisfactory solution was found. Consequently, a “decelerator” for selectable rate of fire had to be installed. The maximum 600 rpm could be used only for short bursts or ammo cook-off was inevitable, especially in the summer.

  2. According to Barnes, the .276 Pedersen normally fired a 120-grain @ 2550 FPS for 1730 FPE, or a 150-grain @ 2360 for 1858. I suspect the latter was intended as a machine-gun round, in keeping with the policy of chambering the rifle and support MG for the same ammunition.

    There are few strictly comparable rounds, ballistically speaking. The .276 Enfield is more powerful, with a 165-grain @2800 for 2880. (Incidentally, contrary to what some have said, the two cartridges are not the same, in fact they aren’t even close, as the Enfield is a rimmed cartridge similar to the Canadian .280 Ross.) The 7×57 Mauser is more powerful, as is the modern 7mm-08 Remington.

    The closest ballistic “twin” to the .276 Pedersen is the Italian 7.35 Mannlicher-Carcano. Among purely sporting rounds, the 7-30 Waters is very close to the .276 P, as it generally uses 120-grain bullets at around 2700 for 1900 FPE.

    I’m wondering if Pedersen wasn’t thinking in terms of what would be known as an “intermediate” cartridge a decade later. The .276 P certainly fits the parameters, being lighter, accurate out to 400 meters or so, and generating reduced recoil to allow controlled rapid fire or possibly full-auto fire at short range from the shoulder.

    This might also explain why the rifle’s action is so finely balanced for that power level. It’s possible Pedersen didn’t want Ordnance trying to turn his “intermediate” rifle/cartridge system into a “traditional” long-range rifle with all the attendant perceived drawbacks on an actual battlefield.

    All I can say is, an “original” pattern Garand in .276, with a 20 or 25-round detachable box magazine, would be highly interesting. Especially with a fire-selector switch similar to the later M-14.

    Certainly, a “modern” Garand or M-14 could be made in this caliber, but since they are basically .30-06/.308 rifles their greater dimensions and mass would seem to negate the potential advantages of the .276 concept.

    Hm. Now, a Ruger Mini-14 or Mini-Thirty in .276 would be a different story. (Mini-14 in 6.8 SPC, perhaps?)



    • “The .276 P certainly fits the parameters, being lighter, accurate out to 400 meters or so, and generating reduced recoil to allow controlled rapid fire or possibly full-auto fire at short range from the shoulder.”
      Pedersen designed the Remington Model 14 before WW1 which was chambered in .25 Remington Auto-Loading, .30 Remington, .32 Remington and .35 Remington. The first three are very similar to later intermediate cartridge in term of ballistic – compare the .30 Remington to 7.62×39. So this maybe a source of Pedersen’s idea of “not-full-power” cartridge

      “This might also explain why the rifle’s action is so finely balanced for that power level.”
      For me, the Pedersen firearm was designed with “not being too burly for cartridge” in the mind – Remington Model 17 (co-designed with J.M.Browning) was 20-gauge ONLY shotgun unlike contemporary 20-gauge shotgun which often were slightly altered 12-gauge guns, Remington Model 25 was chambered only for 32-20 and 25-20 unlike the competitor rifle – Winchester Model 1892 which was designed for 44-40 or 38-40 and later altered to 32-20. This mean that fate of each firearms was tightly tied with fate of its cartridge, as .276 Pedersen fail to enter service the rifle also consistently fail.

      • I don’t know, but military rifle sights of the era tended to be over-optimistic as to maximum effective range.

        Using the online ballistics calculator found here;

        And assuming a Barnes 120 grain BT (closest thing to the military load in their lists), I got these trajectory results assuming the standard MV of 2550 FPS and a 100-yard zero;

        Range Drop
        (yd) (in)
        0 -1.5
        100 -0.0
        200 -4.8
        300 -17.0
        400 -38.2
        500 -70.2
        600 -115.1
        700 -175.8
        800 -255.5
        900 -357.9
        1000 -487.1

        So while the rifle might be sighted to 1000 yards, the chances of hitting anything much beyond 400 wouldn’t be anything you’d want to bet the ranch on.

        BTW, remaining energy at 400 would be 864 FPE, at 1000, 303 FPE. So it would still kill at 1000- assuming you could hold over 40 feet and 7 inches. (Energy at 400 is about 90 FPE less than ME of .30 USC with 110-gr FMJ service load.)

        I’d say it fits very well into the “intermediate” category, albeit with a bit more “oomph” at all practical ranges than the 7.62×39 or 5.56×45. The .280 British (EM2) with 139 gr @ 2530 would probably be in the same ballpark as the .276 Pedersen in KE terms at most ranges.



        • The overly optimistic sights of the era were vestiges of the pre-WW1 volley fire tactics. While WW1 had shown that rifle volley fire could not be utilized effectively any more, it took armies (and gun designers) some time to bring that realization to the rifle designs. Sometimes they then went too far like with the 7.35mm Carcano rifles, which had sights fixed at 200 meters.

        • With the postulated trajectory, if it had a “battlesight” setting like the AK or SKS (that “D” at the bottom of the slider), or for that matter with the sight set at 100m, at any range under 300m if you shot center chest on an enemy soldier, the bullet would hit somewhere on a vertical line between the shirt collar and the belt buckle.

          Which for practical military purposes is all that’s required.



    • For a little while Ruger offered the Mini in 6.8 SPC–t sure that they were using the revised dimensions for the chamber, and may have hurt sales before they were discontinued.

  3. The .276” cartridge was lubed with a dry wax much like car wax. It does not feel oily or pick up grit. Some in Ordnance liked the wax because it also protected from corrosion.

    • Pederen’s patent for lube is available (I’m not near the computer with my copy of it), IIRC it actually did use a car wax. There are several later patents for case and bullet lubes which use synthetic waxes (usually used for car polish) and various plastics, eg poly ethylene (can’t remember what density).

      • The Pedersen patent is US Patent 1678162A, available here:
        Pedersen notice that this not only ease extraction but also such coated cartridges can be storaged longer. Pedersen directly write of “solution of ceresin in carbon tetrachloride, the concentration of said solution being approximately 7% ceresin at a temperature. of said solution of approximately 50 C.”;
        the patent drawing is NOT to scale, as stated in text: “the drawing necessarily exaggerates the thickness of said Wax coating (…) In actual practice, the coating is less than a thousandth of an inch thick”

  4. Well its a remarkable conception, a toggle action without the barrel moving. Nothing actuating it other than pressure against the bolt, from the cartridge blowing back, does a bit not even move first then “stop” while the other bits continue moving – collecting the part which stopped later as in the pistol sort of… Has it just been worked out exactly what resistance it would take to break a toggle, of a certain weight, shape etc, slow enough for it to work.

    Its an incredibly beautiful rifle, I would want that, and look at that amazing British machining, we couldn’t make that these days.

    • There might be like, a series of folds, overlapping… Bits which cover over bits while they are all moving, but they can’t all move as much as they would like, until certain bits have moved to certain points or something.

      It’s certainly novel, the no mechanism action sort of thing, it just does it, there is but not, kind of reminds me of a snake.

  5. “Among the major reasons why was that his toggle action was really a delayed blowback mechanism, and required lubricated cartridges to operate reliably.”
    This must be noted that any will hesitate against any new cartridge, so even if the .276 Pedersen wouldn’t need wax-coat it could be rejected, for reason of different cartridge for rifle and for machine-gun.

    • Anyway US Army ended with 3 different basic infantry cartridges: .30 Carbine, .30-06 for M1 Garand and .45 Auto for automatic pistols and sub-machine gun. I suspect that if the .276 Pedersen would enter service the .30 Carbine wouldn’t been needed – the .276 Pedersen would allow to make lighter carbine version of rifle that .30-06.

  6. IIRC several Pedersen rifles have been brought back from occupied Japan (3, I believe, with two having mismatched bolts that were numbered to each other). Had Japan produced and issued those in quantity, it might have proven an effective counter to the Garand on a number of levels, including a cartridge that may have been better protected against tropical humidity. The biggest problem I see with the rifle, from a shooter’s perspective, is having the toggle rising up and breaking the line of sight with each shot. It might induce a flinch or blink in some shooters, and would definitely take a bit of practice to get used to. I know that when I first started shooting Lugers, my focus would briefly shift to the toggle and cause me to have to re-focus my sight picture. With a rifle, it would probably be more of an issue. (not sure if this was mentioned in the video, as the sound is bad on this computer)

  7. Basic principle of Pedersen toggle using delayed action generally is stated nearly as enchanted. A powerfull rifle cartridge is used through a toggle action very similar to Borchardt lock but with absence of carrying the center joint below the line of front and rear’s. In fact, the secret of action lies ingeniously using two front joint with the center joint being held all the time over the front and rear joints. There are two front supporting joints behind the breechblock as bottom one being in contact with that part and upper one being slightly rear at vertical plane. When the recoiling begins, breechblock pushes the toggle action rearward from the bottom joint causing the middle joint to rise up slightly as rotating the front arm forwards and as forwarding the upper supporting joint to get contact with recoiling breechbolt but, drawing the bottom joint out of contact with same. During this well calculated small backward travel, most of the high chamber pressure drops but middle joint remains nearly at the same situation when the recoiling started by means of double front supporting joints working in stated sequence. Remaining harmless gas pressure and gained mmomentum push the toggle action rearward starting at the similar break up position with the initial motion.

  8. One objection to the Pederson rifle cited at the time was that the toggle could smack the rim of a soldier’s helmet. Certainly it jumped pretty high, and violently. Firing from the hip or other non-shouldered stance required taking notice. The cartridge didn’t stand much chance of adoption either, with WW2 clearly coming; MacArthur was quite right that it was not the time to introduce a new rifle/MG round.

    • When MacArthur rejected the .276 cartridge the US was short several million rifles and didn’t have the factories in place to produce them. Also, the US didn’t have the factories to produce the needed 30/06 ammo nor the forth coming M1 carbine ammo.The factories had to be built to make all of it.

      Would have been the perfect time to introduce a new cartridge. The US might have never have needed to adapted the .30 Carbine, .308 nor the 5.56. And 2 of these were adapted during war time.

      But suppose adapting a new cartridge is like going to jail. There is never a convenient time for either.

      • You also have to remember that the decision was made during the Great Depression, when Army funding was very limited and in was uncertain how long the Army would have to get by on a very tight budget. Under those circumstances, MacArthur’s decision must be considered defensible.

    • Hitler was appointed Reichskanzler on January 30th, 1933 and his power was cemented by the Enabling Act in March 1933. So, in 1932 when General MacArthur made his “suggestion”, WW2 was not on the table yet. However, the Great Depression was very much still ongoing and the associated budget cuts were probably his primary motivation.

      • It seems to me that the Great Depression would’ve been an ideal time to make the change. So many out-of-work Americans could’ve been given factory jobs making the rifles and ammunition.

        • Yes, if you believe in Keynesian economics. F. D. Roosevelt, who was a kind of proto-Keynesian, however did not become the President of the US until March 1933. Although his predecessor, president Hoover, already initialized many relieve programs, they did not extend to military spending. (And neither did Roosevelt’s initiatives before a new war in Europe started to look likely a few years later, and even then he had to balance with the powerful isolationists.)

          • Indeed, Hoover was brought up Quaker (religious pacifist).

            However Hoover’s commitment to proto Keynesian “stimulus”* for every area but the military was later quietly aknowledged by the FDR camp – his regime was far from the champion of laisez faire which FDR’s court chroniclers portrayed it as during the election campaign.

            *rewarding cronies at everyone else’s expense

  9. strongarm & gunsmith’s kid;

    The Swiss Furrer-designed Model 25 LMG and Model 41 SMG both use a toggle action on the same principle as the Parabellum. But they “break” the toggle horizontally to the left (both feed from horizontal box magazines on the right side).

    I suspect this was motivated mainly by the desire not to have a long magazine sticking down which would be a problem when firing prone (see; Mkb42/MP-43/STG-44). But it also kept the shooter from feeling like he was going to get hit in the nose by the toggle with every shot, as well.



    • Using toggle lock in auto loading shoulder firearms is nearly as old as the section of the class itself. Hiram Maxim, John Browning and German Carl Hillman had shotgun patents at beginning of the 20th. Century. But truly working samples in shotgun section were made by Walther and DWM between 1922-1933. They were short recoiling toggle lock guns including all joints inside the receiver and in downwardly working order. An outside horizontal to downside rotatable arm was used to open the action manualy. American Patent numbers; 1457477 and 1481042 and Ian may offer a study covering them in the future.

      • The toggle lock supposedly goes back to a long forgotten gunsmith in Italy. Maxim came to it via the Volcanic, Henry and Winchester lever actions.

  10. 276 m 1 were made for testing. 276 m1 weighted 6 lb vs 8 for 30 cal, magazine for 276 held 10 rounds vs 8 for 30 cal. The 276 was a shorter rifle so the m1 carbine may not have been needed.

  11. I remember seeing Vickers-Pedersons at UK arms fairs some years ago. No-one seemed particularly interested, because of the odd calibre I suppose – and you could get a regulated No.4 for a tenner. Wish I’d payed more attention (and the few quid asked!)

  12. McBride (A Rifleman Went to War) suggested .27 caliber as being the ideal mix of portability and lethality after WWI, so the idea of going to a smaller cartridge had been floating around for a while.

    It is strange how the .27 / .276 / 6.8mm shows up every few decades, appears to be the answer to the problems of the day, and is turned down because, well, there is something else around already. If only one of them would have been an exciting new space-age cartridge when Sec of Defense McNamara decided what cartridge the US military would be using for the next half century.

    Pederson also designed the Remington model 12, a slick little slide action 22 caliber rifle. Even an ancient one opens locks up solid. I’d really like to get one and have the barrel relined, it is just a slick design. I think that some of his designs, though, were maybe overly complex and not exactly easy to make or repair (e.g., the Remington model 10 shotgun).

    • “Remington model 10 shotgun”
      It was designed in this way because J.M.Browning patent cover crucial mechanism for side ejection (it would become Winchester Model 1897 IIRC), so the Pedersen designed firearm with downward ejection. Concerning the limitation of non infringing before-mentioned patent claims the Pedersen firearm when not easy to repair at least work properly (unlike St. Etienne “NOTHotchkiss” Mle 1907 machine gun). Remember that ability to work inside limitations is sign of genius.

  13. Is it sort of a 1913 Webley, but instead of the barrel going down its something within the bolt? Russian chaps, with somewhat broken English, would you mind explaining again there’s a good fellow.

  14. It seems the barrel has some unusual spiraled flutes or machining to dissipate heat. Is this unique to this gun? Any comments? What advantage can spirals have over rings, which I assume must be easier to machine? I must say one can see the whole piece was made by professionals.

    • Those spiral ribs are standard on the Pedersen, cut to aid cooling. I expect the spiral was chosen over rings because the whole thing can be cut in a single operation, instead of having to reset the cutter for each ring.

  15. I just happened to be re-reading Julian Hatcher’s Book of the Garand when this blog entry popped up. According to Hatcher, the Pederson round was tested with both 125 gr and 140 gr bullets with the decision to stay with the 125 gr bullet. The shoulder fired semi auto rifle requirements set forth for what became the M1 (and which the Pederson was designed for) was an effective range of 600 yards. The Goat Board and Pig Board tests showed the 276 round to perform better than the 30 cal in wounding potential out to 600 yards ( the 256 round that was tested performed best out to 400). Of course, all three were very lethal and nobody would want to be hit by any of those bullets!

    I would think the toggle link would be a bit clunky when firing but none of the test personnel commented negatively on this. They did comment that the toggle would often strike the hat and there was concern about this when firing prone.

    I have to agree with what others have already stated – had the 276 cartridge been adopted in either the Pederson or the Garand, I doubt the M1 carbine would have ever come about.

  16. I should add – as Ian points out in his video regarding the high tolerance machine work in the action… US Ordnance testers marked the manufacturability and parts count against the Pederson and found the Garand superior. They stated that the Garand would be simpler to manufacture for interchangeability than the Pederson which they felt would be problematic and more costly. These were critical aspects when you consider they made millions of Garands during the war.

    Nevertheless, it is an interesting alternative history to think about had the 276 cartridge been adopted in 1932. We may never have had the 762 NATO or even the 556….

  17. My question may seem off-the point. However, what interests me in connection with Pedersen is the device that he supposedly developed for converting non-automatic rifles to self-loading/fully automatic. I read about it in one of the general histories of firearms – there was an illustration (hardly self-explanatory), but in no way was it explained, how it worked. Is the present example related to it, or totally unrelated? Can anyone help me?
    Thanks and regards, Andrzej

    • Actually, Andrzej, I have some video of a Pedersen Device in use that I will be posting shortly. Basically, it was a drop-in plain blowback bolt in a small .30-cal pistol cartridge, for use in the 1903 Springfield (experimental versions were also made for a couple other rifles).

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