1. Rocket pistol is interesting idea, but how would it be treated in light of international war law? The bullet contain the powder so do it can be treated as a HE bullets for rifles and therefore prohibited due to Saint Petersburg Declaration of 1868?

    • Even though the projectile contains the propellant, it does not explode on contact, even against a hardened steel plate, let alone flesh. Therefore, it is not illegal under any of the “Conventions” of war.
      On a more interesting point, it is about as accurate as a specific shot gun pellet in any load of buckshot with out the other 14 pellets of 00. To say it had accuracy problems is a gross understatement. It also required some distance to get up to speed and have any destructive power at all! It would not perforate a sheet of cardboard from a cereal box with the muzzle in contact with that box. The spinning projectile would give your hand a friction burn, but no bruise, held against the muzzle, then bounce harmlessly along the ground till it burned out.
      As an aside, after they had been around a while, you could buy them for less than a hundred bucks, if you could find them. That is how I got to shoot one that belonged to a friend. He sold it for $35 when his first two boxes of ammo was gone.

    • A more immediate problem was that the original 13mm Gyrojet, like the one Ian showed, was classified as a Class III “destructive device” under GCA ’68 because its bore was greater than .5 inch (12.7mm). Later Gyrojets were 12mm bore to get around this problem. (I don’t believe the size of the ammunition ever actually changed, just the “official” bore spec.)

      I believe all of the above are classified as “curio or relic” today mainly due to the fact that they do not use conventional cased ammunition, and cannot be modified to do so in any practical way.



  2. Tim Bixler registered one of the rifles as a machine gun. Not sure how the mechanism was modified to be full auto but I assume it had to have another trip in the barrel so that as the round passed over it the hammer was released if the trigger was still being held down.

    • If the internals look anything like the original patent drawing


      All that would be necessary would be a vertically-sliding “tab” above the trigger that locked out the disconnector slide. With that locked, the hammer would spring up and back after being over-run by the departing rocket projectile without any additional help.

      Mind you, I doubt it would fire a lot faster in rounds-per-minute than you could fire it by just pulling the trigger for each shot. IIRC, one of the big problems with the Gyrojet was the “dwell time”, as the initially slow acceleration of the rocket meant it took its own sweet time clearing the launcher. Which did nothing to improve its already below-average accuracy.



    • MBA did try to sell it to the Defense Department, but as a weapon for the Navy’s SEALs. It will work underwater, and while range wasn’t impressive (max effective was about forty feet, IIRC), it was still better than a knife fight with an enemy diver, and was more compact than a conventional spear gun.

      BTW, the SEALS recently were using Glock 19 automatics in 9 x 19mm with special “underwater” firing pins that have flutes machined into them, rather like those in the firing pin of a P.08 Parabellum. The flutes allow water to flow past the firing pin in its “tunnel”, so as not to slow it down and reduce the force of its strike on the primer.

      With little tricks like this, conventional pistols work perfectly well under water. Their bullets will still retain enough velocity vs. water resistance to be deadly with center-torso hits out to about 20 to 25 yards.

      Which is actually about as far as a typical rubber-powered spear gun will do the job, as well.



  3. Rockets that are not “all burnt” within the launcher have an inherent accuracy problem simply due to being rockets. When a conventional bullet exits the barrel, it will wobble on its axis a bit in flight. However, since it is simply following a ballistic path, that wobble has a fairly small effect on its trajectory (simply those due to aerodynamic effects).

    If a rocket is still burning after it leaves the barrel however, that wobble will have a different effect. The wobble causes the rocket exhaust to point in slightly different directions, pushing the rocket off trajectory. The “wobble” will be self correcting to some degree (as the exhaust successively points in various directions), but the end result tends to be rather random.

    On a slightly different note, the acceleration of a simple rocket will typically increase as it goes along for two reasons. One reason is that the rocket is becoming lighter as the fuel burns, so there is less mass to accelerate. The other reason is that depending upon the shape of the fuel (which is usually a solid, rather than loose grains), the area of the burning surface may increase as the fuel burns. The reasons for the latter are a bit complicated, and may not apply in this case. However, the variables involved in this may result in an inconsistent “burn-out” velocity and so a slightly different ballistic path.

    Even modern artillery rockets (e.g. Russian “Grad”) are generally less accurate and consistent than “tube” artillery. Their main advantage is in carrying a larger payload (because the launch forces are lower than being fired from a gun) and you can fire large salvos quickly over an area (using a multiple-launch system). In those applications having a larger “group” is not a disadvantage.

    Trying to miniaturize something like a rocket down to pistol or rifle size just isn’t practical with the technology that we have today. The fascinating thing about the Gyrojet is that they managed to make something that worked at all.

    • In most respects, the Gyrojet “ammunition” (you can’t really call it a “cartridge”)was a scaled-down Hale rocket;


      Note the patent date; 1866. And this was a late version; Hale’s earliest patent dates to 1854.

      Hale rockets were (briefly) used by the Union forces in the first years of the American Civil War, but by 1863 the rocket batteries were re-equipped with either 12-pounder mountain howitzers or the heavier 12-pounder M1858 “Napoleons”.

      The major complaint everyone had with the rockets was their poor accuracy and erratic flight characteristics. Not to mention their occasional trick of hitting the ground short of the target, taking a wild bounce, and coming back at the FLOT, sometimes straight back at the rocket battery which had fired them.

      The Gyrojet showed no discernible improvement even after a century.

      BTW, in artillery terms, a “grouping” 6 feet (2 yards) across at 100 yards equals a dispersion of 20 mils (1 mil= 1 yard “off” point of aim at 1000 yards range). This would be defined as “inferior” dispersion for a spin-stabilized bombardment rocket like the WW 2 4.5 inch, which had a standardized dispersion of 16.6 mils. (Ley, Rockets, Missiles, and Space Travel, Viking Press, 1954 ed., p. 185.)

      In short, the Gyrojet pistol shot demonstrably worse than a T-34 4.5in Calliope;


      And in a fight, it only had six shots to the Calliope’s sixty, and once it was empty you wouldn’t have had a Sherman to “back it up”.




    • “Trying to miniaturize something like a rocket down to pistol or rifle size just isn’t practical with the technology that we have today.”
      Do you think that recoilless handgun is feasible with modern technology? During WW2 in Britain was developed recoilless rifle – Broadway Trust Rifle also called Burney rifle after inventor or EM-4 rifle.
      It uses “.27 Broadway Trust” cartridge so it was similar to rifle caliber, unlike American M18 Recoilless Rifle, but can be it be scaled down even more to fit handgun size and be safely used with say 2 nozzles – one 135 deg. left to barrel and one 135 deg. right to barrel? Using recoilless can eliminate accuracy problems of rocket propelled design.

      • Any RCL small arm is going to have the problem that the efflux is going to come near the shooter or someone next to him, with dangerous consequences.

        Aiming the effluxes at 4:30 and 7:30 just makes them extra-dangerous to the rest of the firing line and anyone walking behind it, all at the same time. That gas is hot, and has mass and velocity, and if it hits you it will at least burn you, and could easily kill you.

        Burney’s first experiments were with a 10-bore double shotgun with an exhaust tube that led back over his shoulder. Standing anywhere within ten feet of that one in back of the shooter was hazardous.

        Harry Harrison’s SF novels to the contrary, a recoilless handgun or rifle, while technically possible, can never be safe for anyone on your own side. Physics is unforgiving.



  4. I’m surprised that nobody’s made replicas and ammo just as an expensive novelty…

    (And these days, following in DARPA’s footsteps, I bet you could make them laser-guided to within enough margin to make them quite accurate … at a cost that’s completely untenable per shot.)

    • According to John Walter in his books on German small arms of WW2, the HWA had Geco and BASF develop rocket projectiles like the Gyrojet during the war, in 8mm, 9mm, and 11mm persuasions. Exactly why is obscure; some sources claim the 11mm was intended for a very high-rate-of-fire low-level anti-aircraft weapon along the lines of the 2cm Fliegerfaust;


      The 11mm version might have been intended for a “roman candle” type load, rather like the more recent MetalStorm concept.

      As for the 8mm, it was apparently intended as an assassination weapon, that could be concealed in something innocuous and fire a poisoned projectile into the hapless target without leaving incriminating cartridge cases, etc., behind. (They also worked on caseless ammunition in 7.65mm for the same purpose.)

      I suspect these “brainstorms” may have been the origin of the “cigarette rocket” in the James Bond movie You Only Live Twice (1967), which of course also featured both Gyrojet pistols and carbines in the hands of the heroes.



  5. I always think that this system could be developed. Hammer spring could be made more
    stronger for better dwell time and if the user easiness were the case, a simple leverage could be arranged to cock the action.

  6. I know of the location of a MBA Gyrojet 13 mm pistol that is for sale.
    This is THE prototype and bears the Serial number of B000.
    Could you estimate what the sale price should be ?
    Would RIA be interested in buying it ?

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