Chinese QX-04 Rifling Delayed Blowback Pistol

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Here’s an interesting weapon from Chinese firearms designers (courtesy of Armory Exotic, an excellent blog) – at first it appears to be a pretty mundane-looking handgun, but a closer look reveals a pretty unique operating mechanism:

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The QX-04 pistol, showing its spiral fluted barrel, which is central to its unique operating mechanism. Image source: raigap.livejournal.com

The barrel is spiral-fluted in the opposite direction of the rifling in the barrel. When a bullet is fired through a rifled barrel, it exerts tremendous pressure in the direction of the rifling’s rotation, as the bullet is squeezed and spun under incredible acceleration. In the QX-04, the barrel is locked against surfaces towards the front of the spiral grooves. When the cartridge is fired, the slide wants to move rearward, but it cannot do so against the grooves in the barrel. The bullet, while it is in the barrel, is torquing the barrel in the opposite direction of the spiral grooves, preventing rotation of the barrel and therefore locking the slide against the angled surfaces of the spiral. When the bullet leaves the barrel, the rotational force on it is dramatically reduced, and the slide can rotate the barrel to unlock, through residual gas pressure. Clever, isn’t it?

With this operating mechanism, Chinese designers have created handgun variants in four calibers, the Chinese traditional favorites 9×19, .45 ACP, and 7.62×25 Tokarev, and the Western relative newcomer .40 S&W.

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Four barrels alongside a QX-04 pistol. Notice the long, spiralled grooves, and lack of a flat rotary locking surface. Image source: raigap.livejournal.com.

Some readers may recognize the description of the action as being very similar to the old Savage 1907 automatic handgun. While this is true, the QX-04 seems to take it further, by having four huge cam tracks running more than half the length of the barrel.

There’s some doubt as to the exact physics of how this handgun works, as it’s unclear that the bullet is able to actually lock the slide against the inclined surface. It’s possible the spiralled grooves actually act more like the inclined surfaces in a roller- or lever-retarded blowback weapon. If the weapon actually locks in the initial stages of firing, then it could qualify as a delayed blowback weapon, but if not it would be technically defined as a retarded-blowback design. The distinction between the two isn’t discussed much in small arms, but comes up much more frequently in the discussion of autocannons. More details on the subject are available in Chinn’s The Machine Gun. 

H/T, Alexander of Armory Exotic.



Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He can be reached via email at nathaniel.f@staff.thefirearmblog.com.


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  • tazman66gt

    Rilfling?

    • Mystick

      Indeed. I have never heard that term.

    • Good catch!

    • El Duderino

      RILF = Rifle I’d Like to Fire.

  • Tom

    As I understand it this system did not work terrible well in the .45 Savage and resulted in heavy recoil however this does seems a little more involved.

    Whilst its great to see innovation in any field I can not help but think that JMB came up with the best solution back in the early 20th century and I can not see any advantage to this system.

    • Mystick

      More nooks and crannies to get dirtied up, inhibiting operation.

  • MountainKelly

    as the rifling gives out due to stress over time you’d see less force applied to it by bullets and a reduction in the system’s ability to cycle the action…

    is meh. Theoretically neat, practically? I think it’d be a fun proof of theory model but that’s about it

    • MP

      No. Wear would have no impact on forces applied until such a point that the bullet rotated separately from the barrel, which would require the rifling to be almost entirely gone. At that same point in it’s service life it would lose accuracy, exactly as any other arm would.

  • J-

    Seems needlessly complicated. The nice thing about locked breach guns is that the only “calibration” needed for varying calibers is the weight of the recoil spring.

  • Anonymous

    You say “mundane”, but I kinda like the way it looks. The lines, profile and overall simplicity of the styling makes it look appealing to me. But the weird operation and the country of origin would dissuade me from making a purchase of it was for sale here in the free world.

  • SD3

    “…it exerts tremendous pressure in the direction of the rifling’s rotation,”

    Isn’t the pressure in the direction *opposite* the rifling? I.e. Rifling is clockwise, so perceived torque is counter-clockwise?

    • AlDeLarge

      It’s opposite the direction & rotation of the bullet, but both try to go in the direction of the rifling. The rifling (LHT) goes forward & counter-clockwise, and rearward & clockwise.

  • El Duderino

    Hey stop copying Guest!

  • Its commercial version has been showcased at the NORINCO booth at the 2014 IWA expo in Nuremberg (Germany); it was labeled the “NP-42 Qx4”.

    http://www.all4shooters.com/en/specials/Trade-shows-2014/IWA-2014/pistols/Norinco-Qx4-NP42/

  • Wetcoaster

    I get the impression that they left some bored engineers access to the machine shop. Maybe they should have put them to work improving the ergonomics of the Type-97 instead.

  • patrickiv

    Damn I want one.

  • Timothy G. Yan

    As someone who wrote an article on the Chinese Type 92 pistol family, this is basically a farther development of the CF-07 single stack compact 9mm pistol. I’m not sure if it’s complete retard blow-back, it may has a very quick lock time with the spiral fluts to slow down the slide after firing.

    FYI, the Chinese have been working on spiral fluted retard blow-back action since the 1960s with the start of the Type 64 pistol based on the Walther PPK. The 5.8x21mm version of the Type 92 is the first to uses rotating barrel as the retard mechanism. Breech is not lock during firing on the 5.8x21mm variant. Btw, the 9mm version of the Type 92 has 8 small lock lugs on the barrel in 2 clusters, and it’s proven that it can handle +P+ pressure w/o problem.

    The QX-04 have been around for few years now, and nothing have came out of it besides the prototype. So, the design may not work that great.

  • Chase Buchanan

    Invented in China?

  • Chase Buchanan

    Not quite. The Px4 Storm’s slide and barrel start moving backward right away, and unlock when the barrel rotates as it cams against a lug. This QX-04 pistol’s barrel is (theoretically) prevented from unlocking as long as the spinning bullet PREVENTS the barrel from rotating.

    Both barrels rotate, but for different reasons.

  • strongarm

    Some facts about firearms(Arguable of course);

    – Barrel rotation occurs at opposite direction of rifling,

    – Maximum pressure inside the barrel occurs in some half milisecond of a time and with
    existing pistol slide weights, it causes maximum five milimeters blowback,. Beyond
    that distance, everytime simple blowback counts,

    – In recoil action firearms, backwardly movable barrel retains its foremost position
    through the plugging effect of forwardly moving bullet provided with zero gas leakage.
    This is the basic cause of why slide begins to go backward travel after the bullet goes
    out of the gun,

    – If a freely rotatable barrel stays unrotated through bullet pass, it is because the Blish
    effect since different kind of metals tend to stick each other under high pressure.
    Sticking occurs between case walls to chamber and case back to breechblock head,

    Eventually,

    -This Chinese pistol is an expensive version of Savage 07 or MAB P15 from Western
    standarts, but may be made cheaply through Chinese manufacturing costs,

    – It will not survive long.

  • gunslinger

    got a gif of the firing sequence?

  • noob

    never go full blowback

    (at least unless you have a massive slide)

  • Mystick

    …that’s “RIFLING”, not “RILFLING”…