P90: FN’s Bullpup PDW

FN began developing the P90 in the late 1980s, actually preceding the NATO requirement that it would eventually compete for. The idea of the P90 was to develop a weapon for secondary troops to replace 9mm pistols and SMGs. There was an anticipated threat of Russian paratroops wearing armor that could defeat 9mm ball. The P90 was intended to be a light and handy weapon that was easily controllable without a tremendous about of training, and could defeat that sort of body armor.

The result was the 5.7x28mm cartridge, firing a 31 grain armor-piercing bullet at 2350 fps. This was combined with a simple blowback action and a Hall-style 50-round magazine in a fully ambidextrous, bullpup layout. The gun was introduced onto the market in 1990, and has been widely purchased by security and special operations organizations. In its original intended role for support troops, it has only been adopted by Belgium.


  1. Thank you for explaining the reason for the coating, & the reason for the lack of taper. The coating has proved problematic for US reloaders, from what I understand. Loading the magazine was quite confusing when I first went to take my AR-57 Lyndon to the range.

  2. The Five-seveN pistol (yes this is the official company spelling) was not designed from the start beside the P90. It was designed later to compete with the less bulky H&K MP7 that blurred the lines between pistol and SMG sizes.

    As much as the trigger pack looks AUG, it also share the same progressive trigger principle. And when set in full auto, it is quite easy to manage single shots.

    The P90 was also for a time carried by Belgian F16 pilots in their survival kit, nowadays replaced by Five-seveN.

    • Interesting. I recently saw a Russian subtitled show (“Combat Approved”… Excellent show!) where it featured Russian pilots in Syria.

      Apparently they have a Stechkin machine pistol along with 6 magazines IN THEIR FLIGHTSUIT! (Along with a PDW/SMG in their survival pack if I remember correctly.)

      If a Belgian F16 pilot and a Russian SU33 pilot ever manage to shoot each other down, my money is on the Russian surviving the following firefight.

      • It will depend on the range. The Russian will have to get close to score a hit with its spray an pray gun.
        On the other hand, even the Five-seveN pistol will allow for easy hits at long range.
        But don’t forget, these weapons are meant to be defensive…just in case.

  3. Should note in the descriptions that since filming (?), NATO formally standardized the 5.7 cartridge in March 2021.

    Despite the dismissal of the Secret Service’s use, they could very easily be considered to fall within the perimeters the P90 was designed for: Non-combatants who totally need to penetrate armor if they do need to fight. Most agents have duties other than being a kill team (situational awareness, control of non-hostile crowds, inspecting things) and need to minimize the clumsiness of their firearm (esp when many operate indoors) to perform those duties optimally, but need a long gun as a visual deterrent and the odds of them needing to penetrate armor when they do have to fire is actually reasonably high (someone crazy enough to blame the President for their flatulence and willing to charge a protectee could very well bring some armor).

    That aside, the use in SG-1 amuses me because besides being cool looking for TV (and ejecting downward to simplify actor positioning), the Stargate program is actually a legitimate fit for the PDW concept. Outside the dedicated combat teams (who are armed with standard rifles), SG teams aren’t supposed to be combatants most of the time (being primarily diplomats and scientists), but when they do fight they need to penetrate armor. SG-1 fights an awful lot, but that can be blamed on the show only showing their “interesting” missions.

    • I always figured they picked the P90 because someone said: “Find me a supercool and futuristic looking gun!”

      But yeah, you’re right! It’s quite a realistic choice for the job. Why lug around a heavy AK, FAL or M16 when most of the missions are usually fairly peaceful.

      And the P90 with the relatively light recoil from the 5.7 round is a good weapon for scientists and researchers who might have gotten some basic gun training, but don’t have years of experience on a range or in combat.

    • Interestingly also its’ German production become standard, according to http://www.kaliberinfo.hu/hirek/uj-nato-kaliber-57-mm/

      STANAG / AOP 4820 4.6 mm x 30 Ammunition

      STANAG / AOP 4172 5.56 mm x 45 Ammunition and Links

      STANAG / AOP 4509 5.7 mm x 28 Ammunition

      STANAG / AOP 2310 7.62 mm x 51 Ammunition and Links

      STANAG / AOP 4090 9 mm x 19 Ammunition

      STANAG / AOP 4383 12.7 mm x 99 Ammunition and Links

      • Since the reorganization that accompanied the adoption of 4.6 mm and 5.7 mm as NATO cartriges, the STANAGs are relegated to “cover letter” contents. Cartridge description now is in the new AOP documents of the same number (for example 762 NATO in AOP-2310).
        Additional technical information is in the 752 page Multi-Calibre Manual of Proof and Inspection (M_CMOPI), document AEP-97.
        These documents can be downoladed from the STANAG section of the NATO website nato.int
        In a suprising fit of common sense, NATO found it no longer necessary to withhold information about cartridges designed 40 to 120 years ago from the public.

        • From insiders views on the matter, this is actually a political decision. Germany would not accept its pet cartridge being declared as inferior. So it was decided that both cartridges meet the requirements.
          From a technical point, the 4.6 is already at the peak of its possibilities while the 5.7 has still some room for improvement even thought it is already slightly ahead.

          • While I agree with your view of the decision being purely prestige driven, I would like to remind readers that 4.6×30 was developed at Radway Green during the period of UK ownership of Heckler & Koch. See Jane’s Ammunition Handbook, for example.

  4. Very nice to see a piece on the P90.

    I’d looked in the past through the archive of material to find a video, but of course until now, nothing there.

  5. I believe Ian is plain wrong when he writes that only Belgium adopted it.

    It’s a well known fact that the US Air Force adopted it, at least unofficially, for use in black ops. Specifically the so called “Stargate Command”.

    The gun has proven itself an excellent performer. The 50 round magazine lends itself to extensive (and very exciting!) firefights, and the excellent 5.7 round has shown to be very effective against both metal as well as natural armor. (The only exception perhaps when a wraith has just fed.)

  6. This is about 1/3-1/2 the punch of the M1 Carbine, and while that’s been described as an adequate stopper, not overly so. Does this weapon offer a high-speed short burst mode like the G11? That would give you a good chance of putting several bullets on the target, which at least would make more holes.

    • Yeah, but can an M1 Carbine punch through Jaffa or even G’oauld armor? I don’t think so! That’s where that 5.7 round comes in handy!

    • ROF is over 850 rpm and being very controllable, so multiple hits in bursts are possible.
      And the bullet is designed to pierce trought hard material while tumbling trough softer parts of the target. Just like the original 5.56 but adjusted for its velocity.

  7. One option Ian forgot, regarding possible origins.
    FN designed it, lobbied the militaries, demonstrated it, and THEN the militaries realized they had a “need” for the gun.
    Of course, in true US military style, the FN was found to be too expensive and the ammo was an issue for the supply system, and so most NATO nations followed the leader and most NATO uses never came to be.

  8. It might be of interest that Mr. Kalashnikov himself showed up at AUSA held by the end of summer 1998 to see this particular gun. I happened not to be there that day, but fella who spoke with him did not miss to mention that the famous visitor was dressed for the occasion rather “leisurely”. He even made a joke about it I do not prefer to repeat. I regretted missing the opportunity of meeting the man, maybe I could have brushed up my fading Russian. Oh, well.

      • That is well known photo-opp. I wonder in which language they communicated and was their talk about. But still, it might have been a diversion for both.

        Mr. Kalashnikov was asked at least at one occasion if he does “regret” lives of those who were killed by his rifle. He smiled back comfortably saying: “I made it for DEFENCE of my country”. I wonder if Mr. Stoner felt the same about his rifle. 🙂

        • MTK, begins his autobiography with a similar question from a Saudi Muslim

          Under Christianity he would go to hell, under Islam, to heaven.

          He explained his witnessing his fellows getting shot up with a SMG, and his wish to offer them an equivalent.

  9. According to numbers sold and published in Wikipedia, this may not have been called a successful commercial venture. https://en.wikipedia.org/wiki/FN_P90
    But public may not know, what does not belong to it. 🙂

    It was definitely a big addition to FN’s reputation. The F2000 rifle drew on lessons learned from it. The latter was probably lot more a loss than the former.

    • One fact I recall about FNH from past many years is that they dedicated lots of attention to existing and new customers. They had in particular one gentleman who was almost constantly on travel elsewhere in the world. As I recall, he was a man who was on his toes and easy to talk to. I suppose the H&K was doing something of the kind too.

  10. After looking at the ballistics of the 5.7 rd I can’t help but think that an AR SBR would more effective all-round.

    • An AR 5.56 SBR probably give same effective results but with more muzzle blast and noise. Don’t forget an M4 carbine barrel is already on the edge of powder burn efficiency.
      300 BLK is probably better in this scenario if you assume the risks of KB.

    • Sure, but you’re never going to sell any new rifles w/ that kind of thinking. FN is in the gun industry to make a profit – to make a profit, they have to sell guns. They are to be commended for coming up w/ a new & sexy gun to make a profit from, even if it’s not a net benefit for the taxpayer.

      • No offence meant to you
        But a tax funded project ever turning out to be a net benefit to the tax victims who funded it…

        Jack asses and Derby winners spring to mind

        Like I said
        Absolutely not meant to be personal

        • Sure, they serve the “state” represented by government(s) of the time. But, in extension the state is “us”, at least in the theory. So, it’s up to taxpayer/ us to carry the burden. I cannot envision anything else, given the current scheme of things.

        • Oh, I quite agree the P90 isn’t a benefit to taxpayers anywhere, particularly since the AR-15 can be pared down to 3 lbs, light enuf even for typists to carry. But FN is to be applauded simply b/c they’re smarter than the military officers they sold this to, which is their job. The taxpayer should try hiring smarter officers.

          I do have to say, the US’s investments in the 2nd WW & Korea paid off handsomely. The UK’s investment in colonizing the Americas turned up trumps in the long run, as well.

      • I agree, they have to keep going. They are, together with H&K the mainstay of small arms industry. There is a strong sense of purpose of tradition among them – already about 3-4 generations.

    • Hence, the French Armée de Terre’s decision to adopt a slew of HK416 5.56x45mm blasters with 11-in. barrels for their “PDW” while the longer barrel versions go to the bonafide “war fighters” or whatever. At least with the older bullpup FAMAS the weapon was compact but retained a longer barrel for the 5.56mm ballistics?

  11. I still remain dubious of the entire proposition behind this weapon.

    I think it might have a role for gendarmerie-type forces, but any combatant element these days has to be fully prepared to down tools and do infantry-style grunt work. Period.

    If there’s been any lesson to be taken from the last twenty years of conflict, it’s that you have to have the expectation of full-scale combat happening anywhere in the conflict zone; there are no front lines, no rear areas. If you have the mindset that there are “combat troops” and “support troops”, with the former being the only ones you need to train, equip, and prepare for direct combat? You’re delusional.

    Simple fact is, modern combatants are too lethal to engage for most secondary forces like “insurgents”, which is why you see those forces targeting logistics and other elements of the force. It’s deadly to engage combat troops, so you leave them alone. Which leaves us with the spectacle I observed in Iraq, with the logistics folks generating contact after contact, every damn night, while during the days, the combat units would go out on sweeps and find dry hole after dry hole.

    It’s especially important when you consider the fact that if you want to eliminate the insurgent, you first have to find him. Don’t make contact? He’s not going to sit there and let you run him down. The only time he’s going to raise his head is when he’s attacking your logistics and other efforts, so you absolutely must make sure that all of your soldiers engaged in those tasks are capable of combat and willing to engage and at least fix those bastards in place until you can move up more forces to destroy them.

    That’s the only way to win, these days. You cannot have a two-faced force, one that does combat and one that does not. You do that, and you’re guaranteeing that the only people to see combat will be your unprepared logistics types.

    This being the case, you need to bite the bullet and give everyone the same level of combat equipment, small arms, and training. If you can’t, then I’d suggest that the people you’re reducing to second-class combatants may just as well be civilian contractors, for all they’re contributing to the fight.

    As such, I don’t think that PDW weapons like the P90 have a real role, going forward. Outside of some very specialized roles like bodyguard, these things don’t belong in military hands at all. You need to give everyone carbines with optics, and train them to use them proficiently, as well as instilling enough aggressiveness into them that they’ll take the fight to the enemy.

    • The only realistic role for the PDW is as a police or civilian defense weapon.

      When the problem is a drug-fueled mob of would-be utopians with initials (HackBcoughLchokeMahemmm) a handgun or even a police shotgun just isn’t enough.

      Sixteen round of 9mm, six rounds of 12-gauge, or even 30 rounds of 5.56 just mean that the majority of the 100 or so will kill you before you can reload.

      50 rounds of 5.7 x 28 will at least make them reconsider doing anything that would compel you to initiate IA.



      • The problem I have with the P90 and to a lesser degree even the MP7 is that they are just too damn big. They cannot be tucked away in a holster (the P90 certainly can’t, but I know there are holsters for the MP7). That makes them poor replacements for semiauto pistols for soldiers who really can’t carry even carbines, because they simply have no space for one. By that I mean tank crew members and pilots, perhaps some others. Soldiers like artillerymen and logistical crews usually can carry a carbine without too much trouble (even self-propelled artillery guns tend to have more room than tanks), so they shouldn’t be using a PDW in the first place just like you and Kirk wrote.

        So, instead of a fancy high velocity small caliber cartridge, which necessities a long barrel for good effect, I would rather choose 9×19mm (despite the lesser penetration) and end up with something like the Polish PM-84P. Modernized of course like the PM-06 (albeit the PM-06 has an unnecessarily long barrel for a PDW). The dimensions would be more manageable, but the gun would still have an integrated shoulder stock, which is a necessity if the weapon is supposed to be better than a pistol. A separate holster doubling as a shoulder stock like the Stechkin or VP70 is simply too slow to deploy.

        • Carbines are fine until you need both hands for doing your primary duty (e.g. building bridges), then a holstered PDW comes into its own. Holster also means that its is less likely to be left in the truck cab while the driver is unloading cargo (e.g. ammo to AFVs). Even a Sterling SMG is too cumbersome for aircraft mechanics (e.g. me during 1979 to 1987), so SMGs get left on the hangar floor while clambering over expensive CF-18s. No-one wanted to risk puncturing an expensive composite panel with a cumbersome slung SMG.
          As issuing everyone (first and second line) with carbines … yes, it simplifies training and logistics, but M4 carbine is at its limit of development with poor muzzle velocity caused by the too short barrel. Far wiser to use a bullpup that retains an 18 inch barrel to extract the maximum muzzle velocity from a 5.56 mm (or similar intermediate) cartridge.
          Even a P90ish PDW firing 9 X 19 mm pistol ammo has 1.5 times the muzzle velocity and twice the muzzle energy of a short-barreled pistol firing the same ammo. Anything with a shoulder stock is infinitely more accurate than a simple pistol.
          As for sights, modern optics can be bolted onto any firearm with Picatinny Rails. Simple optics should be issued on every weapon larger than a pistol.

    • Kirk,
      I always respect and generally agree with your assessments. I agree that “You cannot have a two-faced force, one that does combat and one that does not,” and I’m not a fan of the P90 (or the MP7) as executed.

      That said, they weren’t developed with a mindset of “front lines” and “rear areas”, but rather the exact opposite. Modern technology requires combat tasks that make it impossible for everyone to carry a “real” carbine, and the usual “solution” (in 1990, and sadly still today) is a 9mm pistol. A specific assumption of the PDW idea was exactly what you wrote: since infiltrators (albeit Spetznaz rather than insurgents) could create “full scale combat anywhere in the conflict zone”, support troops and vehicle crews need something better than an M9 to fight back. While I don’t like cartridges that trade useful terminal effects for soft-armor penetration – a poor choice unless one is facing WWII bomber crews – the fundamental idea (a shoulder-fired weapon less obtrusive than an M1 Carbine or M4) is far preferable to a conventional handgun.

    • When I was on active duty in the Bundeswehr back in the early 2000s, some people were talking up the PDW concept as the MP7 had just been adopted (but was still nowhere to be seen in regular forces, of course).

      In response I used to quip that a) I was glad money was tight so we’d keep our full size rifles for a long time to come and b) “self defence weapon” for engineer troops in the Bundeswehr had meant 20 mm machine cannons during the Cold War…

      Fast forward almost 20 years and the Bundeswehr has replaced the old MP2 (known as the Uzi to the rest of the world) with the MP7 and that is it. So company commanders, motorcycle messengers, tankers and other roles that never had a full size rifle in the first place now have a modern PDW instead of an obsolescent SMG and everyone else still has a G36 (as the small number of “cool” shorter G36K went to the paratroopers and the special operations forces). I’m fine with that.

  12. The cartridge is outright rubbish.
    All and sundry were playing with such cartridges.
    SCAMP turned out to be the most successful, but it also sank into oblivion.
    Weak target action makes the weapon ineffective. And in combination with a big explosion of the muzzle, it is also uncomfortable to use.
    This does not correspond to either the role of the PDW or the police weapon.
    The only adequate use is the prop of pseudo-sci-fi films.

    If the idiots from the FN had enough foresight to use an analogue of the 4,6×30 cartridge, they could get a pretty decent compact machine gun.
    And as it stands, it’s a waste of money for ammunition and licenses.

    • The 5.7 coming out of the P90 has about the ME of commercial 9 x 19mm, i.e. around 350 FPE. Its sole advantage is that it penetrates soft body armor better than 9mm does.

      In the Five-seveN pistol’s shorter barrel, it has about the ME of a .22 WMRF, with greater blast and flash. A .22 WMRF pistol is cheaper, and so is the ammunition.

      Either way, it makes a .22 caliber hole. Period.

      If you want real power from something like this, the bullet needs more velocity. About 1,000 m/sec is the “ground floor” for serious killing power, as “varmint” shooters have known for decades and Eugene Stoner knew when he designed the original AR-15 in 1954-55.

      For a lighter bullet like the 5.7 x 28, at least 1,500 m/s is going to be necessary.

      Physics always wins.



  13. “…About 1,000 m/sec is the “ground floor” for serious killing power…”(C)

    For the “water wave effect” in contact with meat, 730-750 m/s is enough. Provided that the bullet does not collapse into dust.
    In practice, the HK MP7 just steps over the lower threshold.

  14. Just a word in praise of industrial design here, regardless of the weapon’s merits. What a remarkable construction — held together by one large solid sprung button, the buttplate sliding on grooves held positively by the recoil spring guide, and I am particularly wowed by the hexagon-shaped hammer spring loop bearing on the nut-shaped protrusion on the hammer. A lot of original thinking, and just plain thinking, went into this, beyond the ballistics and military purpose.

  15. In the video, Ian states that the extractor is on the top of the bolt and the plunger is on the bottom. I think it is the opposite as it is bottom ejection (should be extractor on bottom, plunger at top).

  16. The idea that 2nd line units will be issued something which is A) new/futuristic and B) small and handy and C) high-firepower while fighting units keep the same old same old is…not realistic with how military units work. No way a truck driver is going to have a P90 while special ops or counter terrorist units has a FAL or ab Uzi.

    • Yes, that is exactly what happened with the PDWs – a lot of special units called dibs on the new hot shit and everyone else only started to get their PDWs when the cool guys had all they wanted (which, thankfully, was not an awful lot in pure numbers).
      Curiously, the German KSK not only grabbed all the early MP7s, they also had a special model made shortly after. ’cause otherwise the MP7 wouldn’t be cool enough any more when the 2nd line guys got it, too 😀

  17. Ian, there are backup iron sights on the P90 in your video. In fact, there are TWO sets of them, to the left and right sides of the prism optic, and just inside the two side [Picatinny] rails — to accommodate sighting with a cheek weld on either the left or right side of the stock.

    The FN prism sight was designed and manufactured by Kingsview Optics. It is a solid glass prism with the reticle etched into the glass. The most current version has an internal illuminator that can be manually switched on / off, and which causes the reticle to emit a green “glow.” The illumination intensity can be adjusted by the user. Unlike “red dot” optics, the reticle on the FN / Kingsview prism sight remains much more sharply defined for users with advanced stigmatism.

    FNH once offered a laser sight option, built into the P90 stock, with an activator button beneath the thumb-hole grip and the laser diode situated in the front face of the stubby “hand stop.”

    One of the fascinating aspects of the P90 action is the looseness of the barrel. If you place your palm on the muzzle of the barrel and push in, it will “give” and slide into the receiver. Also, the barrel rotates from side to side by about 10 degrees each. This looseness is needed to gain reliable chambering and extraction of the cartridges in full auto operation. On the semi-auto only carbines, i.e. P90, FN cinches down on the rear nut that retain the barrels in the receiver to remove the slack.

    Please ensure your carbine is unloaded and with no round in the chamber before you press on or try to manipulate the muzzle with your hands.

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