In the mid-80’s NATO had put forth requests for a compact firearm to replace 9mm submachine guns for personnel who couldn’t easily carry or use a full sized rifle. From this request two notable designs for modern Personal Defense Weapons emerged, one being the Heckler & Koch MP7. The other came from Fabrique Nationale out of Belgium from a project first started around 1986. By 1990 it was completed (hence the “90” part of P90) where it sees limited use to this day. Unlike the MP7, the P90 is one of those firearms with a purely unique profile which can be recognized anywhere. Its closest companion is the FN F2000 rifle but even its larger 5.56mm sibling lacks some of the unique twists of the smaller P90.
Just as the F2000 has the civilian FS2000 the P90 has a civilian version known as the PS90. Other than a lack of fire selector and a longer barrel with a built in flash hider required to hit the sixteen inch requirement the two look identical side by side. Coming in at about 6.3 pounds, the PS90 has a whole lot of zaniness going on and is one of the most unique firearms available on today’s market. It’s also seen plenty of screen time in games and media including being the standard issued arm in the Stargate universe.
To dig into the peculiarities it helps to first examine the 5.7x28mm cartridge of FN’s own creation. The 9mm lacked punch against body armor so FN (and HK both) took the 5.56 concept and considerably shrunk it down. Simply put, to defeat armor you need velocity over mass. Firing a tiny projectile very quickly is the way to go. As an added benefit these calibers tend to have lighter recoil which makes for less felt recoil.
To aid in feeding the 5.7×28 is a straight walled cartridge unlike most rifle rounds and even the 9mm which have a slight taper. This allows a greater number of them to be stacked in a line without requiring a curved magazine body. This leads to one of the platform’s coolest features in the industry: A top mounted fifty round magazine which rotates each bullet a quarter turn during cycling. Because the magazine is mounted up top this also allows the firearm to be completely ambidextrous with the spent casings ejecting straight down.
Because of the mild recoil the PS90 can get away with being a simple blowback operation which decreases complexity and increases reliability. Most of the felt recoil comes from the mass of the cycling bolt rather than the bullet.
Additional benefits to this magazine layout are an ultra-compact and well balanced system. The PS90 is the sort of gun you don’t hold so much as wrap yourself around with the integral foregrip keeping both hands close and the swept back angle of both grips allowing for a comfortable hold while wedged against the shoulder. It may look awkward but they are surprisingly ergonomic in a shooting position!
Up front is a non-reciprocating ambidextrous charging handle which is nothing more than a half round nub which you charge by curling an index finger around and pulling straight back. Above this is the sight base which looks like scaffolding over the top front of the magazine. I’m aware of two different receivers with the earlier one having factory optics or Picatinny adapters while an updated one has an integrated Picatinny top with smaller side rails bolted to either side. Because this piece is the serialized component they cannot be freely swapped out.
Directly in back is an ambi magazine catch which I feel is one of the weaker points of the design. Inserting a mag requires dropping the front in and vaguely aligning the back before giving it a firm slap. If you aren’t careful this can become a serious pinch hazard for your hand. To release the mag the catch must be pinched from either side and pushed back while pulling up on the back of the mag. Because of the magazine’s design it sometimes likes to get caught halfway out of the gun and can be a small hassle to fully unlock.
Straight down from this area is the ejection chute which has a hidden surprise buried within the receiver. Not many people realize the PS90 has a dust cover. It’s been out for 31 years and I only now learned of this feature! Just like an AR it pops open automatically whenever the bolt cycles, whether manually or while firing.
Shifting to the lower center we have the trigger and safety selector. The safety’s a curious design just like the FS2000 which is a small ambi drum which is rotated slightly by an index finger. The trigger is smooth, wide, and undeniably polymer, however especially for a bullpup it’s very responsive. It has a tiny bit of take-up but a surprisingly good break. Reset is short with the return spring helping to make it jump to full release which works quite well given the overall short length of travel.
Disassembly of the PS90 begins by removing the magazine then depressing a large button above where the primary grip is. This frees up the entire barrel and receiver assembly much like a Steyr AUG which can then be slid forward of the stock body. Also like an AUG, the bolt body travels on dual guide rods. The trigger pack can be accessed from the back after sliding the thin rubberized recoil pad off of the stock.
Thanks to the balance, mild recoil and good trigger the PS90 is easy to shoot well and is one of the best carbines I’ve ever used for follow-up shots. Getting a tight five round cluster at 25 yards is trivial with a red dot sight. The report isn’t terribly loud either, it’s just fun to shoot! But there is one exception and it’s my next complaint about the design. That cool top-mounted magazine means your cheek weld is going to be on a right angled polymer edge. Even with mild recoil it doesn’t take very long before this edge will become irritating.
My third complaint with the PS90 is not unique to the design. In fact, it seems to be universal among bullpup firearms that the grips have zero texture. They’re just smooth plastic and that’s it, even on the recoil pad. The PS90, the FS2000, the AUG, the Tavor, the X-95, all of these guns have little to no texturing. I don’t understand why the stocks were never updated with something grippier. The AR-15 market has sure stepped up on this front, just put any Magpul grip into your palm and see the difference. The extra texturing would help these slightly heavier bullpups even more.
The last odd detail I’ve found is the barrel has some rotational play in it and I’m not sure why this might be the case. Up front there’s a flat on the barrel which sort of mates up against the lower edge of the receiver but there’s a big enough gap that you can easily twist the barrel back and forth. I don’t know of any other firearm where you can do this.
Despite my small issues with the PS90 none of them are deal-breakers. Unfortunately what makes these firearms not seem like a great option for personal ownership comes down to price and availability. They aren’t cheap, they’re quite rare, and adding to the ouch factor ammo is also pricey and uncommon. Then there’s the really cool magazines which, as you might have guessed by now, are pricey and uncommon. If considering a PS90 for a defensive role then you’re looking at yet another concern in finding good defensive ammo, which is…yep! Pricey and uncommon. The PS90 is definitely one of those pay to play systems.
In a service role the P90 has a fairly unique niche where it does well for itself, though in a civilian market it is regrettably more of a range toy for those who are able to add one to their collection. I do love the P90. It’s a curious and brilliant design which was made to fit very specific criteria and I am always happy to put some rounds through one, but for me it isn’t a must-have for the safe.
