Unique, compact, and “what the heck is that?!” The FN PS90 may be a bit of an ugly duckling, but this curious bullpup rifle is so much more than meets the eye.
The PS90 is the civilian-model little sister of the P90, both manufactured by the Belgian gunmaker Fabrique Nationale de Herstal, commonly referred to as FN. The main difference between the P90 and the PS90 is the action. While the P90 had full auto, select fire capability, the civilian-friendly PS90 is a semi-auto.
Originally developed as a personal protection rifle for military and law enforcement use, the purpose of the P90 was to replace the pistol-caliber carbines commonly in use and offer an option that could deliver a round capable of piercing the lightweight body armor that was becoming popular.
Curiously enough, FN chose a rather unconventional round for the P90—the 5.7x28mm cartridge. Essentially, this round is approximately half of a 5.56×45 (.223 Remington) cartridge, which was NATO’s go-to cartridge and the choice of small and medium-sized varmint hunters. There’s a reason for this smaller ammo size, though. The 5.7x28mm’s reduced size and taper allowed FN to use smaller stick magazines, that still had a 50-round capacity.
The PS90 looks a lot like its older sister—and can even use the 50-round mags the P90 uses—but its semi-auto status and slightly longer barrel puts it safely into the civilian-use category.
So, what did we think of the PS90?
Let’s talk about that and take a closer look at the PS90’s fit and finish, trigger, reliability, maintenance, and more!
Fit and Finish
When the P90 first was introduced, the revolutionary design and polymer construction was pretty modern. The polymer body of the rifle is a now-iconic design that’s inspired its use in a number of film, television, and videogame appearances—including many episodes of the Stargate franchise and various Call of Duty games.
The PS90 does have a slightly longer barrel than the original P90 so that it meets the minimum required length to avoid being labeled a short barrel rifle (SBR). The 16.04” barrel is cold hammer-forged and chrome lined. It also is equipped with a ported muzzle brake, which increases the length of the rifle by a little bit.
Despite its larger stature than the P90, the PS90 still is plenty compact and will work well for personal defense situations in tight quarters.
The stock design makes the PS90 not only unique looking, but pretty ergonomic to boot! The thumbhole design and minimalist design of the stock make for a comfortable rifle, whether shooting at the range for an afternoon or carrying the PS90 all day.
We also love that the PS90 is fully ambidextrous, with dual magazine releases, charging handles, and a molded sling attachment point. The manual safety can be operated from either side of the rifle, as well. The ejection port is located on the bottom of the rifle, just forward of the buttstock—a bonus for lefties and courteous shooter-to-the-rights. The PS90 can be equipped with a shell catcher bag, which is perfect for reloaders.
Originally, PS90s came with a permanently mounted FN Black Reticle sight, but they’ve since moved towards a MIL-STD 1913 accessory rail with back up iron sights. The original FN reticle sight is just one of the many optics options you can select for your PS90.
Interestingly, the 5.7x28mm ammo doesn’t provide enough pressure to require a locked breech action. Instead, the PS90 has a blowback action. Because of this, the PS90 enjoys considerable reliability.
Trigger
Like other bullpup rifles, the trigger on the PS90 sits far forward of the action, so it uses a sliding trigger. The trigger on the PS90 has a smooth pull and a crisp release. The PS90’s stock plastic trigger has a 6 lbs., 13 oz. pull weight.
Your safety switch is located at the bottom of the trigger in the trigger guard. This means it’s easy to manipulate the safety with your trigger finger, regardless of which hand is your dominant hand. However, its close proximity to the trigger may be tricky to learn at first without firing the gun.
Accuracy and Recoil
Reviewers reported great accuracy results, especially at close-quarters ranges. Since the PS90 is a personal defense weapon, it’s great to see that it performs well at ranges up to 50 yards. Once sights were dialed in, the PS90 had no problem hitting the target.
Achieving a solid cheek weld isn’t hard, thanks to the unique design and light weight of the PS90. For defensive uses, you’ll find that the PS90 has decent enough accuracy out to 100 yards—though you might not be winning any sharpshooting competitions with it, unless you’re Major Carter.
The PS90 has very low recoil, making it a great choice for shooters looking for less kick and better rapid-fire accuracy. Even though the PS90 weighs so little, the slightly underpowered ammo it uses means that you can keep shooting without struggling to remain on target.
Reliability
The complicated-looking magazine feed system may seem a likely culprit for poor reliability, but it couldn’t be further from the truth. In fact, many reviewers were surprised to discover that the PS90’s reliability was stellar—many experienced no failures, even with several thousand rounds tested.
Magazines and Mag Release
If the rest of the PS90 is considered unique, the magazines this rifle uses are truly unlike anything else. The original P90 used an incredibly compact 50-round magazine, though FN downsized the capacity for the PS-90 to either 30 rounds or 10 rounds. No worries, though—the PS90 will accept the 50-round mags, too!
The magazines are made of translucent, smoke-colored plastic and numbered, so it’s easy to tell how many rounds you have left. These mags load similarly to a traditional box magazine, but this is where the innovative design of the PS90 really shines. As you load the rounds into the magazine, a helical ramp twists the round 90 degrees and aligns them sideways in the magazine. As you fire, the rounds twist back up the ramp and align with the action.
This incredibly simple design means that you get fantastic reliability, even when rapid-firing.
To load the magazine, all you need to do is slide the bottom end of the magazine underneath the sights and drop the open end into the top of the rifle. While a few videos out there feature shooters smacking the mags into place, it really isn’t necessary—the PS90 is incredibly easy to load.
Maintenance & Disassembly
Looking at the PS90’s build, easy disassembly may not be the first thing that crosses your mind. We were pleasantly surprised to learn just how easy it is to field strip the PS90 into its four major component groups.
Simply press the barrel release button to remove the barrel. Once that’s been removed, you can slip the moving parts group off of the gun, which contains the bolt and recoil assembly. The removal of the moving parts group opens up the butt plate, which slides up to reveal the hammer group hidden inside the stock.
Stripping this rifle down could hardly be easier.
Specs at a Glance:
- Type: Semi-automatic only. Blowback operated. Closed bolt system.
- Caliber: 5.7x28mm
- Capacity: 10 or 30 rounds, 50 rounds for P90 mags
- Weight: 6.28 lbs.
- Barrel: 16.04”
- Overall Length: 26.23”
- Construction: Molded polymer stock. Black oxide coated alloy steel upper receiver.
- Trigger: Sliding trigger
- Safeties: Ambidextrous safety switch inside the trigger guard
Bang for Your Buck
There’s one downside to the PS90—it’ll definitely put the hurt on your wallet. The MSRP puts this rifle at around $1,500 for the Standard model. Upgrading your optics and rail will only make that cost worse.
For a rifle that uses an unusual ammo type and has limited options to modify or upgrade, it can be a little hard to justify the price for a semi-auto rifle that really only shines as a self-defense weapon.
Upgrades
Unfortunately, there just aren’t too many options to upgrade your PS90. For those who are interested, though, here are a few ways you can make your PS90 your own.
SBR
The P90 comes with a 10.39” barrel, though FN opted to give the PS90 a barrel that was just barely over the minimum length to avoid being considered a short barrel rifle (SBR). If you’re willing to go to the work of getting approval from the ATF, you can “manufacture” your own SBR version of the PS90.
You’ve got a few options to shorten your barrel. You can DIY it, which involves removing the entire barrel unit, removing the barrel shroud from the barrel, cutting down the barrel, re-crowning, and rethreading it. You can send it to a licensed Title II manufacturer to handle the SBR process. This route does have its advantages, including that you won’t need to handle the actual work or engrave your name on the gun as the manufacturer.
The third option is to file all the proper paperwork and pick up a kit, like the CMMG PS90 10.4” Short Barrel Rifle Kit with P90 Style Compensator. This isn’t the least expensive option, but if you don’t want to get into some serious gunsmithing, a conversion kit can be a way to still manufacture an SBR out of your stock PS90.
CMMG PS90 10.4” Short Barrel Rifle Kit with P90 Style Compensator
Pros
- Easily change your PS90 to an SBR without cutting down the barrel
- Comes with a P90-style flash hider
Cons
- Expensive
Triggers
The trigger on the PS90 is pretty popular, but if you’re looking for a better option, there’s a handful of upgrades out there. Here are a few we’ve found for you.
K&M Aerospace Lightning Improved Trigger Spring
Want to lighten up the trigger in your PS90? The K&M Aerospace Lightning trigger spring is just the thing!
K&M Aerospace Lightning Improved Trigger Spring
Pros
- Reduces trigger weight to about 4lbs
- Proprietary design
Cons
- Requires hands-on installation or sending your trigger pack in for installation
This improved trigger spring brings the trigger pull weight down to about 4 lbs, instead of the 6 lbs., 13 oz. pull weight of the stock trigger.
Best of all?
You have the option to send K&M your trigger pack so they can install the spring for you. They also make it easy to do it yourself with an easy-to-follow instructional video.
Man Kave PS90 Trigger Pack Upgrade Kit
For an all-around improvement of your PS90 trigger, we recommend the Man Kave PS90 Trigger Pack Upgrade Kit. This kit includes an aluminum hammer and sear machined from solid billet 7075-T6 aluminum.
Man Kave PS90 Trigger Pack Upgrade Kit
Pros
- 7075-T6 aluminum construction
- Reduces felt trigger weight and pull length
Cons
- Increases the weight of your already lightweight trigger pack
This kit is designed to reduce your trigger pull length and felt weight for an even smoother shooting experience. This kit does increase the weight of your trigger pack by a little bit, but the heavier hammer impacts the firing pin harder for better primer strikes.
Optics
The PS90 is friendly with about any Picatinny mounted sight or optic you could want, so there are quite a few options available. Some shooters prefer to replace the Picatinny rail with another type of mount, especially since a rail-mounted optic can get a little bulky on the small profile of the PS90.
If you’re looking to throw a good optic on your PS90, we’ve got some suggestions.
Holosun HS403
We’re big fans of the Holosun HS403, since we’ve found it to be a fantastic value for what you spend on it. This red dot sight is pretty popular with the AR-15 crowd, but that doesn’t mean it doesn’t have a place on your PS90.
Holosun HS403
Pros
- Waterproof
- 8-hour auto shutoff feature
- 50,000 hour runtime
Cons
- Optic needs to be removed to change the battery
It’s got a battery life of 50,000 hours with an 8-hour auto shutoff feature. It’s also waterproof, so it can stand up to the weather just fine.
We particularly like the crisp red dot produced, the wide field of view, and the crystal-clear glass this optic uses—not to mention the budget-friendly price.
Burris Fastfire III Red Dot
Another popular option around here is the Burris Fastfire III. This extraordinarily lightweight, low-profile red dot is a perfect compliment to the small frame of the PS90. If you’re looking to cut down on the size of your PS90, the Fastfire III is a great option.
Burris Fastfire III Red Dot Sight
Pros
- Nine-hour auto shutoff
- Weighs less than 1 ounce
- Budget-friendly
Cons
- Not as durable as more expensive red dots
- Less brightness settings available
This red dot comes in 3 MOA dot and 8 MOA dot models, so you can choose if you’re looking for better accuracy at a distance, or if you want your PS90 to be ready to rumble in short-range, fast target acquisition situations.
The Burris Fastfire III can be mounted on the factory Picatinny rail, but it also can be mounted to a low-profile red dot mount, which we’ll talk about below.
Trijicon RMR LED Red Dot
Our last pick for this list is the Trijicon RMR LED red dot. This optic is a fan-favorite, and for a good reason—it’s incredibly durable, easy to adjust, and is perfect for both pistols and rifles.
Trijicon RMR Type 2 Red Dot Sight
Pros
- Compatible with most popular pistols
- Incredibly rugged
- Low forward glare
Cons
- Expensive
- Battery door is on the bottom of the sight
You’ve got flexible mounting options, including the stock Picatinny rail on your PS90 or a low-profile mount for a more compact build.
The Trijicon RMR red dot boasts a number of awesome features, including adjustable brightness, adjustable windage/elevation controls, and LED illumination that won’t fade over time the way tritium will.
PS90 Low Profile Red Dot Mount
The stock Picatinny rail lets you enjoy considerable flexibility, but it does elevate your optics a considerable amount, which can be a big deal when you’re looking to trim inches on the already ultra-compact PS90. That’s why we like the PS90 Low Profile Red Dot Mount from FN Specialties.
PS90 Low Profile Red Dot Mount
Pros
- Low-profile design puts your optic close to the axis of the rifle
- 6061-T6 aluminum construction
Cons
- Required removal of the stock accessory rail
This optics mount is designed especially for the PS90 and lowers your optics closer to the axis of the rifle. The mount is machined from 6061-T6 aluminum for durability.
It’s removable, and FN Specialties brags that this mount is so well fitted, it can be removed and reinstalled without losing zero.
For those of you wanting to keep your PS90 trim and ready for action, you should definitely invest in a PS90 Low Profile Red Dot Mount.
Conclusion
All in all, we like the PS90, but we don’t feel like it’s the most useful option out there. We appreciate that its light weight and completely ambidextrous build makes it accessible to a wide range of shooters, but it’s hard to justify the price.
The P90—and PS90, by extension—were designed for a very select use, and it just isn’t something most civilians will run up against. The PS90 offers great maneuverability in close quarters, but unless you’re willing to go through the hassle of turning into an SBR, you’re still not using it to its full potential.
Additionally, with its unique ammo size, the PS90 doesn’t have the stopping power of an actual service rifle. It more closely resembles a pistol caliber carbine, albeit a little bit shorter.
We do have to give FN props for completely redesigning the rifle and creating an interesting, surprisingly ergonomic rifle. The PS90 is also a fun option for new shooters, since its low recoil and ergonomics make it a blast to shoot, even if the accuracy isn’t much above average.
Overall rating: 5/10 stars
Do you own a PS90? If so, what do you think about it? Thinking about getting one? Let us know in the comments! For something a little more practical, why not check out our review on the best AR-10 builds we’ve found?
