The FN P90, developed by FN Herstal in Belgium, is a groundbreaking personal defense weapon (PDW) introduced in 1990.

Chambered for the 5.7×28mm cartridge, this compact and powerful firearm was designed to meet NATO’s need for a versatile weapon to replace traditional 9×19mm Parabellum firearms.

With its unique bullpup design, top-mounted magazine, and fully ambidextrous controls, the P90 quickly became a favorite among military, law enforcement, and special operations forces worldwide.

This article investigates the P90’s development, innovative features, and its significant impact on modern warfare and law enforcement.

The Legacy of FN Herstal

When you hear the name Fabrique Nationale d’Herstal (FN Herstal), you’re talking about a company that’s been shaping the battlefield for over a century.

Born in the heart of Belgium in 1889, FN Herstal didn’t just pop up overnight—they’ve been building a legacy, one firearm at a time. From collaborating on the creation of the iconic Browning Hi-Power to the ubiquitous FN FAL, their guns have been the choice of soldiers and law enforcement officers around the globe for decades.

FN’s knack for innovation has set them apart. They craft weapons that are not just tools but extensions of the user’s will in combat. When you pick up an FN firearm, you’re not just holding a gun—you’re holding a piece of history, a testament to years of battle-proven engineering.

Development and Production

The P90’s journey began in 1986 when FN Herstal started developing a weapon that could meet NATO’s requirements.

FN P90 2
A Cypriot National Guard member holds an FN P90 submachine gun. (eLNuko / Wikimedia Commons)

The goal was to create a shoulder-fired personal defense weapon along with a small caliber, high-velocity 5.7×28mm cartridge. By 1990, the P90 was ready for production, and it was known as Project 9.0, which is where the “90” in its name comes from.

Evolution of Ammunition

Initially, the 5.7×28mm cartridge, called the SS90, was produced alongside the P90. This cartridge propelled a 23-grain plastic-core projectile at a high muzzle velocity, about 2,3oo feet per second.

Herstal didn’t stop there. In 1993, they introduced the SS190, a redesigned cartridge with a shorter, heavier projectile featuring an aluminum and steel core. This change allowed for better performance and compatibility with the FN Five-Seven pistol developed as a companion weapon.

FN Five Seven pistol
Double trouble with a pair of FN Five-Seven pistols and Lauren Young. Image Credit: Athlon Outdoors

Design and Features

The P90’s design is unique. It’s a bullpup configuration with an integrated reflex sight and fully ambidextrous controls.

Its compact, futuristic appearance isn’t just for looks—it’s packed with innovations. The top-mounted magazine and FN’s high-velocity 5.7×28mm ammunition are just the start. The weapon also features interchangeable visible or infrared lasers and a tritium light source.

Compact and Ergonomic

The P90 was designed with tight spaces in mind. Its length is no greater than a man’s shoulder width, making it easy to carry and maneuver inside vehicles. It’s also easier to shoot yourself in the lower extremities if you are not careful, so I remind you again to always use extreme caution when handling a firearm and keep your booger picker off the trigger until you are ready to shoot something.

Frogman with FN

The bullpup design places the action and magazine behind the trigger, eliminating wasted space. This unique feeding system, where the magazine sits parallel to the barrel on top of the frame, contributes to the P90’s compact profile. It’s the most compact fixed-stock submachine gun available, measuring just 20 inches long.

Fully Ambidextrous

One of the standout features of the P90 is its fully ambidextrous design. It can be operated by both right and left-handed shooters without any modifications. The charging handle, magazine release, and backup iron sights are symmetrically distributed on both sides. Spent cartridge casings eject downward through a chute behind the grip, keeping them out of the shooter’s line of sight. If you are a shooter with cross-eye dominance, like me, this can be a big plus.

Performance and Maintenance

The P90 is a selective-fire, straight blowback-operated weapon with a cyclic rate of fire between 850 and 1,100 rounds per minute. Weighing just 5.5 pounds empty or 6.6 pounds with a loaded 50-round magazine, it’s lightweight and easy to handle even for the most fatigued operator.

It fires from a closed bolt for maximum accuracy and extensively uses polymers to reduce weight and cost. The weapon is modular, consisting of four main component groups: the barrel and optical sight group, the moving parts group, the frame and trigger group, and the hammer group. The P90’s barrel is cold hammer-forged and chrome-lined, with a service life of 20,000 rounds.

Ammunition: The 5.7×28mm Cartridge

The 5.7×28mm cartridge is a game-changer. Developed in response to NATO’s call for a replacement for the 9×19mm Parabellum cartridge, it’s lightweight and high-velocity. Weighing just 93 grains, roughly half the weight of a typical 9×19mm cartridge.

This means you can carry more rounds for the same weight or the same number of rounds for less weight. The cartridge’s small diameter allows for many rounds in a magazine. It produces less recoil than the 9×19mm cartridge, improving controllability, and has a flat trajectory due to its high velocity.

Penetration and Range

One of the design goals for the SS190 cartridge was the ability to penetrate Kevlar protective vests that stop conventional pistol bullets.

Operator with FN

Fired from the P90, the SS190 has a muzzle velocity of roughly 716 meters per second and can penetrate the NATO CRISAT vest or a Level IIIA Kevlar vest at a range of 200 meters.

FN states an effective range of 200 meters and a maximum range of 1,800 meters for the 5.7×28mm cartridge when fired from the P90. The projectile’s design limits overpenetration and reduces the risk of ricochet, making it safer for use in urban environments.

Real-World Use

Despite being intended as a defensive weapon for non-combat military personnel, most sales of the P90 have been to special forces and counter-terrorist groups for offensive roles.

In 1997, Peruvian special forces used suppressed P90s during Operation Chavín de Huantar to end the Japanese embassy hostage crisis successfully. The operation demonstrated the P90’s effectiveness against body armor-wearing adversaries.

In 2011, Gaddafi’s forces used P90s during the Libyan civil war, and some of these weapons ended up in the hands of Libyan rebels. By 2009, the P90 was widely adopted by military and police forces worldwide.

In the U.S., over 200 law enforcement agencies, including the U.S. Secret Service, use the P90. The civilian version, the PS90, has a longer barrel and is semi-automatic, making it accessible to civilian users.

Ongoing Development

The P90 continues to evolve. In 1999, FN introduced the P90 TR model, which features a Picatinny rail interface for mounting accessories.

Stargate
It can be quite a badass looking firearm in the right hands.

This model is still offered alongside the standard P90. More recently, the P90 has been offered to civilian shooters as the PS90, a semi-automatic carbine intended for personal protection and sporting use. In the video below the shooter will tell you all about his FN PS90.

The Science Behind Plastic-Cored Projectiles

Now, let’s talk about those plastic-cored projectiles that make the FN P90 and FN 90 so special. This isn’t your run-of-the-mill ammo; this is next-level stuff. Imagine a bullet designed to be as light as a feather yet punch through soft body armor like it’s paper. That’s what the 5.7x28mm round brings to the table.

The polymer core inside the jacket isn’t just about shaving off weight—it’s about maximizing velocity and minimizing recoil. This means you can stay on target while your round zips through the air, hitting hard where it counts.

Tritium Sights: Gotta Go With The Glow

There’s nothing quite like tritium sights when the sun dips below the horizon. If you’ve ever been in the dark with your heart pounding in your ears, you know that every second counts.

Tritium sights on the FN 90 aren’t just a nice-to-have but a must-have. Tritium, a radioactive isotope of hydrogen, gives off a steady, faint glow—just enough to keep your sights visible without any external light source.

No batteries, no fuss. It’s the kind of reliability you need when things go sideways in the dead of night. Whether clearing a room or moving through an alley, that glow guarantees your aim is true, even when you can’t see your hand in front of your face. And speaking of hands, another pro tip that should go without saying. Be extra vigilant about keeping your hand clear of the barrel. One mistake in that category could turn them to hamburger in a second.

The 5.7x28mm Round: Small But Mighty

You might be wondering, why did FN choose the 5.7x28mm round over the tried-and-true 5.56 NATO? The answer is all about purpose.

The 5.56 NATO is great for longer-range engagements, but its bulk can be a hassle in confined spaces. Enter the 5.7x28mm — a round that’s light, fast, and just plain nasty when it hits.

Developed to take on soft body armor at up to 200 meters, this round punches well above its weight class. It’s not about size but what you can do with it.

Comparing the FN 90 to the FN P90

You can’t talk about the FN 90 without mentioning its older sibling, the FN P90. Both guns share the same DNA—compact, innovative, and deadly efficient. But where the P90 was designed with a shorter barrel and as a personal defense weapon (PDW) for vehicle crews and special forces, the FN 90 takes things a step further.

The FN 90’s longer barrel means better accuracy at range, making it more versatile in various combat scenarios. It’s like comparing a scalpel to a full-sized sword — both have their place, but one gives you that extra reach when you need it.

The FN 90 doesn’t just match the P90 in performance; it takes the concept and pushes it to the next level, making it a prime choice for anyone needing a firearm that’s both compact and capable of delivering a serious punch at a distance.

Why Bullpup Designs Work for SOF

When asked, SOFREP’s Managing Editor, Guy McCardle,  said the following:

“A bullpup like the FN P90 is ideal for close-quarters work, allowing the operator to maneuver easily and engage multiple targets without frequent reloading. It can help maintain control in dynamic, high-stress environments.”

Special operations forces (SOF) are all about efficiency and effectiveness. They need gear that works as hard as they do, and that’s where bullpup designs come in.

The FN 90’s bullpup configuration is more than just a cool design — it’s a solution to a problem every operator faces: how to keep your weapon short and maneuverable without sacrificing firepower. By placing the action and magazine behind the trigger, bullpups like the FN 90 offer a full-length barrel in a compact package.

This means you get the accuracy and velocity of a standard rifle with the maneuverability of a submachine gun. Whether you’re kicking in doors or moving through tight spaces, the FN 90’s design gives SOF operators the edge they need to complete the mission. And in the world of SOF, that edge is everything.

Some of the notable SOF units that have used or are reported to use the FN P90 include:

  1. Belgium:
    • Special Forces Group (SFG): As a Belgian-designed weapon, the P90 has been used by the Belgian Special Forces Group, taking advantage of its suitability for close-quarters combat and urban operations.
  2. France:
    • GIGN (Groupe d’Intervention de la Gendarmerie Nationale): This elite counter-terrorism and hostage rescue unit of the French Gendarmerie has used the P90 because of its compact design and armor-piercing capabilities, which make it ideal for these operations.
  3. Peru:
    • DINOES (Dirección Nacional de Operaciones Especiales): The Peruvian National Police’s special operations unit, DINOES, has reportedly used the P90, especially in urban and counter-terrorism missions.
  4. Thailand:
    • Royal Thai Army Special Forces: Some Thai special operations units have been reported to use the P90, particularly those requiring high maneuverability and effective close-quarters combat capabilities.
  5. United States:
    • United States Secret Service: While not a military SOF unit, the US Secret Service uses the P90 for its protective details, particularly due to its compact size and the ability to defeat body armor, which is vital in close protection scenarios.
  6. Indonesia:
    • Kopassus (Komando Pasukan Khusus): The Indonesian Army’s special forces are reported to use the P90, likely because of its effectiveness in close quarters and urban environments.

Why Veterans Might Want the FN 90 in Their Collection

For a veteran, the FN 90 isn’t just another gun to add to the collection—it’s a piece of modern military history, a symbol of innovation and practical design. Besides, they’re fun as hell and unique.

The FN 90 is for the vet who values not just what a gun can do but what it represents. Maybe it’s the compact bullpup design that speaks to the need for efficiency or the armor-piercing capabilities that recall tough missions in hostile environments.

Whatever the reason, the FN 90 offers something unique—a blend of cutting-edge technology and battle-proven reliability that any veteran can appreciate. It’s a weapon that tells a story, and for those who have served, it’s a story worth holding onto.

Final Verdict

The FN P90 is a testament to FN Herstal’s innovative approach to firearms design. Its compact size, high-velocity ammunition, and fully ambidextrous controls make it a versatile and powerful weapon for various roles.

Whether in the hands of Special Forces, counter-terrorist units, or law enforcement, the P90 continues to prove its worth on the modern battlefield. The P90 represents a significant advancement in personal defense weaponry for veterans and new users, offering unparalleled performance and reliability.

The P90’s continued use and development are a testament to its effectiveness and the forward-thinking approach of FN Herstal. Whether you’re a seasoned veteran or a new shooter, the P90 is a weapon worth knowing.

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Disclaimer: SOFREP utilizes AI for image generation and article research. Occasionally, it’s like handing a chimpanzee the keys to your liquor cabinet. It’s not always perfect and if a mistake is made, we own up to it full stop. In a world where information comes at us in tidal waves, it is an important tool that helps us sift through the brass for live rounds.