On The Edge

With the New FN P90 5.7x28mm
by Al Paulson

Military organizations have struggled for generations with two frequently overlapping problems: (1) how to arm troops whose primary mission is something other than the use of small arms; and (2) how to arm troops who need compact firepower for conducting special operations. A remarkable array of pistols, submachind guns and carbines have been fielded over the years in an, attempt to give people such as vehicle drivers, operators of crew-served weapons, support personnel and special operators a weapon with the optimum mix of compact size, hit probability, sustained firepower and terminal ballistics. Recent decades have also seen a similar quest in law enforcement to provide superior sidearms and auxiliary weapons for officers facing a changing tactical environment. The result is that sidearms, submachine guns and carbines developed for the aforementioned special military needs have become widely used tools within law enforcement. One of the most provocative attempts to solve the common requirements of both the military and law enforcement is the select-fire P90 Personal Defense Weapon designed and manufactured by Fabrique National Herstal SA of Belgium.

Russian PSM

It's interesting that one aspect of the changing tactical environment faced by both the military and law enforcement is that an armed opponent may be wearing body armor. In the late 1970s, the former Soviet Union was the first major power to develop a new class of pistol cartridge, the 5.45x18mm PMT, which was designed to penetrate standard body armor with ease, with the ancillary benefits of improving hit probability and minimizing recoil. Developed by Aleksandr Bochkin in 1979, the bottle-necked cartridge appears to be a scaled-down version of the 5.45x39mm rifle round adopted by the Soviets in 1974 for the AK-74 assault rifle. The Soviets developed a new pistol for the new 5.45x18mm round called the Pistolet Samozaryadniy Malogabaritniy, the "Miniature Semiautomatic Pistol" or PSM for short. Designed by Tikkon Lashnev, Anatoliy Simarin and Lev Kulikov, the PSM superficially resembles a Walther PP pistol and will penetrate up to 55 layers of kevlar at realistic engagement distances. With a steel core projectile weighing 2.4-2.6 grams (37-41 grains, which is less than half the weight of the 9x18mm Makarov round it replaced), a muzzle velocity of 315 mps (1,033 fps) and a powder charge of 0.15 gram (2.3 grains), the 5.45x18mm PMT cartridge also provides a relatively flat trajectory and modest recoil. These qualities improve hit probability when troops of average skill use the PSM as a defensive weapon.

NATO Request

Some NATO planners subsequently became concerned about the issue of body armor on the battlefield and decided that the 9x19mm cartridge was now obsolete, since it wouldn't penetrate the body armor they imagined would become standard equipment for infantry troops. These NATO planners informally approached the small-arms industry about the possibility of developing a new class of cartridge to replace the 9x19mm NATO round for personal defense. Only two companies were willing to invest the substantial R&D funds on such a speculative venture; Fabrique Nationale of Belgium and Giat of France began the development of new bottle-neck cartridges in the mid-1980s.

Gun/Cartridge Details

The two companies took somewhat different approaches. Giat concentrated on developing a new cartridge resembling a .30 Luger round necked down to .22 caliber, which they called the 5.7x22mm. Fabrique Nationale not only developed a larger round, the 5.7x28mm, but FN also developed a series of innovative weapons around the new cartridge: a select-fire bullpup weapon with a 50-round horizontal magazine on top of the receiver and an extremely accurate, lightweight (19 ounce), high capacity (20 round) pistol called the Five-Seven. FN publicly announced they were developing a personal defense weapon in 1989 which was scheduled for production 1990. Ironically, however, the P90 was not named for the year of its initial production, but rather for FN's "Project 9.0" which spawned it.

When Giat became the parent company of Fabrique Nationale, Giat abandoned the 5.7x22mm project in favor of FN's more advanced project for several reasons. (1) FN's 5.7x28mm cartridge met all of the NATO requirements. And (2) Giat didn't have a weapon designed for its cartridge, but FN had already developed the P90 for its new cartridge. The first public demonstration of the Five-seveN pistol subsequently took place in 1995, and an improved variant went into production in May 1998. The external ballistics provided by FN's 5.7x28mm cartridge are vastly superior to the performance provided by the Russian 5.45x18mm PMT cartridge. As of this writing, the P90 has been adopted by more than a dozen countries in limited numbers.

With an overall length of just 19.7 inches (.50.0 cm), the P90 is considerably shorter than the 9x19mm H&K MP5 submachine gun or the 5.56x45mm Colt M4 carbine. The P90 weighs 5.9 pounds (2.5 kg) with an empty magazine and 6.6 pounds (3.0 kg) with a fully loaded 50-round magazine, which is similar to the weight of an MP5 with a 30-round magazine. The P90 is just 8.25 inches (21.0 cm) high with a magazine fitted to the weapon.

The P90 features an optical reflex sight (with no magnification), and a three-position rotary selector beneath the trigger with positions marked "S" for Safe, "1" for semiautomatic and "A" for Automatic. When set on A, the selector provides a two-stage trigger similar to the Steyr AUG. Pull the trigger back a little for semiautomatic fire and pull the trigger fully to the rear for full-auto fire. A cyclic rate of 900 rpm enables the operator to obtain two- or three-shot bursts. Shot dispersion remains remarkably tight, thanks in part to the fact that the 5.7x28mm cartridge has about one-third of the recoil impulse produced by the 5.56x45mm round used in the M16 family of weapons. Apparent recoil and shot dispersion are also mitigated by twin operating (recoil) springs and guide rods which, like the trigger, are reminiscent of the Steyr AUG. Sal Fanelli of FN Manufacturing Inc. puts on a particularly impressive demonstration, where he shoots a 50-round burst of tracers into the center of mass in a Milpark target at 50 meters (55 yards). His tightest 50-round burst to date measured 9.5 inches (24 cm).

Three rounds are available for the P90 at this time. The standard ball round, called the SS190, features an overall length of 1.6 inches (40.5 mm), a projectile weight of 31.0 grains (2.02 grams) and a muzzle velocity of 2,345 fps (715 mps). The SS190 projectile features steel core in front of an aluminum core toward the base. The bullet penetrates about 10 inches (26 cm) of 10 percent ballistic gelatin, according to testing conducted at the Royal Canadian Mounted Police Academy in September 1997. The SS190 round will also penetrate 48 layers of Kevlar, the typical "Flak jacket" (including CRISAT protection, which is a combination of titanium and Kevlar) worn by infantry to protect them from shrapnel produced by exploding devices, or a standard PASGT (U.S. Kevlar) helmet at 150 meters (164 yards), which is the effective range of the P90 Personal Defense Weapon. The weapon will still defeat Level 3 body armor at 200 meters (219 yards). The "maximum effective range" using the NATO definition (the maximum range where a weapon's projectile will still deliver 85 joules on target) is 400 meters (437 yards). Thus, according to NATO standards, the P90 is theoretically able to deliver a lethal wound on a protected target at 200m and an unprotected target at 400m if the round hits a vital area. Personally, I would not be enthusiastic about engaging targets beyond 150m with the standard SS190 round.

The subsonic SB193 round used for this testing features a lead core boattail bullet with a projectile weight of 55.0 grains (3.58 grams) and a muzzle velocity of 998 fps (304 mps) as measured by a P.A.C.T MKIV timer/chronograph with MKV skyscreens set 24.0 inches apart and the start screen 8.0 feet from the muzzle (P.A.C.T, Dept. GW/LE, P.O. Box 531525, Grand Prairie, TX 75053; 214-641-0049). A new subsonic round featuring a 77-grain (5.0 gram) projectile moving at the same velocity as the older subsonic round is about to go into production, but no further details were available at press time. A tracer round designated the L191 is also available. The SS190 round weighs about half as much as a 9x19mm or 5.56x45mm round, so carrying a given amount of extra ammunition would be less burdensome for personnel already concerned with impedimenta. Conversely, special operators could carry twice as much ammunition for the same weight.

P90 Operation

Despite the fact that the P90 Personal Defense Weapon fires a bottle-necked cartridge, which looks something like a downsized .22 Hornet, the weapon fires using an unusual method of operation that might be described as a cross between the short recoil and simple Bergmann-Bayard straight blowback principles. Upon firing, the 10.35-inch (26.3 cm) barrel and bolt recoil rearward for about 0.030 of an inch (0.76 mm), enabling the pressure in the barrel to drop to a safe level. When the barrel (which features a 1 in 9 inch rate of twist) stops its rearward travel, the bolt continues rearward in straight blowback fashion. FN Herstal SA seems to have developed a unique flavor of delayed blowback operation. Unlike the typical submachine gun, however, the P90 fires from the closed bolt to maximize semiautomatic accuracy. Recoil is brisk but very smooth, and cycling is reliable thanks in part to an anti-bounce weight in the bolt, which is operated by one of the main operating (recoil) springs. Polymers are extensively used throughout the P90 to reduce both the weight and the cost of the weapon. The human engineering of the weapon is outstanding and ambidextrous.

A variety of features enhance the ambidextrous qualities of the P90. Both sides of the weapon feature a charging handle, auxiliary fixed sights and a magazine release. The manual selector below the trigger can be operated from either side of the trigger. The stock and grips are symmetrical. And the weapon ejects downward, so lefties don't need to worry about hot brass in the face.

One of the most interesting features of the P90, which helps make the weapon so compact, is the polycarbonate 50-round magazine that locks in place between the charging handles and the optical sight. The magazine features a follower with rollers and a constant-force spring that make loading a 50-round magazine easy instead of the usual thumb-busting exercise in frustration. But the most noteworthy aspect of the magazine design is that loading one cartridge forces the rounds under it to eventually rotate 90 degrees to the right so they can slide into a double stack of cartridges in the magazine body.

This rotation occurs in stepwise fashion. The first round in the magazine sits in the magazine's feed lips at the 0 degree position (where it will be aligned with the chamber when the magazine is fitted to the weapon). Inserting a second cartridge forces the cartridge under it to rotate to 82 or 83 degrees from the bore angle. Adding another cartridge to the magazine pushes the original round to the 87 degree position. Adding a fourth cartridge forces the original Cartridge to the 90 degree position in the main body of the magazine. Thus, the cartridges go through a four-step process to become fully aligned in a double stack within the magazine.

Versatile Optics

The optical sight is made from a solid piece of glass so there's no risk of nitrogen leaking and subsequent fogging in the field. It has two complementary reticle patterns for differing lighting conditions.

A day reticle, which is projected into the sight from the front, features a circular reticle which I particularly like since it provides very rapid target acquisition throughout the effective range of the weapon. The reticle has several markings which complement each other. A very large circular reticle provides fast target acquisition at panic-close range, while a much smaller circle is optimized for target acquisition at 100 meters but works very well at closer ranges. A tiny dot inside the smallest circle can be used for maximum finesse; this dot lies 3.7 inches (94 mm) above the center of the bore.

A low-light reticle, which is illuminated by a replaceable tritium cell, is projected into the optical sight from the rear. It is normally invisible in bright daylight conditions unless the sight is shaded by the brim of a large hat. A horizontal reticle runs across the center of the field from one side to the other, and a vertical reticle runs from the bottom of the field to the small circle. These lines form three legs of a traditional crosshair reticle, which can be quite useful inside dark buildings or during low-light operations outside. In those relatively rare lighting conditions where both the day and night reticles are visible, the sight picture is still uncluttered enough to provide rapid target acquisition. This is a very well-engineered optical sight. I wish it were available for the 5.56x45mm M4A1 carbine as well.


The manual selector is positive and quiet, but not as instinctive or fast as the selector on an MP5 submachine gun or M16-type weapon. Other safety features include a safety sear that holds the hammer until the bolt (which FN calls the breech block assembly) has fully closed behind the chamber, and an inertial safety that locks the sear if the weapon is dropped (solving a problem that caused substantial casualties during World War II). Unlike most submachine guns, the P90 is a very safe weapon to handle in the rough and tumble real world. The P90 also has a very high resistance to cook-offs following prolonged full-auto fire. Most end-users fielding this weapon carry a maximum ammunition load of 400 rounds, and the P90 demonstrated no cook-off problems when 400 rounds were dumped as rapidly as possible downrange.

A final curiosity is that the design and materials of the P90 also make the weapon very easy to clean, a process that only takes about four minutes. This appeals to military SpecOps personnel, who tend to have a special affection for weapons that require a minimum of maintenance and, therefore, don't cut into their "Miller Time."

In the next issue we'll conduct a detailed test and evaluation of the P90's performance. We'll also discuss the dramatic operational (i.e., combat) debut of the P90 and implications of that experience for the law-enforcement community. FN will be marketing the P90 and silencer to both military and law enforcement through their subsidiary FN Manufacturing, Inc. located in Columbia, SC. Products are expected to be available in quantity in late 1998 or early 1999...

first published in the November 1998 edition of Guns and Weapons for Law Enforcement