The Fabrique Nationale FN P90 is a Belgian-originated "Personal Defense Weapon" with qualities akin to both a submachine gun (SMG) and an assault rifle. The gun was originally developed to arm indirect auxiliary combat units such as vehicle crews, messengers and clerk-type elements within the army with a potent, portable man-stopper. As with many other current, and emerging automatic weapons, the P90 is arranged as a "bullpup" assault weapon where the action and magazine feed are concentrated aft of the trigger unit. This allows a full-length barrel to be used with a more compact package. The result of this mating is a fixed, slightly oversized stock with integrated pistol grip and carrying handle. Due to its compact footprint, the P90 is an ideal weapon for second-line forces not requiring the commitment to a full-length assault rifle.
Design is attributed to Stephane Ferrard, begun in 1986, with serial production forthcoming in 1990 through the storied concern of Fabrique Nationale de Herstal of Belgium.
One of the interesting physical qualities of the P90 is its translucent, swiveling 50-round magazine made of polycarbonate. This is mounted over the receiver with the feed positioned over the stock. Individual cartridges are inserted into the magazine in a traditional fashion and automatically rotated to rest at a 90-degree angle to the receiver. Ejection of spent shell casings is through a port at the base of the pistol grip. The charging handle, found along the sides of the receiver ahead of the trigger group, can be managed with either hand due to its ambidextrous design. Safety / firing controls are contained near the base of the grip. The barrel is of forged steel and capped by a flash suppressor. Overall body construction of the P90 remains mostly high-tolerance alloy and polymers. The P90 supports use of a sound suppressor and this can be coupled with subsonic ammunition for reduced-noise operation - a particularly useful feature for clandestine operatives. The weapon also features select-firing through single-shot and full-automatic fire. The including rail system can adapt a variety of optics and aimers as needed.
Unlike other Western-originated submachine guns that center on the ubiquitous German 9mm Parabellum pistol cartridge, the P90 is engineered to fire the specialized, high-velocity 5.7x28mm cartridge (SS190 Ball). These cartridges certainly maintain a unique look when placed alongside 9mm and 5.56mm types.
The pistol grip, optical sight (low light and daylight use, non-magnifying) and trigger guard are all inherent components of the P90's design. Field-stripping breaks the system down into four major components. The oversized stock also aids the shooter with improved stability when firing from the shoulder with a two-hand hold. Recoil is very low, as is muzzle flash, with engagement ranges out to 656 feet.
The P90 has since appeared in various roles - military, security/police, civilian. Two major variants are the P90 Standard and the P90 Tactical. Subvariants, with subtle changes and additions, have also been introduced.