The P90 was developed between 1986 to 1990 by Belgian company FN Herstal and first saw use in the Gulf War by the Belgian Special Forces Group.
Further development has led to the creation of the P90 TR variant, which was introduced in 1999 and continues to be offered alongside the standard P90.
The P90 is a short, compact, lightweight bullpup weapon, chambered in 5.7×28mm. It takes a 50-round magazine; the magazine feeds from the top, and the weapon fires from a closed bolt. The P90 has a 10.5-inch barrel, with a flash hider mounted on it. It uses the straight blowback mode of operation, and the weapon cycles at a rate of 900 rounds per minute. All models of the P90 can take suppressors. Spent casings eject from a port on the bottom of the weapon, eliminating ejection problems with left- and right-handed shooters.
The P90's receiver is polymer, and can come in a few different colors - olive drab and black being the most prevalent.
The P90 has a few variants.
This civilian variant is basically the same as the P90; however, it has a 16-inch barrel, and the option of automatic fire is removed.
The early generation PS90 SMGs have a trigger group with the auto sear included. These trigger groups will have a front sear and a rear sear. To make the gun fire fully automatic, you simply remove the rear sear spring shaft from the detent and lay the shaft on the cam beside the detent. This removes pressure on the rear sear and will result in the PS90 firing fully automatic. In the USA, if you remove the spring shaft from the detent and insert the trigger pack into a PS90, you will have made a machinegun according to U.S. federal law, and if caught, you will be prosecuted by either state or federal authorities.
FN P90 LVEdit
A P90 with an integral laser mounted in front of the trigger guard, just below the barrel. This laser can either be visible or infrared; infrared lasers are for use at night, in conjunction with night vision equipment (as that is the only way the light can be seen).
The standard visible laser has three settings; off, low power, and full power.
FN P90 TREdit
This P90 features a tactical rail on top of the receiver, and two rail sections on the sides of the receiver. The top rail is integral.