This weapon system, comprising the FN P90® sub-machine gun and the 5.7 × 28 mm SS190 cartridge, was developed by FN HERSTAL to equip military personnel whose prime activity is not that of operating small arms – artillery, signals, transport and similar troops whose duties require that they should be effectively armed for self-protection but who do not wish to be burdened by a heavy weapon while performing their normal tasks. It is also a suitable weapon for special forces who require very compact firepower and has police and paramilitary applications.
The 5.7 × 28 mm SS190 was developed as the optimum cartridge for the P90® and is capable of imparting 90 per cent of its kinetic energy upon impacting with a target, a wounding capability enhanced by a distinct propensity to tumble inside the target. It is understood that the bulk of the filling for the lead-free ball projectile is an aluminium alloy material. The ball projectile can penetrate more than 48 layers of Kevlar body armour at 200 m. Recoil forces are stated to be one-third of those produced by a 5.56 mm cartridge (recoil impulse of the SS190 is 1.95 kg m/s).
In May 2000 it was announced that the CyprusNational Guard had ordered 350 P90s for use by their Special Forces. The order included suppressors, laser target designators and tactical flashlights. Apart from the SS190 ball round, tracer, subsonic and blank rounds are available. 5.7 × 28 mm ammunition is also licence-produced in the USA by Winchester-Olin. A pistol firing the 5.7 × 28 mm cartridge is known as the Five-seveN® (qv). In late 1999 the P90®TR (Triple Rail) was introduced. For details see under Variants.
Description of P90
The P90® is a blowback weapon firing from a closed bolt. The overall design places great reliance on ergonomics to the extent that the pistol grip, with a thumb-hole stock, is well forward on the receiver so that, when gripped, the bulk of the receiver lies along the firer’s forearm. The controls are fully ambidextrous; a cocking handle is provided on each side and the selector/safety switch is a rotary component located under the trigger. Even the forward sling swivel can be located on either side of the weapon as required. The magazine lies along the top of the receiver, above the barrel, and the cartridges are aligned at 90º to the weapon axis. The 50 rounds lie in double-row configuration and, as they reach the mouth of the magazine, they are ordered into a single row by a fixed ramp. A spiral ramp then turns the round through 90º as it is being guided down into the feedway so that it arrives in front of the bolt correctly oriented for chambering.
The magazine is a smoked translucent plastic so its contents can be visually checked at any time. The integral sight unit is an HC-14-62 reflex collimating sight produced by Ring Sights, the graticule being a circle and dot; in low light a tritium-illuminated cross-hair appears. It can be used with both eyes open and allows very rapid acquisition of the target and accurate aiming. Should the sight be damaged, two sets of iron sights are machined into the sight base, one on each side; this duplication is another aspect of the ambidextrous design.
Detail design relating to ergonomics is such that the P90® can be carried about the user’s body in such a manner that the smooth outlines impose a minimum of hinderance to movement and user comfort, no matter how it is slung. The weapon strips easily into three basic groups for field maintenance. Much of the body and internal mechanism is of high-impact plastic material, only the bolt and barrel being of steel. Moving parts require little or no lubrication. Empty cartridge cases are ejected downwards through the pistol grip, which is shaped to offer a grip for the disengaged hand when firing from the shoulder.
Externally mounted tactical lights and laser aiming devices can be located either side of the sight assembly on an accessory rail. Also available is a combat sling, a blank firing attachment, a cleaning kit and a magazine pouch and filler. A special-to-type sound suppressor that screw-clamps over the muzzle attachment is available.
Variants of P90 submachine gun
The P90®TR (Triple Rail) has been dubbed the ‘Flat Top’ as the usual Ring Sight sight unit is replaced by a section of MIL-STD-1913 rail, together with two shorter lengths of rail each side. This arrangement allows the user to select an optical or other sighting system suitable for their specific requirements. The side rails can be used to attach combat accessories such as a tactical light or laser aiming device. All other aspects of the basic P90® remain as before, although the loaded weight becomes 2.58 kg.
Special forces variants
Two special forces variants of the P90® are available, each with a laser target designator. The P90® LV uses an 8 mW visible laser for use in low-light conditions and indoor situations. The P90® LIR has a 4.5 mW infra-red laser which can be detected with night-vision devices at night. It is also possible to mount various forms of night sight.
Specifications of P90 submachine gun
Cartridge: 5.7 × 28 mm
Operation: blowback, selective fire, closed bolt firing
Feed: 50-round magazine located horizontally above barrel
Weight: empty, 2.54 kg; with empty magazine, 2.68 kg; with full magazine, 3 kg
Length: 500 mm
Rifling:8 grooves, rh, 1 turn in 231 mm
Sights:optical reflex, ×1 magnification, plus emergency iron sights
Muzzle velocity: SS190, 715 m/s
Projectile energy at 150 m:232 J
Rate of fire: 900 rds/min
Max combat range: 200 m
Max possible range:1,790 m