|Type|| Personal Defense Weapon|
|Place of origin||Euskadi|
|Used by||Euskadiko Indar Armatuak, Ertzaintza|
|Length|| 500 mm stock extended|
350 mm stock folded
|Barrel length||180 mm|
|Cartridge|| 9x19mm Parabellum|
|Rate of fire||900–1,100 rounds/min|
|Effective range||150 m (9x19mm Parabellum)|
|Feed system||30-round plastic box magazine|
|Sights||None; MIL-STD-1913 rail provided for optics|
The Star Z-99 is a multi-caliber submachine gun developed by STAR of Euskadi as a PDW-class firearm. The base model is chambered in 9x19mm Parabellum but the weapon's modular design allows for a simple caliber conversion to either 5.7x28mm or 4.6x30mm.
The Z-99 is a modular selective fire lever-delayed blowback operated weapon (using what STAR calls a cam recoil mitigation mechanism), which contributes to the low felt recoil and allows for use with high pressure ammunition. The weapon has a conventional submachine gun layout with the magazine housed in the pistol grip. The pistol grip's backstrap and the 30-round magazine are molded from a translucent plastic which allows the shooter to quickly verify the level of ammunition visually. The receiver is machined from a lightweight aluminum alloy and most of the other components are made of a high-strength polymer to further reduce weight and costs.
The barrel and bolt assembly can be quickly replaced, converting the submachine gun to the small-caliber armor-piercingPDW ammunition.
The Z-99 is fully ambidextrous; it can be used with equal ergonomic ease by both right and left-handed shooters. Every single lever, control or toggle has been mirrored on the opposite side of the receiver – this includes the cocking handle, the fire control selector/manual safety switch (installed above the pistol grip) as well as the bolt release lever, which is used to slam the bolt closed after inserting a new magazine. The ejection port is located on the right side of the weapon.
The Z-99 has a collapsible metal stock that provides stability during aimed fire. When collapsed, the weapon is not much larger than a conventional pistol, allowing for easy handling and concealment; the Z-99 can be carried in a holster.
Two Picatinny rails are provided in the Z-99 for mounting sights and tactical accessories – one continuous rail runs across the top of the receiver and a second shorter accessory rail is installed under the barrel, in front of the trigger guard. The top rail can accommodate conventional iron sights or optoelectronic sighting devices such as reflex sights. The bottom rail is intended primarily for laser aiming modules, vertical grips and flashlights.