Skbk wz . 1989 Onyks The 5 . 45 mm subkarabinek wz . 1989 Onyks is a lightweight Polish carbine variant of the 5 . 45 mm wz . 1988 Tantal assault rifle , also based on the AK ( S ) - 74U Work on the weapon began in 1989 at the " Ośrodek Badawczo - Rozwojowy " state research institute in the city of Radom . The weapon ’ s technical specifications were confirmed that same year . It was not until 1990 that production approval was given for the first prototypes , evaluated the following year in a series of military qualification tests resulting in an order for an initial pre - production batch in 1993 , to be manufactured at the Łucznik Arms Factory in Radom . The carbine was created by a team led by B . Szpaderski and it ’ s chief engineers were K . Styczyński and E . Wysocki . The Onyks remained a prototype and has never advanced past the research and development stage . The Onyks was designed to equip airborne infantry , police and military special operations units and vehicle crews . Design details . The carbine has an identical design layout , system of operation , locking mechanism and uses the same type of ammunition as the Tantal rifle , and the main modifications include the following components : the barrel , bolt carrier and piston rod , gas cylinder , foregrip , heatguard , muzzle device and iron sight s . Compared to the Tantal , the Onyks features a barrel reduced in length by , fitted with a different type of muzzle device . Due to the to barrel ’ s length , this device is primarily used to reduce muzzle flash , but it can also be used to mount and launch rifle grenade s . At its muzzle end , the device has a conical flash hider , and on its tapered , external surface – a retainer spring and two collars , used to attach and guide rifle grenades . The Onyks features a bolt carrier borrowed from the wz . 1988 rifle , but with a significantly shortened gas piston rod . Additionally both the gas cylinder and upper heatguard have been reduced to accommodate the short gas system . The carbine also has a different sighting arrangement than the Tantal rifle , with a newly designed rear sight . The open - type flip sight with both 100 - 200 and 400 m settings is installed at the rear of an extended sight rail protected by ears , which is riveted to the rear sight base . The sight has two settings , “ 1 i 2 ” and “ 4 ” ( that correspond to firing ranges from 100 to 200 m and 400 m respectively ) . The flip sight locks in position with a spring detent . The adjustable front sight post is screwed into the front sight base that is installed in the gas block . The Onyks can be fitted with tritium night sights , similar to those used in the wz . 88 Tantal . Recesses cut into both sides of the sight rail are used to mount optical sights . The wooden or synthetic handguard , designed specifically for the Onyks is installed in a way analogous to the Tantal rifle ’ s handguard . The carbine is supplied with three spare magazines , four 15 - round stripper clips and a magazine guide , cleaning kit , cleaning rod ( which is stored in the maintenance kit , unlike the Tantal – under the barrel ) , sling , accessory pouch and oil bottle . Also unlike the Tantal , the Onyks is not compatible with a bayonet , bipod or the 40 mm wz . 1974 under - slung grenade launcher .