The 5.56 mm Kbk wz. 2005 Jantar is a Polish experimental assault rifle chambered for the 5.56×45mm NATO round. It is configured in a bullpup layout, and was designed by the state-owned Wojskowa Akademia Techniczna, based on the Kbk wz. 1988 Tantal rifle which is also chambered for the 5.56×45mm NATO round
The "Jantar" is a prototype to test the advantages of the bullpup configuration, which proved to be a more accurate layout for burst-shooting of carbines ("karabinek"). The project was not intended for production, but to gain experience to be applied in the modernisation program of the Polish military.