During 1973 to 1975, the Polish Military Technical Academy was working on a project to introduce a new intermediate cartridge with superior ballistics to the standard Warsaw Pact 7.62 x 39 mm, the result of which was the 7×41. Work started during 1976 on the LANTAN project, with the aim of finding a standard caliber in assault rifle/carbine/sniper rifle/LMG and belt-fed MG. The work was done by Metal Works “Archer” in Radom, as well as the Military Technical Academy in Warsaw, the Military Institute of Armament and Technology in Zielonka and Skarżysko and the Institute of Precision Mechanics in Warsaw.

There were initial ideas of doing a caseless cartridge, however the end result was a 7 x 41mm cartridge. The Lantan assault rifle was a development by Eng. Anthony Szymanski and Eng. Ernest Durasiewicza. Drawings of the new weapons were completed on the 8th of December 1977 and based on the drawings there were two prototypes made. Work on the project continued until about the third quarter of 1980 when the project was halted. Studies showed that the 7 x 41 cartridge was superior to the 7.62×39 AK, but the cost involved of the introduction of a non-standard cartridge was deemed too high.