 In the early 1990s, as part of their preparations to join NATO, the Polish armed forces began looking for a replacement for the PK-series machineguns they had in service.Cegielski proposed a prototype (code-named PKM-NATO) that modified the PK/PKS to feed standard 7.62×51mm NATO cartridges and use NATO-standard ammo belts.The modifications included a heavier barrel, a larger chamber, and a redesign of the lock, extractor, and the entire feeding mechanism.