Despite most of the industry showing no interest in continuing to develop firearms which chamber the 7.62x39mm, Beretta delivered a 7.62x39mm of their ARX-160 not long after the original 5.56mm. It looks like Kazakhstan may have been the first country to adopt the it. A photo from a recent military parade shows special forces carry the 7.62mm ARX-160 with the GLX-160 grenade launcher attached.
Thanks to Albi for the tip.