i used maya in mine i importet my m249 as a obj to maya and then i importet the assault rifle as a FBX in to maya and puttet my m249 in the same position as the assault rifle then i unbindend the skin and delete only the assault riffle mesh and then i selected all the bones and binded it to my m249 and after that i weight paintet my m249 on the assault rifle inj root(white) and paintet the rest of the bones black after that i exportet it out as a FBX and importet it to ADK and chosed the assault rifle skeleton in the mesh in the import options