I wonder if the ammunition comes already linked for PLA,MG ammo for NATO comes linked inside the box to reduce the men hours needed at the front.
When I was a new recruit, one of my first tasks was to unlink and separate a bunch of live 5.56 rounds for C9 (M249) due to a shortage of regular rounds for rifles for a demo for Family Day. Since these were for MG, a Sergeant came and warned us "IF I SEE A F****NG TRACER GO DOWN RANGE, I WILL HAVE YOUR ASSES!"
Long story short, I can't imagine any modern military not getting linked rounds out of the factory. It would be such a waste of time and manpower and definitely lead to the complete destruction/capture of any army that had to do something so stupid.
In any case, that metal box that is feeding the MG is almost certainly how it comes delivered from the factory.