A belt loaded spinwheel machine gun, where there are some chances the next bullet is a dummy round, or goes in the wrong direction. And everytime you reload a new soldier is in charge of the gun

You don't need that analogy as the normal use of a automatic gun in war is not to kill, it is to suppress - stop the enemy from moving. If you are hit by a gun in automatic mode it is your own stupid fault. When you want to kill someone you switch to one shot or maybe 3 round bursts.