Merely proof that “spray and pray” doesn’t work.
I’ve passed the DEA qualifier for MGs; with a little training, the benefit of full-auto is primarily being able to get faster double/triple-taps accurately.
Just emptying the mag doesn’t help with either full- or semi-auto.
Most full-auto doctrine is centered around short bursts. Holding the trigger down is movie stuff, unless you’re just spraying in the general direction of an enemy you can’t see.