In full auto, or 3-round burst the M4 is a class III item. You can have one in some states after paying a tax to the BATF and going through considerable trouble.
You can, in many states, own an AR that resembles the M4 exactly, but is semi-automatic (1 shot per trigger pull) and must have a barrel length that is a minimum of 16”. Much more economical, and just about as much fun.
Definitely multiple burst per squeeze. That was incredible. Did really well with the M4 but dont know if that counts, considering the red laser probably cant miss.