But, wait....
US v Miller: "In the absence of any evidence tending to show that possession or use of a "shotgun having a barrel of less than eighteen inches in length" at this time has some reasonable relationship to the preservation or efficiency of a well regulated militia, we cannot say that the Second Amendment guarantees the right to keep and bear such an instrument. Certainly it is not within judicial notice that this weapon is any part of the ordinary military equipment, or that its use could contribute to the common defense. Aymette v. State, 2 Humphreys (Tenn.) 154, 158."
United States v. Miller
Now, we CAN show that a select fire, or semi-auto firearm DOES HAVE a reasonable relationship to the efficiency of a militia...
And, under 10 US 311, we ARE the militia so....we all need these select fire weapons, as well as Homeland (in)Security.