Once you answer that question you'll also have the answer to your question. So tell me what firearm is there that is in common use that would have some reasonable relationship to the preservation or efficiency of a well-regulated militia?
Let's see. If I am part of the Well Regulated Militia, that means that I belong to a State Sponsored Militia like the SDF, Police Force and a few others. And the common weapon for them would be the AR-15, M-16 or the M-4. And you will find that the laws back that up along with the Federal Firearms laws pertaining to the sale and distribution of Automatic Weapons. You think because you are part of a bunch of yokels running around the woods wearing green pickel suits that they should get the same weapons? Nope. Only if the States and localities allows it and more and more states localities are removing the AR-15 from the allowable list. You are NOT part of the Organized Militia. In fact, the California Police have to turn in their ARs when they go off duty and go home. As does every other SDF unit.
So the answer to your question is, not all weapons used by the Organized Militia is authorized to be used in the Civilian world.
I know you won't accept that but it's the law.
nope the unorganized Militia.you and every able body man and woman are part of it.
10 USC § 311 - Militia: composition and classes
(a) The militia of the United States consists of all able-bodied males at least 17 years of age and, except as provided in section 313 of title 32, under 45 years of age who are, or who have made a declaration of intention to become, citizens of the United States and of female citizens of the United States who are members of the National Guard.
(b) The classes of the militia are—
(1) the organized militia, which consists of the National Guard and the Naval Militia; and
(2) the unorganized militia, which consists of the members of the militia who are not members of the National Guard or the Naval Militia.