Then why does the 2nd amendment specifically mention it? "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed." The founders didn't believe in standing armies. Each state had its own militia. Now we have a large standing Army, Reserves, and National Guard. The National Guard is the "well regulated militia" of today. Military troops are not allowed to carry their assigned weapons around town or even on military bases. What business does Joe Blow, who is not in the Military, National Guard, or law enforcement have carrying or owning military grade weapons?
(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.
10 USC § 311 - Militia: composition and classes | LII / Legal Information Institute
What business does Joe Blow, who is not in the Military, National Guard, or law enforcement have carrying or owning military grade weapons?
To defend against the government if it created laws that would create a dictator.