Why can&#39;t states require gun owners to go though Basic Combat Training under the Second Amendment?
<blockquote>
  <p>A <strong>well regulated Militia</strong>, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.</p>
</blockquote>

<p>As mentioned in the title, that tells me in 2019 that someone who can squeak through Army Basic Combat Training (aka boot camp) <strong>must</strong> be allowed to own the small arms currently used by the military.</p>

<p>What am I misunderstanding?</p>

<p>(States with strict gun control laws should love this, because they could greatly raise the bar on gun ownership, while pointing to how well they're following it.)</p>

<p>The Supreme Court considered and rejected some related interpretations in <a href="https://www.supremecourt.gov/opinions/07pdf/07-290.pdf" rel="noreferrer"><em>District of Columbia v. Heller</em></a>, 554 U.S. 570 (2008).  The entire opinion, and the dissents, are well worth reading, if you wish to get a clearer understanding of how the Court has most recently interpreted the Second Amendment. </p>

<p>A few specific comments:</p>

<ul>
<li><p>"The Second Amendment protects an individual right to possess a
firearm <strong>unconnected with service in a militia</strong>" (p. 1).</p></li>
<li><p>The Court does not agree that "militia" should be understood as synonymous with "National Guard": </p>

<blockquote>
  <p>The “militia” comprised all males physically
  capable of acting in concert for the common defense. The Antifederalists feared that the Federal Government would disarm the people in
  order to disable this citizens’ militia, enabling a politicized standing
  army or a select militia to rule. The response was to deny Congress
  power to abridge the ancient right of individuals to keep and bear
  arms, so that the ideal of a citizens’ militia would be preserved. (p. 2)</p>
</blockquote></li>
<li><p>The Court, citing <a href="https://www.law.cornell.edu/supremecourt/text/307/174" rel="noreferrer"><em>U.S. v. Miller</em></a>, 307 U.S. 174, holds that the weapons protected are "those in common use for lawful purposes".  There is some discussion on pages 55-56, in which the majority seems to explicitly deny that the Second Amendment grants a specific right to possess military weapons.  Instead, they reason that historically "the militia" would have reported for duty with the sort of firearms they normally had at home, whether or not those were the preferred weapons for fighting a war, and so therefore the Second Amendment protects the right to bear "household" weapons, not military weapons.  They seem to agree that laws banning "dangerous and unusual weapons" are constitutional, even if those weapons are in military use.  They specifically mention M-16 rifles as a type of weapon that can be banned.</p></li>
</ul>

united-states constitutional-law second-amendment