The decision did not revoke all the states' rights to regulate guns.
"The majority decision also reaffirmed that certain firearms restrictions mentioned in District of Columbia v. Heller are assumed permissible and not directly dealt with in this case.[24] Such restrictions include those to "prohibit...the possession of firearms by felons or mentally ill" and "laws forbidding the carrying of firearms in sensitive places such as schools and government buildings, or laws imposing conditions and qualifications on the commercial sale of arms".[24]" McDonald v. City of Chicago - Wikipedia McDonald, at ___-___ (slip op., at 39-40)
"Even the NRA concedes that you can’t have mad men running around with weapons of mass destruction. So there are some restrictions that are permissible and it will be the task of the legislature and the courts to ferret all of that out and draw the lines. I am sure, though, that outright bans on handguns like they have in D.C. won't be permitted. That is not a reasonable restriction under anybody’s characterization. It is not a restriction, it’s a prohibition.[66] " McDonald v. City of Chicago - Wikipedia Interview: The Way of the Gun, Leigh Ferrara, MotherJones.com, April 19, 2007
So, the point of referencing McDonald v Chicago was that the case was centered around the idea that State Law can't supersede the Federal (see also Pennsylvania v. Nelson). The States aren't prohibited from all ability to regulate guns because (as the Supreme Court understands it) the Federal government is not either. So because the federal can ban possession of felons a State can as well. But by that notion, if the Federal doesn't limit it based on age, the State cannot either. But all and all, this part of the McDonald v Chicago decision has nothing whatsoever to do with your initial point in response to me.
More to the point, your initial assertion is that states rights and the 10th somehow gives a State power to regulate a right the federal cannot, which the McDonald vs. Chicago ruling shows is not the case, and the exceptions laid out in that ruling do not in fact make any allowances for the States to overrule Federal law on the grounds of the 10th.
If it is as you say, if it is the case that the States can violate the rights of the constitutions because of the Tenth Amendment, I wonder how on earth the Supreme Court was able to rule that a State could not ban gay marriage due to the Federal Constitution... If your argument about the Tenth holds water, just how exactly did that happen?? Shouldn't the Tenth, by the way you describe it, allow a State government to prohibit same-sex marriage even if doing so violates the Constitution??
Ah, but of course, the Tenth doesn't work that way at all. Obergefell v. Hodges clearly shows that the State governments cannot violate a constitutional right, one of many rulings to do so.