The way I understand it, the constitution preempts the states where it written as such. The 2A says the right...shall not be infringed. Now, I obviously view this in its purest reading, in that states cannot infringe on the right to keep and bear arms-period. Therefore in this case, there are no "states rights" when it comes to keep and bear...when they joined the union, they agreed to abide by the constitution and therefore "gave away" their right to "infringe".
The Supreme Court understands it differently than you do.
And that's the crux of the problem, isn't it? The result of letting lawyers parse through the Bill of Rights.