National Reciprocity does not violate the 10th Amendment, at least not since the 14th Amendment was passed which gave Congress the authority to enforce the Bill of Rights. Having said that, I would just love a serious 10th Amendment argument to be made (by the liberal progressives). Here is what I hope happens:
1) National Reciprocity passes (over Obama's veto)!
2) The elite statist anti-freedom anti-gunners are in a pickle. They are forced to challenge National Reciprocity in court and make a - you guessed it - 10th Amendment State's Rights legal argument (oh my the wonderful irony).
3) The panty-wetting anti-gunners succeed, National Reciprocity is declared unconstitutional as it violates the 10th Amendment and the 10th Amendment, long dormant and ignored, now has established legal precedent.
4) Meanwhile, over the several years that National Reciprocity is in place, the fears of the anti-gun bigots are proved wrong (once again) and there is ample evidence that concealed carry in New Jersey, New York City, Chicago, etc. does not present a problem. Citizens of these states demand their Second Amendment Rights and all is well in the end!
Just my .02 cents!