It isn't.Rogue6 said:...I have no idea why the 2nd Amendment would be treated differently from the other rights in the Bill of Rights.
In 1833 in the case of Baron v. Balitmore, the Supreme Court ruled that the Bill of Rights did not apply to the states. It applied only to the federal government. However, in the late 19th century, well after the adoption of the 14th Amendment, the Supreme Court began to apply the Bill of Rights in a piecemeal fashion to the states through the 14th Amendment. This process is known as "incorporation" -- selected rights enumerated in the Bill of Rights have been "incorporated" into the 14th Amendment and thus applied to the states.
Some provisions of the 1st Amendment were not applied to the states until the 1930s and 1940s. Many procedural protections available to criminal defendants in federal court under the Bill of Rights were not available to defendants in state courts until the 1960s. Some enumerated rights, like the 5th Amendment right to indictment by grand jury, and the 7th Amendment right to a jury trial in civil cases, have not been found applicable to the states.
So far the 2nd Amendment has not been incorporated (except in the 9th Circuit). One of the difficulties in getting the 2nd Amendment incorporated is that in an 1873 case, United States v. Chruikshank, the Supreme Court ruled that the 2nd Amendment did not apply to states; and Chruikshank came after the adoption of the 14th Amendment. The 9th Circuit in recently finding incorporation distinguished Chruikshank, i. e, concluded that the facts and bases for the decision in Chruikshank (it relied on one portion of the 14th Amendment) weren't applicable in the Nordyke case before it; and incorporation was thus found based on other provision of the 14th Amendment.