NRA Sues Florida to Block New Gun Regulations

The National Rifle Association (NRA), an American organization solely focused on lobbying for the mass sale of firearms, attempted to legally block the will of Floridians, Governor Rick Scott, and the State of Florida's elected officials on today's passing of new gun regulations. The NRA claims the new law violates the Second Amendment due to the age increase of purchasing firearms, from 18 to 21. Following is the text of the United States' Second Amendment. It has zero bearing on the age requirements nor type of weapons covered by the Constitution. No mention of guns is mentioned:

"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."

How does this guarantee the age limits the NRA claims? How does it guarantee the right of someone to have and use an AR-15? It doesn't.