The National Rifle Association (NRA) has been a well-known fixture on the political landscape for a long time. The more recent news is that the NRA spends even more money on off-the-books political advocacy (about $17.6 million) than it does on political contributions (about $1 million) and lobbying (about $3 million).
http://www.opensecrets.org/orgs/summary.php?id=D000000082
The First Amendment right of individuals to political speech is important, but the Supreme Court in Citizens United refused to uphold laws defining outer limits on mechanisms such as corporate treasuries that are used to pay for political speech. The NRA's political expenditures can be paid for not only by gun owners but by corporations that make and sell guns. The Court has also begun defining the individual right to bear arms under the Second Amendment. It remains to be seen whether there will be outer limits here as well. Does the Constitution view a hunting rifle as the same thing as an AK-47? And, as with the Court's vision of unrestrained political speech, what happens to the people who are outgunned?