I've watched the NRA for years now, and I'm amazed at how far off base you are here.
While it's true that the NRA makes the mistake of often backing GOP candidates even when that candidate is more anti-gun than his Democratic opponent, they're hardly "a political tool of the GOP" (just watch how often they blast a Republican for introducing any anti-gun legislation), nor is it in any way accurate to say that that is "all" they are. You're clearly ignorant of the many activities that the NRA engages in which has nothing to do with GOP politics, or politics period.