I don't know what your timeline is for finishing your essay is, but I'd suggest that you read the book "Unintended Consequences" by John Ross.
It's a fiction, but the story-line is chock full of accurate contextual references to the history and development of the modern "gun-culture".
Other than that, spend some time perusing the NRA website.
There are several different points of view on what the NRA is all about, and from gun-owner to gun-owner, you'll get any one of those different points of view.
What, more specifically, is your essay about?
Is it about the NRA, gun-owners, shooting sports, hunting, the 2nd Amendment, or...what?
:-)