If you don't want the mailings let them know and it will stop. When you signed up there was a box to check if you did not want the mailings and appearantly you did not check it, so you asked for the mailings.
Like someone else said they are the BIG DOG in the fight, and they have no other way to get the word out. Liberal media won't sell them time or have anything to do with them. PBS and I believe the Outdoor Channel, and the Discovery Channel (Tales Of The Gun) are the only ones that will. PBS is afraid of being charged with discrimination so they will accept NRA things.
Last word I had, a couple of weeks ago, the NRA was having over 7,000 new members sign up a day. At a recent Friends of the NRA a young GI came in and signed up both his twin boys for life membership. Another one signed up himself and his wife as life members.