You know how you change the NRA? You BECOME the NRA. Remember that the NRA is an organization of gun owners. The old guard--our parents and grandparents--is disappearing and the younger generation is coming to power. The generation that grew up and served with M16's and M4's. The folks who see nothing out of the ordinary with 30-round magazines. And, the more who support the ownership and use of "high capacity" magazines who become life members, the sooner the NRA shift will be complete. The members determine the board membership and, by extension, the positions of the NRA. This ain't Bill Ruger's NRA anymore. Sitting on the outside whining about the NRA isn't going to change it. You change from within.
By all means, join GOA and SAF/CCRKBA, and any other gun group you can think of that advocates your positions to the governments of this nation. But if you think you'll be better served without the NRA, you're delusional. The NRA is our best hope to combat gun prohibitionists; and if you want them to espouse your positions, you best get on board and steer the ship.