The NRA did a good job of promoting safety training for youth, through supervised target shooting, to get them used to handling a gun safely, and safe hunting practices. They handled the transfer of surplus weapons from the government to the boy scouts, and promoted sport shooting as a hobby.
When the urban/suburban population outgrew the rural, there also grew a segment that had no history of hunting or handling guns, who only saw them as weapons of war or criminal activity, and were generally scared of the gun's existence. From this segment came a vocal movement, mothers-against-anything-fun, along with the Friends-of-Ned-Flanders-against-murdering-cute-bunnies-&-Bambi, promoting any and all restrictions they could. More importantly they rallied the people who were ignorant of guns, other than the TV/movies depictions.
The NRA said, whoa, WTF, you're fucking with our recreation, lifestyle, and protection. That's an understandable reaction. Where they went wrong was retreating to a hilltop and building a fort, instead of infiltrating and educating their opposition. The fer me or agin me stand, seldom ends well. This case is no exception. They've created a polarization where you love guns or you're a commie, socialist, hippie, left wing, and probably a demoncrat. While the other pole thinks if you own a gun, it must be on an alter to Satan in a secret room where you eat cooked babies. I'm pretty sure most people, gun owner or not, don't fit either description.
"A well regulated militia...", when it was written, was civilians with their own guns and the skills to use them effectively, if the country needed to gather them quickly into a preplanned fighting force. It helped to have people who wouldn't shoot their eye out, or yours, when you're drafting solders to build up our military, which is the same as calling in the militia.
Whether that plan is appropriate for this day and age of professional solders, can be debated with reasonable points on both sides. But the fact remains, "...the right of the people to keep and bear Arms, shall not be infringed." is in there. So I don't see a way to outlaw them without changing the 2nd amendment. That said, the Supremes have made a couple of really bad rulings in the past,(I'm looking at you Kelo vs The City of New London
), and may again.