I actually know a lot about guns. I've had them around since I was a kid, I was in the military, I belong to a rifle range, was a long-time hunter (though I quit a few years ago.) With a few exceptions, most gun-range sports (target shooting) can be practiced with low-energy, low-rate-of-fire weapons. The exceptions would mostly be combat simulations. But why protect those sports in which the very purpose is to simulate killing others?
Some gun sports, like hunting, require heavier weapons -- but not high rate-of-fire weapons. It's a hunting truism (and I was a hunter for decades) that if you have to fire more than twice, you're almost certainly going to miss the target that you missed the first two times, and worse, you've probably shooting in haste, which is when you hit unintended targets, like other hunters. There are exceptions, of course, but most ethical hunters don't take multiple shots at a single target.
But here is a "constitutionalist" argument about guns -- the framers of the constitution didn't care about shooting sports. The reasons the people should be armed was for the very reason that they might be necessary to create an effective militia, whose purpose would be to kill people. In other words,what the framers were really protecting was the 18th-Century assault rifle.
But that's not all they did -- they also gave the government to regulate the militia. The Second Amendment reads, "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed." Therefore, the federal government has the full right to regulate their militia. If I were king of the US, I would say that the potential militia man must arm himself with a .308 bolt-action rifle, and furthermore, must report for a month of physical training each year: essentially, a month of Marine Corp physical training under the eye of Marine drill instructors. That should thin the militia herd considerably.
As far as the photos were concerned, I think they deliberately cast a lot of the photos with that kind of here-but-crazy look that Arbus specialized in. I started shooting when I was a kid, on an Iowa acreage, under close supervision of my father and an uncle. Do you see any adult supervisors in those photos? I think if you did, they would be much less unsettling. It's the small-child with big-gun vibe that makes you nervous.
