A man walks into a nightclub with an AR-15. It is similar to the weapon I was trained on in the Army. It was designed for combat, to kill as many of the enemy as possible in the shortest amount of time. I was pretty good with it, even earned a marksmanship badge, but when the training was over and we returned to the barracks, our weapons were placed in their racks and all bullets were taken from us. Once, a somewhat goofy member of my platoon slipped a round into his pocket. We all felt unnerved. What did he have in mind?

Now, an even more lethal version of that weapon is readily available on the market. If you told me back in my Army days that I could have bought the same weapon that I had been using in training, I would not have believed it. You might as well have mentioned a tank or a bazooka or a Bangalore torpedo, a handy bit of explosive useful for shredding barbed wire. And yet, this is what I get when I Google “AR-15”:

“Not sure what type of AR you want to build? Look through our AR-15, AR-10 and other AR rifles available, all at great prices at Grab A Gun. Buy Today.”

One is available for $483.18. Maybe you get it for less if you buy two.

But it only took one — plus a handgun — to kill dozens of people at the Pulse club in Orlando. The shooter was mentally deranged. He was Muslim. He was born in New York. He had been married and he hated gays and he saw them kissing and he was nauseated by the sight … . The details intrigue and overwhelm and make this atrocity seem different from the previous ones, of which there are now so many. But it is always the same. It is always about guns.

At moments like this, two people pop into my head. The first is Wayne LaPierre, the executive vice president of the National Rifle Association. He has said that Americans need assault weapons, lest “jack-booted government thugs … break in our doors, seize our guns, destroy our property and even injure or kill us.” How he left out the rape of our virgin women, I shall never know — probably an oversight.

The NRA has led the way in the mainstreaming of a demented gun ideology. It has been aided by a severe reading of the Second Amendment, which represents the thinking of 18th-century men and their desire for a militia. They were not infallible. They countenanced slavery (some of them were slave owners) and the disenfranchisement of women, and they created that undemocratic concoction called the Electoral College by which a one-vote margin is tantamount to a landslide.

My second person is Ralph Nader. He is much vilified now for his 2000 presidential run that may have cost Al Gore the presidency, but before that he took the American automobile industry to task for the cars it made. He argued that you could hector people to drive safely until the cows came home, but accidents would happen anyway. Some people would speed. Some would run lights. Some would drink and now they would text. So you had to design a car to withstand a crash. You have to save people from themselves.

It is the same with guns. Some politician will say we have to do something about mental health. (Hah! We can’t even keep nuts from running for president.) The one thing we can do something about is guns. Leaving aside handguns and hunting weapons, what’s the justification for possessing an AR-15? What’s the justification for a semi-automatic weapon with a magazine of 30 rounds? A shooter can get off 30 rounds in about half a minute. Pop in another magazine and that’s another 30 rounds. In a crowded space, it can take less than a minute to shoot 50 people.

So, let’s go back to that rifle range at Fort Dix, New Jersey. I have just earned my marksmanship badge and, accordingly, I get a weekend pass. I rush back to the barracks, shower and change into civilian clothes. As I bolt out the door, my platoon sergeant, the thoroughly intimidating Peter Grande, by actual name, hands me my rifle and says I can take it with me for the weekend. Absurd, you say. Not as absurd as this: Nowadays I could say, “Thanks, Sarge, but I already have one at home.”

Richard Cohen is a columnist for The Washington Post. His email address is: cohenr@washpost.com.