An otherwise intelligent friend of mine launched a recent Facebook rant against “weapons that automatically feed bullets and can fire 100 rounds per second. I just don’t get why the Average Joe needs one. Can you explain it to me?” I couldn’t, I admitted. But I could explain that there is no hand-held gun in the world that fires that fast.

Even the machine guns mounted on military helicopters top out around 67 rounds a second, and any Average Civilian Joe caught with one of those would go straight to jail. Automatic weapons — that is, anything that fires a continuous stream of bullets as long as you hold the trigger down — are technically not illegal for civilians in the United States, but they’re so highly regulated that they might as well be.

My friend, who erroneously thinks that America is awash in machine guns that can cut somebody in two with the flick of a finger, is a good example of how the debate over so-called assault weapons perfectly embodies the lament of Supreme Court Justice Louis Brandeis when he said that “behind every argument is someone’s ignorance.”

The case for banning assault weapons — the definition is cloudy, but essentially they’re rifles that have the stylish accoutrements of military weapons, including collapsible stocks and flash-suppressors, but not the lethal automatic firepower — is being made with arguments that are practically fact-free, by a segment of politicians and chattering-class pundits who believe guns and the people who own them are innately repellent. Over and over again, they say things that simply aren’t true; they don’t bother to check the actual facts because they don’t care about the actual facts.

New York Gov. Andrew Cuomo, just to pick a random but highly publicized example, last week theatrically demanded that his legislature “stop the madness” by banning assault weapons. “It’s simple,” Cuomo said. “No one hunts with an assault rifle.”

Leave aside some relevant facts that Cuomo simply ignored: that the rate of violent crime in America is plummeting. That the murder rate is the lowest since the presidency of John F. Kennedy. That the Second Amendment doesn’t condition the right to bear arms on their use in hunting.

Just consider Cuomo’s simple factual claim: No one hunts with an assault weapon. It’s totally, absolutely, ringingly false.

“I’m not sure how many people” hunt with rifles that could be called assault weapons, says Russ Chastain, a hunter who writes a popular Internet outdoors column ( http://hunting.about.com/). But he adds: “While the percentage is low, I believe it has been growing in recent years.”

If the commercial instincts of the gun industry are to be trusted, the growth is fast and significant. The magazine Outdoor Life recently ran a comparative review of 14 hunting rifles that could be considered assault weapons and noted that “virtually every manufacturer is producing these guns.”

The idea that nobody hunts with assault weapons is undoubtedly linked to the myth that they’re like machine guns, emitting bullets in bursts that tear their targets to pieces. In fact, assault weapons are semi-automatic — that is, they fire one bullet each time you pull the trigger, a characteristic they share with practically every other gun in America. And they’re far less likely to tear big game to pieces because they fire smaller-caliber bullets than conventional hunting rifles.

“The small bullets would often cause too little damage to efficiently kill a large game animal,” says Chastain. Mostly assault weapons are used for hunting varmints, smaller animals like coyotes and prairie dogs that damage livestock or property.

Here’s what assault weapons are not used for: killing human beings. Despite the enormous and understandable publicity generated by last year’s massacre of Connecticut schoolchildren, it’s extremely rare for assault weapons to be used in murders. Of the 12,664 people murdered in the United States in 2011, only 323 — less than 3 percent — were killed with rifles of any type, according to the FBI.

That’s why a 2004 Justice Department study on the effectiveness of a federal ban on assault weapons from 1994 to 2003 concluded that the law didn’t have much impact. (Even on school shootings: the Columbine massacre took place during 1999, when the law was in effect.)

“Should it be renewed, the ban’s effects on gun violence are likely to be small at best and perhaps too small for reliable measurement,” the study said, because assault weapons “were rarely used in gun crimes even before the ban.” Unfortunately, that sentence doesn’t get quoted much, because it lacks the poetry of “stop the madness.” It’s just a fact.