A gunman in a high-rise hotel overlooking the Las Vegas Strip opened fire on a country music festival Oct. 1, in the deadliest mass shooting in modern American history. (Taylor Turner/The Washington Post)

In the wake of Sunday night’s mass shooting in Las Vegas that left at least 58 people dead, the attention of those advocating for stricter gun control laws seized on a current debate in Washington. The Hearing Protection Act, sponsored by Rep. Jeff Duncan (R-S.C.), would allow more people to purchase silencers for firearms — which, some argued, would have made the shooting in Vegas much deadlier.

Among those making that case was Hillary Clinton. “The crowd fled at the sound of gunshots,” Clinton wrote on Twitter. “Imagine the deaths if the shooter had a silencer, which the NRA wants to make easier to get.”

But the effect of having a silencer probably would have been negligible. Clinton and others appear to be assuming that silencers — or “suppressors,” as they’re known in the industry — work the way that they do in the movies. Screw a little barrel on the end of your pistol, and you can run through enemy headquarters picking off bad guys with no more audio footprint than a little zip.

In reality, trying to suppress an automatic weapon sounds like this.

The gunfire is clearly audible, as our Washington Post fact-checkers noted in March.

The video above features a weapon from Asymmetric Solutions, a firearm training firm based in Missouri. Thomas Satterly, the company’s director of development, spoke by phone with The Post to explain why a suppressor wouldn’t have silenced the noise of the gunfire in the way Clinton assumed. Satterly is a veteran who served in Somalia in 1993. When we spoke, he was with several friends who served in law enforcement and who contributed their thoughts, as well.

“A suppressor wouldn’t have stopped anyone from doing what they did” in Las Vegas, Satterly said, “and definitely wouldn’t have hidden the noise of the gunfire.”

A suppressor, he explained, is used to try to hide the location of a shooter by both lowering the sound of the shot and hiding the flash while firing a round [which helps hide location and preserve the shooter’s night vision]. You can still hear the shots, as above, but by making it quieter, locating the shooter becomes more difficult. (In Vegas, he noted, the echoes of the gunshots would have done a much more effective job of masking the point of origin.)

Satterly also notes that the actual gunshot — the pin hitting the ammunition — is only one source of sound. Another sound comes from the bullet breaking the sound barrier as it approaches its target. That’s not affected by a silencer. In this video — which is loud — you can see the use of subsonic ammunition that travels slower than the speed of sound. Even with a suppressor and subsonic ammunition, the gunshot is still audible.

Those Hollywood scenes in which James Bond takes out a dozen enemies as he makes his way to his target is wrong for another reason: Suppressors don’t last forever.

“Back in the day, when we had silencers … you could screw a brand-new silencer on a weapon, and maybe the first two rounds were really suppressed,” Satterly said. “Once you shoot the baffles out” — the rings of rubber that absorb energy in the suppressor — “the sound is almost the same.” As you shoot, in other words, the suppressor loses its effectiveness. Satterly was referring to a handgun, not an automatic weapon. An automatic weapon creates so much heat that it rapidly deteriorates the effectiveness of sound suppression (or simply melts it).

Using a suppressor also changes the effectiveness of the weapon. Firing through a suppressor reduces accuracy. Subsonic ammunition reduces range (because the bullet travels more slowly).

The shooter in Las Vegas fired on a concert from a hotel across the street. Satterly noted that a more effective means of suppressing the sound of those shots would have been to simply stand farther back in the room, letting the sound be absorbed by the room itself instead of escaping in all directions outside the window.

As Satterly pointed out, then, allowing the use of suppressors more widely probably wouldn’t have made the tragedy in Las Vegas much worse.

“I can definitely say it wouldn’t have changed anything,” he said. “It wouldn’t have hidden the sound enough. Again: That’s just Hollywood.”