21

The depiction of guns in movies is, famously, not very exact. (Guns are cocked dramatically a thousand times over and safety standards don't even seem to exist).

However, one aspect I was wondering about is the (in)famous silencer: Transforming a loud -bang- into a small "pew pew". (For examples, check the first scene from "Sin City", where the narrator even comments on the gun being turned into "a whisper" by the silencer). This would mean that a gunshot gets reduced from about 150 to 170 dB to around 20 to 40 dB. Now this, in movies, is always achieved by a simple metal tube screwed on top of the gun.

Now, as someone who does not live in the US and doesn't know a thing about guns, I was wondering: Can a gun be silenced to a level of about 40dB?

  • It seems that it is at least possible to construct a silent gun. According to this article: smithsonianmag.com/history/…: "While President Franklin D. Roosevelt was busy (...) Donovan fired ten rounds into the sandbag. FDR gave no notice and never stopped talking (...)". However I would assume that building a silent gun is rather different than silencing an existing gun. – Eike Pierstorff Jul 1 '15 at 10:25
  • @EikePierstorff - It's not possible unless the bullet is subsonic. The noise of the bullet breaking the sound barrier is not "silenced" (nor can it be). – Mayo Feb 27 '18 at 16:40
21

Evidence that movie gun silencers are not as effective as stated is all over the Internet.

According to Wikipedia:

Live tests by independent reviewers of numerous commercially available suppressors find that even low-power, unsuppressed .22 LR handguns produce gunshots over 160 decibels. In testing, most of the suppressors reduced the volume to between 130 and 145 dB, with the quietest suppressors metering at 117 dB. The actual suppression of sound ranged from 14.3 to 43 dB, with most data points around the 30 dB mark. A notable example is the De Lisle carbine, a British World War II suppressed rifle used in small numbers by Special Forces. This was recorded at 85.5 dB in official firing tests.

  • 2
    Note that dB is logarithmic scale, thus reduction by 30dB is reduction of acoustic power 1000 fold. – vartec Jun 26 '14 at 15:53
  • 3
    But also note that 140dB is the noise level of a rocket launch or standing next to an airplane engine. – Twinkles Jun 27 '14 at 8:42
8

There are two parts to consider here: silencing the report (exhaust) of the gun itself and silencing the disturbance the bullet makes.

The bolt-on silencer can be effective in reducing the noise the gun makes[1] but nothing will affect the bullet's noise. There's action noise as well, but this isn't much and can go away completely by using a manual bolt action. Subsonic rounds like a .22 short can thus be fairy quiet, but a Barrett 50 cal will wake most of the downrange neighborhood even if you bury the barrel in several mattresses.

If you really want to muffle things up, use a small non-revolver, tape a couple of pillows around it and hold it up to the target. Won't be silent, but the people in the next room will say "what's that?" rather than know exactly what it is.

Oh, and the thing on the front of the Barrett isn't a silencer - it's a muzzle brake. It catches and redirects the gases backwards to reduce the recoil to the point where it doesn't shatter the user's shoulder.

[1] and "by" 40 db is far more realistic than "to" 40db, which is about the amount of noise a busy computer's disk drive makes. Only way a gun is going to be that quiet is if you don't fire it.

  • 6
    Any references to support your claims? – Nate Eldredge May 2 '14 at 12:48
  • What if shooting is done point blank, where end of barrel touches the body? – Matas Vaitkevicius Jul 2 '15 at 11:50
5

The short answer is not really.

The longer answer is that, while a silencer (aka suppressor) does dramatically reduce the report of a handgun, the sound of the pistol doesn't universally transform into the audio clip that has become a movie standard (some would say cliche).

The Mythbusters tried this one as part of their "Sounds Bogus" episode dealing with movie audio versus real-world sounds. They called their results "plausible" due to the reduction in sound level, but did state that the sounds they recorded did not match the movie sounds. Here's the digest of that myth including what silencers really sound like on "defense-caliber" pistols.

https://www.youtube.com/watch?v=zhdXly6jT4E

The trademark "silenced pistol shot" sound in most movies is usually some variant on a suppressed .22 target pistol. That pistol is stereotypically common in the hands of close-in assassins (another movie myth; anyone who could get close enough to be lethal with a 22 has many better options) and therefore the sound it makes has become associated with all silenced pistols.

  • Note that a silencer and a suppressor aren't the same thing: a suppressor muffles the gun itself, while a silencer slows the bullets. A supersonic bullet makes a mini sonic boom, a silencer is meant to prevent that. Of course, some combinations of guns, barrels, and bullets are subsonic without a silencer. – user3150 Jun 30 '15 at 12:58
  • Where'd you hear that? A suppressor is a silencer, it reduces muzzle flash and report of the weapon firing (and for lighter weapons like pistols it reduces recoil and muzzle climb due to the increased weight out front). The bullet might be slowed by friction through the extended barrel without the aid of the gas pressure which is being dissipated, but that's incidental. To minimize the sonic boom of supersonic muzzle velocities, you have to use rounds specifically designed to be subsonic; the silencer/suppressor is not designed to help with that. – KeithS Jun 30 '15 at 15:20

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .