Silencer or Suppressor
by Kirk Lawson
In 1908 Hiram Percy Maxim filed patent for what he called a "Silencer." Hiram Percy had firearms inventing in his blood. His father was the firearms inventor made famous for, among other things, inventing the Maxim Machine Gun. At about the same time, Hiram Percy invented a 'silencer' for the internal combustion engine, which we now call a "muffler." His purpose in both was to reduce the great noise made by a contained combustion and to make a ton of money selling his inventions. Today Hiram Percy Maxim's "Silencer" is now more often called a "Sound Suppressor" or just a "Suppressor."
[So how does it work?]
Most modern firearms Suppressors use the same concept that Hiram Percy Maxim's original did. A tube is affixed to the muzzle of the barrel with a exit port for the bullet. The diameter of the tube is significantly larger than the diameter of the barrel to make room for multiple chambers into which the combustion gasses can expand and attenuate. When a gunshot is fired there are two things which cause the very loud noise. One is the bullet itself compressing the air in front of it and breaking the sound barrier. Yes, bullets often create a Sonic Boom which is at least as loud as the cracking of a Bullwhip, which also creates its loud crack by the "popper" of the whip breaking the sound barrier. The other thing which makes the loud bang when a gunshot is fired is the rapidly expanding combustion gasses causing a compression wave in the open air, more commonly known as a "sound wave," when it exits the muzzle. By allowing much of these gasses to expand into chambers in the Suppressor tube, some of the force of the compression wave can be diverted. It is impossible for this process to completely remove the compression wave because some of the rapidly expanding gasses are going to exit behind the bullet, regardless. So even when a Suppressor is used to mitigate the noise, there still is a "left over" compression wave which can be very significant, on top of a Sonic Boom created by the bullet.
[So how effective are "silencers?"]
Most of us are aware that decibels are a method of quantifying noise levels. It's named in honor of Alexander Graham Bell and is used for a bunch of technical stuff that we don't really care about in this context. An important distinction about decibel sound levels is that the quantification is logarithmic. To keep it simple, basically, doubling the number means increasing the intensity by 10. So a decibel level of 10 would have a power ratio of 10 where a decibel level of 20 has a power ratio of 100, which is 10 times greater. It is not a linear progression. Any time the number grows larger it grows a LOT larger! This is very bad for human hearing. According to the U.S. Department of Health & Human Services, National Institutes of Health, "...long or repeated exposure to sounds at or above 85 decibels can cause hearing loss. The louder the sound, the shorter the amount of time it takes for [permanent hearing damage] to happen."
According to the American Speech-Language-Hearing Association, here are some decibel noise level comparisons.
150 dB = fireworks at 3 feet
140 dB = jet engine
130 dB = jackhammer
120 dB = jet plane takeoff, siren
110 dB = maximum output of some MP3 players, model airplane, chain saw
106 dB = gas lawn mower, snowblower
100 dB = hand drill, pneumatic drill
90 dB = subway, passing motorcycle
80-90 dB = blow-dryer, kitchen blender, food processor
70 dB = busy traffic, vacuum cleaner, alarm clock
So what is the decibel level of a 9mm, the most commonly used self defense pistol caliber in the U.S.? According to M1911.org, it is 160 dB. It is louder than a jet plane taking off and louder than a jackhammer. Even the lowly, "quiet," .22 Long Rifle is 136 dB. And remember, decibel measurements are logarithmic, not linear. A 9mm is 1,000 "louder" than a jackhammer.
So how much noise does a "Silencer" knock off of a sound impulse? On average a "Silencer" will reduce the noise by about 30 dB. So a "Silenced" 9mm will be as whisper quiet as a jackhammer and a "Silenced" .22 Long Rifle will be the hushed tranquility of a lawn-mower. I hope you don't mow your lawn early in the morning because that stuff is so loud that it wakes up neighbors.
Therefore, honestly, while a "Silencer" does reduce the noise level very significantly, it is no where near "silent." Never mind near, it's not even in the same time zone. Even a "silenced" .22 is so loud that it can cause permanent hearing damage (greater than 85 dB).
[So why do people think "silencers" turn guns into Silent Death Machines?]
Well, to be fair, Hiram Percy did name it a "Silencer" and then proceeded, in typical early-20th Century fashion to exaggerate the effects and use it as a marketing ploy. He was, after all, a business man.
But that was more than a century ago. There's been plenty of time for the marketing hype to fade and be replaced with reality. Nevertheless the legacy media, Senator Kirsten Gillibrand, and Senator Chuck Schumer continue to insist that "silenced" handguns will allow assassins to circulate freely in society, murdering at will, and no one will be able to hear their nefarious homicides. If they didn't get their information from the U.S. Department of Health & Human Services, National Institutes of Health, the American Speech-Language-Hearing Association, or any other of the many respected and authoritative sources, where did they get their information from?
[So what's all the stink about the "Hearing Protection Act?"]
In 1934, partially as a result of highly publicized violence of Organized Crime, the National Firearms Act was passed. Among other things, it regulated "Silencers" or sound suppressors. In short it required a special license issued to own a "silencer." This cost $200 and required paperwork to be submitted and approved by what is now the Bureau of Alcohol, Tobacco, Firearms, and Explosives (BATFE). Two-hundred 1934 dollars is the equivalent of $3,733.53 in 2017 dollars and was deliberately intended to be cost prohibitive to anyone who's last name wasn't Vanderbilt or Rockefeller. Even today, $200 can increase the end cost of the firearm from between 20% and 100% or more. And that's just including the licensing fee, but doesn't account for the actual price of the suppressor. Even after the prospective suppressor owner has paid the $200 "Tax Stamp," it can often take a very long time for the BATFE to approve the purchase. 3 month waits are not uncommon and even 12 month waits are not unheard of.
H.R. 367, the Hearing Protection Act of 2017, aims to deregulate the sale of Suppressors, removing them from the restricted list and junking the $200 licensing fee. Just because a Suppressor doesn't completely eliminate the damaging sound impulse doesn't mean that a Suppressor doesn't mitigate some of it. This is particularly important to people who may not be able to use secondary hearing protection, such as plugs or muffs. This includes hunters who need to be able to hear their environment, people using guns for self defense inside the home, trainers, competitive shooters, and many more.
It also does not escape the attention of many Suppressor advocates today that in much of gun-adverse Europe that the use of firearms sound-Suppressors is often considered the polite thing to do. In some cases is it actually required.
There has also been a lot of ink, both actual and digital, spilled over the fact that a firearms user can (and should) wear independent hearing protection such as ear-plugs or ear-muffs. While true, it should be noted particularly that the Centers for Disease Control and Prevention, in a 2011 study (despite false claims that the CDC can't research guns & health), concluded that the best way to protect everyone from gunshot-related hearing damage was to use sound suppressors.
Many, including myself, consider it to be technically correct to refer to a firearm sound Suppressor as a "Silencer" because that is what Hiram Percy Maxim named his muffler-for-a-gun. Nevertheless, the concept that one makes the gunshot into a "silent" click is a myth perpetuated by the unfortunately ignorant or by people with an agenda.