For the quietest suppressed shooting experience, we all know that subsonic ammunition is a must. Preventing the projectile from breaking the speed of sound prevents the projectile from making a sonic boom. Yes, just like a fighter jet, a bullet breaking the sound barrier generates a loud crack!!! as it flies downrange at supersonic speed.
When shooting unsuppressed, the difference in nearly all cases is difficult or impossible to hear. Subsonic or supersonic, the gunshot sound itself is so darn loud that it drowns out any sonic boom made by the bullet exceeding the local speed of sound. Throw a silencer on, however, and now the gunshot sound is suppressed so heavily that the difference between subsonic and supersonic ammo is drastic. Much larger than most of us would suspect.
Now, with many cartridges there’s also a difference in how much gunpowder is used. For example, one cannot load a heavy enough projectile into a .223 Remington to use effectively the same powder charge but cut the velocity by so much that the projectile is subsonic.
However, the velocity of some cartridges is so close to the speed of sound already that simply moving up or down in bullet weight is all that’s necessary to switch from supersonic to subsonic, or vice versa, without any change in the powder charge.
In the video embedded above (or click HERE to view it directly on Rumble), we chose one of those cartridges — your standard 9mm pistol cartridge — to demonstrate the sound difference between subsonic and supersonic ammunition, because bullet weight is the only variable that’s changing. There’s no difference in the actual noise of the gunshot, since it’s the same amount of gunpowder and same amount of pressure, etc., behind the bullet.
With a heavy, 147 grain bullet the “oomph” contained in the gunpowder isn’t sufficient to fire the bullet fast enough to exceed the speed of sound. With a lightweight 115 grain bullet, it is enough “oomph” to fire the bullet at supersonic speeds. And that supersonic crack or lack of it, my friends, is the sound difference you hear in the video.
Note: it is significantly more pronounced in real life. While the video provides an idea of what it sounds like, the microphone and the camera and your speakers or headphones simply cannot reproduce it realistically. In part because the supersonic gunshot is louder than your speakers and, in all likelihood, louder than the microphone or camera will allow. In many cases the subsonic shot is, too, but either way what this means is that the difference between the two is being compressed.
Nerd note: air temperature is by far the biggest independent driving factor in your local speed of sound. Use THIS CALCULATOR to figure out the speed of sound where you are based on the temperature outside.
Personal nerd note: with some 9mm and .22 LR loads, the speed of sound straddles the bullet’s velocity such that I’ve been out on the range shooting suppressed where every shot was supersonic in the morning in 30- to 40-degree temperatures (the speed of sound is ~1,090 FPS at 35 degrees) and every shot was subsonic in the afternoon in 60- to 70-ish-degree temperatures (the speed of sound is ~1,128 FPS at 70 degrees). Example: if the bullet travels at 1,110 FPS (which is typical of many 9mm and .22 LR loads) it’s faster than the speed of sound at 32 degrees air temp but slower than the speed of sound at 72 degrees air temp.
Good advice.
However; loading a heavier projectile with the same propellent load will increase the deflagration velocity of the propellent. The powder will burn faster. On longer barreled pistols and carbines, you just might gain velocity on a load that uses slower burning propellent.
After shooting several suppressed pistols, carbines and rifles, I am wishing that I had gotten me some before Senile Sock Puppet Biden and Cameltoe Harris staged their coup.
If you want to go through the paperwork and expense suppressors are cool. But, no thanks. Too much sugar for a dime
Besides, they aren’t that quite. Except for an MP-5SD. Those were really cool. Anyway, I didn’t have a choice. They just stuck it my hands and said, “Go shoot.”
“Throw a silencer on, however, and now the gunshot sound is suppressed so heavily that the difference between subsonic and supersonic ammo is drastic. Much larger than most of us would suspect.”
I can attest that this is absolutely true. I know someone who has an AR platform pistol with something like a 9-inch barrel chambered in 9mm Luger and a quality suppressor. He shot cartridges loaded with 115 grain bullets which were supersonic and it was LOUD–bordering on painful when I was standing 70 feet behind him and not wearing hearing protection. It was so loud, in fact, that I thought he was shooting without the suppressor.
When he shoots that same platform with subsonic ammunition, the sound which the the bolt generates from slamming backward and forward from each shot (e.g. the action cycling) is louder than the actual gunshot. That is a HUGE difference.
Well how about that.
To bad a person just cant walk into and walk out of a store with a suppressor no paper work involved.
I’d like to see a ballistic gell test of the difference in bullet preformance.
Possum, in 10% ordinance gelatin the difference in performance is significant. You may as well shoot ball.
That’s kinda what I figured
It isn’t that simple. In 9mm, for example, where bullet weight determines supersonic or subsonic, there’s really no performance difference due to that velocity change. In fact, most LE and self-defense loads have gone to heavy-for-caliber bullets for the most reliable penetration and barrier penetration performance. 147 grain loads have become the norm for self-defense 9mm and it’s effectively all subsonic. I’ve been carrying 147 HST for many years and my carry guns aren’t suppressed. Supersonic/subsonic simply has no relevance to bullet performance in these sorts of cases where it’s basically the same amount of powder energy either way and you’re just changing the bullet weight. What you’ll see in ballistic gel is that heavier bullets tend to penetrate more deeply, deviate off course less, and many hollow points will actually expand to a larger diameter because there’s physically more bullet to do so (heavy bullets being larger — longer — than lighter bullets in a given caliber).
In the case where you’re reducing the powder load to artificially slow the projectile down (subsonic .308, subsonic .223, etc) then, yes, you absolutely hurt terminal ballistics.
It’s not the same amount of powder. The 147gr bullet limits the space for powder. 115gr is 4.9-5.7gr of WSF. 147gr is 3.7-4.3gr of WSF. In a rifle load, a grain difference is a small fraction. Here, the 115gr holds 32% more powder.
I do have a couple suppressors I use on a PCC and on 1 of my pistols, but, not something I can’t live without. Although I have been considering getting a suppressor for 1 of my AR10 rifles. Keep the report slightly muffled when hog hunting. Might be able to get another pig or two before the herd is scared off from the noise.
They can hear a twig snap.
“Nerd note: air temperature is by far the biggest independent driving factor in your local speed of sound. Use THIS CALCULATOR to figure out the speed of sound where you are based on the temperature outside. ….
Personal nerd note: with some 9mm and .22 LR loads, the velocity straddles the speed of sound so closely that I’ve been out on the range shooting suppressed where every shot was supersonic in the morning in 30- to 40-degree temperatures (speed of sound ~1,090 FPS at 35 degrees) and every shot was subsonic in the afternoon in 60- to 70-ish-degree temperatures (speed of sound ~1,128 FPS at 70 degrees).”
More magic laws-of-physics-violating bullets? Seriously? I was not aware that Harry Potter made bullets at the Hogwarts ammunition manufacturing plant.
Your “experience” for “30- to 40-degree temperatures (speed of sound ~1,090 FPS at 35 degrees)” vs. “in 60- to 70-ish-degree temperatures (speed of sound ~1,128 FPS at 70 degrees)” in regards to “supersonic” vs. “subsonic” – has nothing to do with the “speed of sound” vs. temperature
Unless the temp is many degrees below 32 °F or many degrees above 68 °F degrees you will not see a temperature effect on bullet velocity at less than 100 yards that causes a bullet to change velocity by 38 FPS which is what you are claiming.
The range 32 °F – 68 °F is considered as “normal conditions” for measurement of sound and applies to in open air only.
modern day ammunition “power charge” is designed to be stable within a certain temp range and all of them include 32 °F – 68 °F in that range – meaning the “powder charge” in the bullet is going to provide the same amount of energy at 32 °F as it does at 68 °F. Which means a bullet that fires at supersonic velocity is going to fire at supersonic velocity and a bullet that fires at subsonic velocity is going to fire at subsonic velocity – a bullet can not fire at both subsonic and supersonic velocity which is what you are basically saying.
At 20 °C (68 °F), the speed of sound in air is about 1,125 ft/s — At 0 °C (32 °F), the speed of sound is about 1,086 ft/s —- Note the words here “in air”.
For a bullet to fire at subsonic velocity has nothing to do with the bullet being “in air”, it will fire at the greatest amount of energy it will ever have in the barrel at the muzzle velocity point which is the point where it leaves the barrel and has not at that point encountered enough “in air” volume to affects its velocity – it can not speed up to supersonic velocity at one outside in air temp and then slow down to subsonic at another outside in air temp. You can not add energy to a bullet once its fired to make it speed up – energy can neither be created or destroyed. For a subsonic velocity to increase to supersonic velocity would mean you are adding energy by creating it.
Your experience had nothing to do with the speed of sound vs temperature. You encountered the odd phenomenon called sound refraction where the sound waves are bent so you would not hear a “supersonic” crack at one temp but would at another as sound refraction can vary by temp and is especially “attenuating like” at high frequency impulse noise ranges like that of a bullet being fired. In other words, your “subsonic” sound was still traveling at supersonic velocity but it was refracted resulting in you simply not hearing it as much.
He was quoting the speed of sound at those temperatures, not the bullet’s velocity.
no, he was saying because of the speed of sound vs temp that the bullets velocity changed.
No dude 🤦♂️. Anner is exactly correct. The bullet didn’t change velocity, the speed of sound changed.
That’s the very clear point of that paragraph I wrote. The bullet was going like 1,110 FPS the entire time. When it was cold out, 1,110 FPS was faster than the 1,090 FPS speed of sound, which means the 1,110 FPS bullet was supersonic and had a sonic boom. When it was warm out, the exact same 1,110 FPS bullet was slower than the now 1,130 FPS speed of sound so the 1,110 FPS bullet was subsonic and made no sonic boom. The bullet’s velocity never changed.
he said it with..
“…the velocity straddles the speed of sound so closely that I’ve been out on the range shooting suppressed where every shot was supersonic in the morning in 30- to 40-degree temperatures (speed of sound ~1,090 FPS at 35 degrees) and every shot was subsonic in the afternoon in 60- to 70-ish-degree temperatures (speed of sound ~1,128 FPS at 70 degrees).”
he is specifically referring to the bullet velocity with “…the velocity straddles the speed of sound so closely …” and further specifically relates that “speed of sound” to temperature.
he was saying because of the speed of sound vs temp that the bullets velocity changed between subsonic and supersonic. He is claiming the laws of physics some way or another do not apply to his magical bullets that “straddles the speed of sound so closely…”
“straddles” is not what happened. Even if their velocity did somehow “straddle” “the speed of sound so closely…” you still can not speed up a bullet fired at subsonic velocity to supersonic.
“straddles the speed of sound so closely… is him trying to explain something he doesn’t understand- “oh look, I don’t hear the supersonic crack at this temp but do at that temp with the same bullets so it must be they straddle the speed of sound so closely that the temperature changing the speed of sound causes it”.
There is no such thing as a bullet that “straddles the speed of sound” that can switch from subsonic velocity to supersonic velocity or supersonic velocity to subsonic velocity, either its designed for subsonic velocity or its designed for supersonic velocity and can’t be both.
He also had magical bullets in another weekly missive where he claimed that bullets speed up in a suppressor beyond the muzzle velocity speed.
This is not the first time he has introduced “pseudo science” as the reason something happened. His articles are good, but he needs to stay away from the pseudo science.
Why are you replying to me and saying “he said,” “he is saying,” etc. It’s me. I wrote the article. I’m the author of it and I’m telling you what that paragraph means.
When I said the bullet “straddles the speed of sound” what I mean is that the bullet’s unchanging velocity is right in the range of the varying speed of sound. Like a typical 124 grain 9mm, which does about 1,120 FPS from a pistol. This is the speed of sound when the air is like 63 degrees. When the air is colder, that 1,120 FPS is supersonic. When the air is warmer, that 1,120 FPS is subsonic. The bullet’s velocity DOES change between subsonic and supersonic even though the velocity is exactly the same the entire time. This is because the speed of sound has changed. At 1,120 FPS the bullet is supersonic when it’s cold out and at the same 1,120 FPS the bullet is subsonic when it’s warm out. This is not hard to understand.
“He also had magical bullets in another weekly missive where he claimed that bullets speed up in a suppressor beyond the muzzle velocity speed.”
Yes, dude. Adding a silencer to the end of a barrel increases bullet velocity usually by 1% to 3% vs. the same gun without the silencer attached. You went way into the weeds on what you suspect the physics are but nobody cares about your random theories; just go chronograph it for yourself as dozens and dozens of people, including me, have (or google other peoples’ chronograph testing results of this very experiment, which are all over the dang interwebs). You’ll see with all sorts of guns and all sorts of ammo types that adding a silencer to the barrel increases the bullet’s velocity.
At this point I’m fairly convinced that there’s no way you’re actually this stupid and you’re just making absurd arguments to goad gullible fools like me into wasting time trying to show you reason. There’s no way your reading comprehension could be this poor. I just can’t believe it. No way can you read a paragraph explaining how the speed of sound changes with temperature and think that I’m talking about the bullet changing speed? No way. After I saw your first comment I thought maybe I needed to edit my article to make that parts clearer but, no, it’s perfectly clear that I’m saying the bullet is going one speed the whole time and the speed of sound is changing. You’re trolling. If not, seek help.
nit picked.
maybe he should have said the speed of sound straddles the velocity of the projectile at the temperatures mentioned.
Jeremy, 1,110 FPS is supersonic sound range.
No, Anner is not exactly correct.
Plus read carefully what you write now ….
“The bullet was going like 1,110 FPS the entire time. When it was cold out, 1,110 FPS was faster than the 1,090 FPS speed of sound, which means the 1,110 FPS bullet was supersonic and had a sonic boom. When it was warm out, the exact same 1,110 FPS bullet was slower than the now 1,130 FPS speed of sound so the 1,110 FPS bullet was subsonic and made no sonic boom. The bullet’s velocity never changed.”
1. You could not have “heard” a “sonic boom”. A “sonic boom” sound has a frequency range of 0.1–100 hertz that is considerably below that of gunfire. You did not hear a “sonic boom” from gun fire.
2. You can not relate the velocity of a bullet to the speed of sound as a relational comparison. Its two different things that do not share a common unit. Its a false comparison. The velocity of a bullet is determined by the energy that propels it – the speed of sound is how fast or slow sound travels in open air not if the sound makes a supersonic crack or not.
3. Now you say the bullet velocity did not change, but previously you said “…the velocity straddles the speed of sound so closely that I’ve been out on the range shooting suppressed where every shot was supersonic in the morning in 30- to 40-degree temperatures (speed of sound ~1,090 FPS at 35 degrees) and every shot was subsonic in the afternoon in 60- to 70-ish-degree temperatures (speed of sound ~1,128 FPS at 70 degrees).” – you directly related bullet velocity to “speed of sound” vs temp.
4. “…the speed of sound changed….” The speed of the sound energy its self does not change, the speed at which the sound energy travels through open air changes – its two different things. that’s what a “speed of sound” measurement/calculation is – its a measurement/calculation of how fast or slow a sound energy travels through open air – it does not determine what that sound energy sounds like. A sound energy wave that travels inherently at, for example for the sake of math, 10 m/s still has the inherent 10 m/s speed energy – but traveling through air the speed at which that 10 m/s speed energy is transmitted is slower or faster depending on variables – in other words “speed of sound” determines when you will hear the sound not if you will or will not hear the sound. The same sound is there all the time, if “The bullet was going like 1,110 FPS the entire time” it had a supersonic pressure sound wave in front of it the whole time.
I’m not sure if you are aware of this or not, it looks like you aren’t – but, for a bullet to make or not make a “supersonic” crack depends only on one thing and that is the velocity of the bullet. Yes, you did say the bullet changed velocity in what you wrote and still write now.
Your experience had nothing to do with the speed of sound vs temperature. You encountered the odd phenomenon called sound refraction where the sound waves are bent so you would not hear a “supersonic” crack at one temp but would at another as sound refraction can vary by temp and is especially “attenuating like” at high frequency impulse noise ranges like that of a bullet being fired. In other words, your “subsonic” sound was still traveling at supersonic velocity but it was refracted resulting in you simply not hearing it as much.
You’re wrong on everything. You’re starting with an incorrect premise: “1,110 FPS is supersonic sound range.” Sometimes that is supersonic. Sometimes it is subsonic. The speed of sound changes depending on air temperature. If you cannot understand this we cannot have a discussion. Please type below the speed of sound at 32* F and the speed of sound at 72* F and then we’ll talk further. Until you tell me the speed of sound at those temperatures I will not reply to you again.
@tsbhoa.p.jr — totally correct. That is how I should have phrased it and I am going to amend my language in the article now to make it clearer as per your suggestion there.
“Yes, dude. Adding a silencer to the end of a barrel increases bullet velocity usually by 1% to 3% vs. the same gun without the silencer attached.”
No it doesn’t. What you were seeing was the sudden peak release of energy left from after the bullet slowing down in the “silencer”.
You can demonstrate this your self with a rubber band. Place it on your finger and fire it across the room. Its held back from realizing its kinetic energy peak until you released it, but its energy can never be more than what it had to begin with. But maybe the simple observation effects witnessed with this little experiment would be too much for you in considering all the factors involved beyond a “duh! rubber band fun”, I’m not sure
“At this point I’m fairly convinced that there’s no way you’re actually this stupid and you’re just making absurd arguments to goad gullible fools like me into wasting time trying to show you reason.”
If you are gullible its because you see yourself as such. I’m not trying to goad anyone into anything.
I do physics for a living and have for many years, ever since I got my masters in physics. I’m not making “absurd arguments”.
I’m tired of seeing pseudo-science in articles being presented as if its a real thing trying to lend some sort of ‘authoritative” credibility, assuming the audience is stupid. I’m tired of seeing ignorant butchering of simple observational effects being attributed to mysterious “velocity straddles” type of thing while at the same time saying the very thing that was happening is suddenly not happening in “explanation” while basically saying it is happening in the same explanation yet the author is so tunnel visioned they can’t see it. I’m tired of seeing articles that use vague unsupported interpretations of observation that are easily explained.
I assure you that your “magic bullets” are not real, nor are your observational interpretations. But this is your article, feel free to make it as wrong as you’d like.
“You’re wrong on everything. You’re starting with an incorrect premise: “1,110 FPS is supersonic sound range.””
No, I’m not “starting with an incorrect premise” You left out part of what I said, this is it “1,110 FPS is supersonic sound range.”- see the word “range”? 1,110 FPS is supersonic and for sound on the lower edge of the range for a supersonic bullet, but it is still supersonic for a bullet.
“Sometimes that is supersonic. Sometimes it is subsonic. The speed of sound changes depending on air temperature. If you cannot understand this we cannot have a discussion. Please type below the speed of sound at 32* F and the speed of sound at 72* F and then we’ll talk further. Until you tell me the speed of sound at those temperatures I will not reply to you again.”
I never said “The speed of sound changes depending on air temperature.” it does, but it does not mean a bullet will be supersonic or subsonic just by you trying to string together two unrelated units to claim one affects the other in terms of velocity or sound.
Now you say of 1,110 FPS that “Sometimes that is supersonic. Sometimes it is subsonic” – after saying previously that the bullet was traveling at 1,110 FPS the whole time. If a bullet is traveling at 1,110 FPS that is in the supersonic range, period.
Once again “speed of sound” does not determine if a sound will be made or not. It is only the speed at which a sounds travels through open air, not if it exists or not. You basically started with the premise speed of sound determines if a sound existed or not by citing what you heard or not at different temps. You basically said it many times and even now in this missive of yours with this demand for a calculation and you don’t even realize it.
Is that it? You base your whole article on a calculation that seemed correct ’cause the words “speed of sound” without even realizing what “speed of sound” actually means?
If you cannot understand basic high school science then you don’t need to be discussing it.
“modern day ammunition “power charge””
should have been … modern day ammunition “powDer charge” …
ten paragraphs of wrong.
and still with the corrections.
say “der” again. and i will say bloviate.
This has all the ear marks of “Believe in the Science”. But who’s Science?
I once had an engineer who designed steel manufacturing plants explain to me why the home
hot water recirculation setup I was contemplating installing would not work.
Even though you can buy kits to do just that in Home Depot.
The author’s arguments sound the most compelling to this pragmatic reader. Even though I don’t have the sheep skin on the wall, I’ll go with the test results.
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