For those of you lucky enough to be able to browse TTAG at work and watch a YouTube video like the one above, I hope the audible difference between supersonic and subsonic ammo when shooting through a suppressor comes through. The only difference being, of course, the actual sonic boom of the bullet — the “CRACK” of it breaking the sound barrier on its flight downrange. It’s a lot louder than one might expect, and is actually much louder than I can capture on video, as. . .

the truth is microphones on cell phones and videos cameras max out between 90 and 110 dB. While my camera in this configuration won’t dampen or scale down audio after a volume spike, the sonic boom absolutely maxes it out. In a lot of calibers it’s actually uncomfortable to shoot supersonic ammo without ear protection, whereas a subsonic load with the same powder charge can be barely noisier than the sound of the action cycling.

In real life, the difference is even more pronounced than in the video.

As I have seen many comments on other videos and elsewhere online suggesting that the difference is actually due mostly to the higher power and pressure of supersonic loads:

  • In the video, the exact same ammo shot through the Remington 597 HB .22 LR rifle is fired through the Walther PPQ .22 pistol. While the sub/super difference is massive in the 597, both ammo brands stay subsonic in the short pistol barrel and the two are completely indistinguishable from each other.
  • It is true in many cases — for example .300 BLK and many .22 LR brands — that subsonic ammo and supersonic ammo are loaded to entirely different power specs. However, many calibers and brands of ammo achieve subsonic velocity by simply using a heavier projectile that doesn’t go as fast even with the same power and pressure behind it. This becomes extremely apparent when you take the exact same round and find that it’s supersonic in your 7.72″ bbl CZ Scorpion Evo and subsonic through a 4.5″ bbl pistol.
  • You can hear the sonic boom travel downrange. The echo and the crack follow the bullet. It’s a readily apparent difference vs. the sound coming from the gun.

Although the following video was just meant to be chronograph testing of the American Eagle “Suppressor” ammo, it’s queued up here to start at a similar subsonic/supersonic audio test:

45 Responses to The Variable Sounds of Silence: Subsonic vs. Supersonic Ammo

  1. Silencers – for the saftey of all.

    I propose we go after this in a different manner. Lets ask OSHA/EPA to go after making silencers madatory. So we don’t hurt our precious hearing, or that of neighboiring people nd prey.

    It worked with jet engines….

    • Please, let us not beg government to ban, or make mandatory, anything whatsoever, firearm related or not.

      • If It were not for the fact that this could be an example of perpetual motion and infinite (taxpayer) money spent, this could be an epic interdepartmental battle.

        You are right about more governmental regulations though….

  2. Unfortunately the answer is not really. It’s kind of there, but is nothing compared to hearing a suppressed super versus suppressed subsonic rounds.

    I’ve done this before, where I show videos of supressors, then take them to the range with my 9mm can with subs and supers. In the videos it seems like there is a difference, but it’s not much. Even suppressed most shots will max out the mic. On the range, there is really every good reason to shoot subs of it’s reasonable. With my electronic ear pro I can pick up the subs hitting the burm, but can’t do that with the supers.

    • I was able to tell the difference from the resulting echo in the woods. Subsonic rounds didn’t make an audible echo. Supersonic ones made a big echo… Like an unsuppressed gunshot kind of echo.

      • Originally I actually mentioned in the article that the echo is a better indicator of the noise difference than the shots, but explained it so clumsily that I just deleted it haha. Also, the fact the you can clearly and loudly hear the bullet impacts and ricochets on subsonic shots but that’s all totally drowned out on supersonic shots.

        • It’s a rare occurance when I am able to express myself clearly typing and It’s always on an iPhone so I generally lose my train of thought long before I can type a cogent statement. These things happen.
          I wasn’t able to hear the impact over the sonic boom either. But In theory the supersonic rounds would make more noise upon impact because of the higher velocity. So moral of the story is there a ton of loud aspects of the sport of shooting .

  3. Ya but assassins shouldn’t have such easy access to silencers. Debating whether or not to add a /sarc tag.

  4. I live in the San Francisco Bay Area. I have a 50`by 30` back yard and I shoot Aguila powderless .22 out of my Remington bolt rifle. Sounds like an air gun. Neighbors can’t see because of some trees so none have ever said anything. Love the ammo. Also please keep this just between us. thanks

    • someone just spilled their hummus and are trying to dig the iphone out of their genuine hemp fiber pants to call the cops. imagine, real guns in SF!!! OMG, the humanity!!

        • A lot of city laws banning discharge of firearms do include air guns and even bow and arrow though haha. So no gunpowder doesn’t always mean legal ;-). I used to shoot those “frog farts” constantly. Whatever the CCI primer only is called, and bricks of Aguila Colibri and Super Colibri. All sounds like dry firing out of a rifle and is still strong enough to be really accurate and reliably break bottles and such. But… I found out that it’s surprisingly loud out of an NAA mini revolver haha. Actually hurt my ears.

          Of course, since moving back to WA and getting a suppressor, I haven’t used those rounds since. May as well shoot real ammo if it’s just as quiet as primer-only. And it is (as long as it’s subsonic!).

        • Youtube comparisons between Colibra versus CCI Quiet ends up with CCI being MUCH more accurate with only marginal differences in noise.

        • My Colibri experience was limited to only a few boxes, and the CCI stuff was so long ago I don’t much remember accuracy. It was certainly quiet. I’ve gone through many bricks of Super Colibri though. It used to be available really dang cheap. That stuff was very accurate for me. We had a setup at the lake cabin that put cans and such out at 30-40 yards and it was rare not to hit specific portions of the cans and other targets with a 4x scope. It was plenty consistent and accurate. We even lobbed it out like 250 yards aiming at a target we had floated out onto a pond hahaha. The splash of the water let us figure out the hold and walk it in, but once we had the hold right it was hitting consistently.

    • Well, ‘wet my beak’ with some of that 22lr ammo, and your neighbors will never know…

      (Blackmail is such a harsh word. Extortion, not so much…) 😉

  5. Yes, definitely make a new law to make it illegal for registered assassins to buy or use these suppressors. Anything can be fixed with another new law. Just ask any lawyer or legislator. 😉

    • wait what? assassins have to register now? Man, nobody told me, this is bullshot! Do i get benefits and healthcare if I am registered?

  6. One of my favorite things about shooting .22 rifles is hearing that supersonic crack burn its way downrange behind the bullet. Someday I’d like to have a suppressor to separate the bang from the crack. That would be fun.

  7. Here is something from NSSF on OSHA safety guidelines for range employees. This is old, 1996, but perhaps useful for someone trying to persuade an ambitious staffer or legislator to sponsor a bill in their state to make silencers legal, or better, remove them from NFA.

    http://nssf.org/ranges/rangeresources/library/detail.cfm?filename=facility_mngmnt/design/using_risk_assesment.htm&CAT=Facility%20Management

    And here is something more recent citing study of overpressure effects on the inner ear and cochlea of animal subjects, modeled to understand what blast effects are long lasting in veterans of IED attacks.

    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3698122/

    There’s a new silencer manufacturer association…I’d guess they are working on lobbying, and would appreciate help from end-users to find proactive legislative solutions, ground up.

    Thats what worked for CCW movement, per “The Rise of the AntiMedia”.
    Here is a recent

      • The point being, the best defense is a good offense, and rather than be only reactive, on the abuse of the ATF, perhaps it would be helpful to educate the public and legislators on the reality in Europe, for example, that sound suppressors are widely considered responsible firearms use, as hearing conservation.

        I’m sure somewhere in the mists of time that Tommy guns were being banned, that silencers were considered a means of controlling the Mafia Assassin, or something…

        Educating the public on common-sense gun safety both deflects from the deliberate disinformation campaign that is obviously being coordinated, again, by this WH, and faux.orgs for the children, for the purpose of gun confiscation.

        • And points out to a newly awakened sleeping giant (the silent majority that is reflected in the Pew Research as majority and rising, who dont want more gun control laws) and the influence of their votes to obtain the biggest swing in political power from the left to rights, ie greatest number of congressional and governor seats going R in 130 years.

          The fast b1tchslap delivered to the ATF on 5.56 bans and shell shocked responce from Dems trying to figure out which among them to throw under the bus, says now is the time to press for change, at ATF, and one way is to strip from them bad gun laws at the federal level, piece by piece, while the memory of Executive Abuse of constitutional rights is added to Executive Abuse of agencies…

        • Apparently silencers were added to the NFA due to poaching that was happening during the great depression. Not poaching of wild animals, but of livestock. Lots of desperate people and such, and apparently ranchers pushed to see silencers added to these laws. Which would be understandable (the motivation for it). I really don’t know if this is historically accurate, but it’s certainly plausible. As far as I’ve been able to find in research, silencers are and were almost never used in crimes. Adding a $200 tax to these things — like $3,100 in 1934 dollars, ensured that only a certain class of people could afford these regulated items. Significant numbers of gun control regs since have also simply focused on making ownership expensive and, therefore, out of reach for poor folks, which often included minorities, etc.

        • Thank you, Jeremy. All the more reason to erase the law, for the sake of the childrens (hearing).

        • @-Jeremy S

          Back in the 70’s my grandfather told me the wild game in the northeast was severely impacted by the Great Depression. Folks who thought they could feed their hungry family with a rifle found game was very scarce.

          That was Franklin, Mass.

        • Makes sense, too. I guess, then, just “poaching” in general was prevalent. Hard to pin that on someone since walking around with a firearm wasn’t a crime. But if the poachers were using silencers, homemade or otherwise, to kill livestock at night or kill wild animals near where people live, now you pass a law that makes ownership without the $$$$ tax a massive felony and you’ve basically made a pre-crime constructive possession anti-poaching law.

          Of course, thanks to Hollywood everyone thinks that silencer = assassin and that violent crime would go up if only people could discharge firearms without startling the neighbors. Too bad it’s stupid easy to create a homemade silencer, plus there are plenty of legit ones out there, and there have been like two crimes committed with them ever. You know, other than the crime of having an unregistered one. And alleged poaching during the Great Depression.

    • One form of Progressive propaganda is the use of disinformation, in the form of change the subject…

      Good book on Amazon just out, that shows how Lenin and Stalin created the tools and techniques used by the Progressives today, in particular on this last ditch effort coordinated campaign for gun control, that…

      Oh, by the way, disracts the LIVs from the abject moral failure and utter hypocrisy of this WH, talking one thing for political legacy and doing another in the most underhanded and irresponsible abuse of power yet, advocating fundamental approval of intercontinental platformed nuclear arms to the one totalitarian state that has launched terrorist attacks against the US since 1979, and preaches the annihilation of a entire people, the complete destruction of a neighboring state, on a religious basis.

      • It really is, yeah, as all standard .45 ACP is subsonic. But the .45 ACP “suppressor” ammo that’s on the market from American Eagle and others does usually add a couple other features that you want when shooting suppressed, such as particularly clean-burning powder, lead-free primers, TMJ bullets, etc. All of those things being designed pretty specifically to keep your suppressor cleaner inside with less carbon and lead fouling, etc, which is something I can get behind.

  8. Any ballistics gurus want to chime in on what traversing the sonic barrier does to pistol bullets in flight? I was under the impression that is was bad to very bad hence why some people preferred handguns that normally are subsonic (like .45’s) for accuracy. I am thinking a heavier projectile moving more slowly cannot help either.

    Would love to hear a subsonic not suppressed verse a supersonic suppressed. Kind of hard to touch this though:

    • “Would love to hear a subsonic not suppressed verse a supersonic suppressed.”

      Subsonic not suppressed would be louder. Without the suppressor, I can’t tell the difference between subsonic ammo (that is, normal pressure ammo like the AmEag stuff, CCI Standard Velocity, etc) and supersonic ammo. The sound of the gunshot is so loud that the sonic boom really just can’t be heard over it. In the case of shooting suppressed, the sonic boom is really loud. In the case of shooting unsuppressed, the sonic boom isn’t really audible. So without a can, there is zero reason to buy and shoot subsonic ammo. Any difference in volume isn’t noticeable.

  9. Can you speak to the accuracy of subs vs supers? In my testing, I’ve found the (lone) subsonic ammo that I have has vastly out-performed the supersonic in terms of accuracy. I’ll be submitting a report to TTAG shortly, but the spoiler is that Aguila SE Subsonic .22lr has the most consistent and lowest groups in the ammo that I’ve tested across 3 different rifles.
    I envision the projectile becomes slightly unstable as it breaks the sound barrier, affecting accuracy. Thoughts?

  10. A chronograph cannot determine whether a bullet is subsonic.

    Relative to sound, there are three regions of velocity: subsonic, transonic, and supersonic. Subsonic means there is NO localized sonic or supersonic airflow, anywhere on the object. Transonic means there is _some_ localized supersonic flow but also _some_ subsonic flow. Supersonic means there is ONLY supersonic flow; NO localized subsonic anywhere on the object.

    So if you were to accelerate a jet (or load cartridges incrementally hotter) until reaching the speed of sound, before crossing the “sound barrier,” some of the air it was pushing aside would HAVE TO have been accelerated to the speed of sound, resulting in localized supersonic flow. The object itself is yet below the speed of sound, but some of the air surrounding it — in its haste to get out of the object’s path — has exceeded the speed of sound. And it makes a ‘sonic boom.’

    The velocity at which this first occurs is called the ‘critical Mach number.’ From that velocity and faster, until the object has shed the last remnants of its localized subsonic flow, it is neither subsonic nor supersonic, it is TRANsonic. And since it is the air — and not the bullet — that causes the supersonic crack, that crack already will have begun, despite the fact that the bullet has not yet reached the speed of sound.

    Point of fact, for any object that produces drag, the subsonic and supersonic regions never meet. NEVER. They ALWAYS are separated by the transonic velocities.

    Research done by Alan C. Paulson, widely regarded as the dean of suppressors (http://bit.ly/1cVvKBB), showed that a bullet traveling as little as 8/10ths of the speed of sound can have entered the transonic region and begun producing a supersonic crack. Exactly where it will begin varies according to bullet design but Paulson ballparks it at 0.8 Mach.

    For supporting evidence, look at the ballistic coefficient tables for any bullet, such as this one: http://i.imgur.com/LQ5RR29.png. Notice that up until about 0.8 Mach, the drag curve is more or less flat, then it suddenly rockets skyward. This is because the creation of the supersonic shockwave introduces a whole new form of drag, ‘wave form drag,’ that doesn’t exist when the bullet is entirely subsonic. In fact, it is the introduction of that ‘wave form drag’ that is responsible for the huge increase in the drag, which starts BEFORE the bullet reaches the speed of sound. Where the drag curve first starts to climb marks the critical Mach number. And the magnitude of the wave form drag increases as the local regions of supersonic flow spread over more of the bullet, peaking only once the bullet is entirely supersonic.

    So. Your chrono cannot tell you whether your bullets are subsonic. Sorry to disappoint, but that’s a fact of science. But fortunately, your ears can.

    A sonic shockwave is a very high energy region of air (due to energy it stole from the bullet, hence the steep drag curve), and will reflect off anything — and everything — it runs into. Which means that if your bullets are transonic OR supersonic, unless you’re somewhere where there’s nothing for miles around that the shock wave can bounce off of (like in the middle of the Bonneville Salt Flats), you WILL hear the echo. No echo, OTOH, means subsonic. As in BELOW transonic.

    Listening to your video, I don’t hear any echo from the ‘subsonic’ rounds. If the audio reproduction is true, that necessarily would mean that the bullets your chrono told you were subsonic were, in fact, subsonic, but it wasn’t your chrono that told me that. It was my ears.

  11. Phil LA, if you’ll check the advertised velocities on match-grade .22LR ammo, you’ll see they’re all subsonic.

    All bullets tend to experience some loss of stability when they slow through the transonic region, so bullets tend to fly truer if they altogether avoid the transition. In the case of elliptical and round-nosed rimfire projectiles, this is primarily due to the fact that, in the transonic region, only parts of the bullet are experiencing supersonic flow, which also necessarily means only parts of the bullet are experiencing the tremendously strong wave form drag. The uneven distribution of this drag is what unsettles the bullet’s composure.

    Those same elliptical and round-nosed bullets lack the aerodynamic efficiency to fight against the ravages of wave form drag for very long, and it soon pulls them back into the transonic region. Which means that avoiding the transonic problem by driving them fast enough to remain above the transonic region until they reach the target isn’t practical, except at very short ranges. What is practical is to fire them at velocities already below the critical Mach number. Then the transonic problem never manifests itself.

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