Silencer Physics Question

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94collin
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Silencer Physics Question

Post by 94collin »

Why does a 22 lr subsonic round go supersonic when shot at a body of water? If somebody could provide me a quick detailed answer behind the concept, I'd be more than happy! :D

Thanks
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Re: Silencer Physics Question

Post by Bendersquint »

94collin wrote:Why does a 22 lr subsonic round go supersonic when shot at a body of water? If somebody could provide me a quick detailed answer behind the concept, I'd be more than happy! :D

Thanks
Thats a new one, never heard that before.
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Emilio
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Re: Silencer Physics Question

Post by Emilio »

Was it Remington ammo? :mrgreen:
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Re: Silencer Physics Question

Post by Will_M »

It doesn't.
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Re: Silencer Physics Question

Post by Armorer-at-Law »

Image
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Re: Silencer Physics Question

Post by Historian »

94collin wrote:Why does a 22 lr subsonic round go supersonic when shot at a body of water? If somebody could provide me a quick detailed answer behind the concept, I'd be more than happy! :D

Thanks

Wow!

Please send us the reference to the article in the Phys. Rev. on this violation of the 2nd law of
thermo dynamics.

Best WAG if true that I can come up with is that there is a Black Hole at the center of
the body of water and that its event horizon is accelerating the .22 like hell.

Never heard nor run across this supposed phenomenon in the over half a century of shooting.
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HKschalldampfer
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Re: Silencer Physics Question

Post by HKschalldampfer »

94collin wrote:Why does a 22 lr subsonic round go supersonic when shot at a body of water? If somebody could provide me a quick detailed answer behind the concept, I'd be more than happy! :D

Thanks
Are you referring to the sound of the projectile impacting water? If you're asking about the noise upon impact it's not accelerating and breaking the sound barrier, it's just slamming into an object that happens to reflect/amplify noise really well.
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Re: Silencer Physics Question

Post by rimshaker »

94collin wrote:Why does a 22 lr subsonic round go supersonic when shot at a body of water? If somebody could provide me a quick detailed answer behind the concept, I'd be more than happy! :D
Bullets tend to skip or ricochet across the water. You're probably referring to the ricochet sounds.

I've seen 9mm subsonic skip up to 7-8 times in a row.... better than skipping stones!
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Re: Silencer Physics Question

Post by Dr.K »

Historian wrote:
94collin wrote:Why does a 22 lr subsonic round go supersonic when shot at a body of water? If somebody could provide me a quick detailed answer behind the concept, I'd be more than happy! :D

Thanks

Best WAG if true that I can come up with is that there is a Black Hole at the center of
the body of water and that its event horizon is accelerating the .22 like hell.
Seems that the said anomaly would indeed suck the bullet in at an ever increasing velocity, but also would suck the sound into it also....possibly the shooter. Might be a concept someone could explore...Creating a mini-blackhole inside a silencer that sucks in the sound, but not the projectile :lol:
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Re: Silencer Physics Question

Post by SUB-MG »

rimshaker wrote:
94collin wrote:Why does a 22 lr subsonic round go supersonic when shot at a body of water? If somebody could provide me a quick detailed answer behind the concept, I'd be more than happy! :D
Bullets tend to skip or ricochet across the water. You're probably referring to the ricochet sounds.

I've seen 9mm subsonic skip up to 7-8 times in a row.... better than skipping stones!
THis is my vote. The bullet richochet off the water and made a similar sound to when your bullet ricochet off of a rock or other object.
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Re: Silencer Physics Question

Post by Gik-Tal »

It doesn't it has to do with the way sound moves, in the air the speed of sound is 1125 Ft/Sec. in water the speed is 5000 ft./sec. so sound waves moving from air thru water speed up by around a factor of 4. The bullet does not go any faster, just the sound waves that surround it do.
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Re: Silencer Physics Question

Post by doubloon »

Finally an answer worthy of the question.
http://www.youtube.com/watch?v=BDtd2jNIwAU MUSAFAR!
http://www.youtube.com/watch?v=8CrOL-ydFMI This is Water DavidW
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continuity
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Re: Silencer Physics Question

Post by continuity »

Gik-Tal wrote:It doesn't it has to do with the way sound moves, in the air the speed of sound is 1125 Ft/Sec. in water the speed is 5000 ft./sec. so sound waves moving from air thru water speed up by around a factor of 4. The bullet does not go any faster, just the sound waves that surround it do.
As cooly technical as this answer is, I'm not sure I follow. (Who am I trying to kid... I looked at this for a while and can't quite make the mental connection)

Is it that at the instant the projectile enters the water, the velocity of the sound wave is increased in the water near the surface, and transfered to the air, at a now increased velocity?
What amount of a man is composed of his own collection of experiences... and the conclusions that those experiences have allowed him to "know" for certain as "Truth"? :Ick
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Re: Silencer Physics Question

Post by TROOPER »

continuity wrote:
Gik-Tal wrote:It doesn't it has to do with the way sound moves, in the air the speed of sound is 1125 Ft/Sec. in water the speed is 5000 ft./sec. so sound waves moving from air thru water speed up by around a factor of 4. The bullet does not go any faster, just the sound waves that surround it do.
As cooly technical as this answer is, I'm not sure I follow. (Who am I trying to kid... I looked at this for a while and can't quite make the mental connection)

Is it that at the instant the projectile enters the water, the velocity of the sound wave is increased in the water near the surface, and transfered to the air, at a now increased velocity?
Hang on... I got this.

Here is the original question: Why does a 22 lr subsonic round go supersonic when shot at a body of water?
Here is the answer: It doesn't.

Sorry to get all technical

No external stimulus is acting to increase the velocity of the bullet once it is clear of the muzzle. It doesn't pick up velocity.

Perhaps the OP should place his chronograph under the water and use it to confirm this hypothesis. Otherwise, he's basing his musings on the sound alone - in which case the question is, "Why does a 22 lr subsonic SOUND as though it goes supersonic when shot at a body of water?" That is a different question entirely.

Speculation includes: ricochet makes the distinct sizzling sound associated with supersonic flight.
Speculation includes: fresh water, especially in a small, isolate body, makes a great reflector for sound, and an ordinary supersonic shot might suddenly seem louder as a result.
Speculation includes: impact of bullet in water makes a sound similar to that of a supersonic shot.
Speculation includes: differences in humidity and temperature directly over a body of water might provide just enough difference to lower the threshold for the speed of sound to make a marginally subsonic round supersonic.

One of the biggest problems here is that not only is the question poorly worded with a very bold assumption built into it, but it's also very unclear: shot NEAR water? Shot AT water? Shot INTO water? Shot OVER water? Prepositions matter. Are you shooting over a pond? Are you shooting INTO a pond? Why do you believe it's supersonic at all?

There's only one guarantee here: Your shot isn't picking up speed once it leaves the muzzle.
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Re: Silencer Physics Question

Post by doubloon »

continuity wrote:... can't quite make the mental connection)
...
Just between you and me, there isn't one. Shhhh.
http://www.youtube.com/watch?v=BDtd2jNIwAU MUSAFAR!
http://www.youtube.com/watch?v=8CrOL-ydFMI This is Water DavidW
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Re: Silencer Physics Question

Post by Historian »

Dr.K wrote:
Historian wrote:
94collin wrote:Why does a 22 lr subsonic round go supersonic when shot at a body of water? If somebody could provide me a quick detailed answer behind the concept, I'd be more than happy! :D

Thanks

Best WAG if true that I can come up with is that there is a Black Hole at the center of
the body of water and that its event horizon is accelerating the .22 like hell.
Seems that the said anomaly would indeed suck the bullet in at an ever increasing velocity, but also would suck the sound into it also....possibly the shooter. Might be a concept someone could explore...Creating a mini-blackhole inside a silencer that sucks in the sound, but not the projectile :lol:
This brings up the thorny issue, would then some overly zealous GS-7 at ATF declare Black Holes registered silencer parts and each
would require a stamp? Would you need get Stephen Hawking to sign your form prior to submission? And imagine trying
to measure the Db. Now that would literally suck ... including the meter.

:) :) :)
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Re: Silencer Physics Question

Post by 94collin »

Thank you to everyone, and your interesting replies including black holes and what not, haha. I am basing my question entirely on the sound that I hear. If anyone would be interested, I can possibly get ahold of a video to compare the sounds, and post a link?
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Re: Silencer Physics Question

Post by doubloon »

What you are hearing is either an echo or a ricochet.

If the bullet is not supersonic when it leaves the barrel then is sure as hell isn't supersonic later.
http://www.youtube.com/watch?v=BDtd2jNIwAU MUSAFAR!
http://www.youtube.com/watch?v=8CrOL-ydFMI This is Water DavidW
Complete Form 1s http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895
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Re: Silencer Physics Question

Post by Joker31D »

Top Ten Reasons a subsonic bullet goes supersonic over water

10. Ricochets off of a Kardashians' ass
9. Black Hole makes sudden appearance making it accelerate (Insert tech BS Here)
8. Because Jay Leno said so
7. Because it trying to beat David Letterman to the door.
6. It has a dinner date with the Kennedy Magic Bullet, and expects to get LUCKY!!!
5. Ammo makers are resorting to using pixie magic to keep up with the rimfire demand!!!!
4. Its running away from a SCARY Black Rifle
3. Global Warming!!!
2. Its a BS seeking bullet and you shot it near this thread

And the number 1 reason 22 subsonic bullets accelerate to supersonic speed over water is:

1. Its being plucked out of the air by gunshop owners trying to resell it on Gunbroker for a quick buck!!!!
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Re: Silencer Physics Question

Post by Fulmen »

That's just to darn funny :mrgreen: :mrgreen: :mrgreen:
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Re: Silencer Physics Question

Post by este »

Joker31D wrote:...


Maybe try the Random Chat section?
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continuity
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Re: Silencer Physics Question

Post by continuity »

doubloon wrote:
continuity wrote:... can't quite make the mental connection)
...
Just between you and me, there isn't one. Shhhh.
And now, in a non/less alcohol enhanced state, things become clearer.

1) doubloons common sense.
2) TROOP's ability to grasp what the F is really happening.
3) Law of Conservation of Energy makes #1 and #2, intuitively obvious to the casual observer...
What amount of a man is composed of his own collection of experiences... and the conclusions that those experiences have allowed him to "know" for certain as "Truth"? :Ick
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Re: Silencer Physics Question

Post by Capt. Link. »

Will_M got it right first.+1
My question is are you using a suppressor.Free-bore boost may raise the projectile into the transonic to supersonic range of speed.I would like to see manufacturers lower the velocity to no more than 1,000fps this will make the ammo quieter and more accurate by not being so close to the sonic edge and its buffeting.I think the question should be are you really subsonic when shooting factory ammo.I bet the bullet is not and the op can hear it passing over water.CL
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Re: Silencer Physics Question

Post by whiterussian1974 »

If no Free-boost from can, maybe you are just hearing the sound reflected off of the multiple wave surfaces that a body of water experiences from wind. The multiple reflection surfaces would act to amplify the reflected sound off multiple surfaces and cumulatively increase acoustic amplitude.

Just a thought. Maybe I am misinterpreting the effects.
PS: I like Armorer-at-Law's interpretation. I often felt this way in College Ha-ha. :P
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Re: Silencer Physics Question

Post by Ws7z »

This only works if the shooter is on a treadmill when the gun is fired.
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