A truly silenced 9mm - what would it take?

Skans · December 1, 2014, 05:43 PM

What would it take to get the decibels on a subsonic 9mm down to around 30-40? how large/long would the expansion chamber have to be?

BillM · December 1, 2014, 05:54 PM

Quiet rural area
30 One-sixteenth as loud as 70 dB. Very Quiet

Library, bird calls (44 dB); lowest limit of urban ambient sound
40 One-eighth as loud as 70 dB.

30 to 40 is REALLY quiet. I suspect the firing pin falling might exceed it.

Gonna take one heck of a can to quiet a 9 that far.

My Liberty Kodiak TL can on a Savage FV-SR with Aquilla Sub sonics
sounnd like a gnat fart--and it's more than 40 dB.

Vt.birdhunter · December 1, 2014, 05:54 PM

Even dry firing can be louder than that; so is the sound of the slug hitting anything but air.

Theohazard · December 1, 2014, 06:16 PM

This looks very similar to the thread you started earlier this year:

http://thefiringline.com/forums/showthread.php?t=545737

Is there something left unanswered from that thread? I'm not being critical, just curious.

Machineguntony · December 1, 2014, 08:22 PM

I wonder what it would sound like if you shot a 9mm through a silencer for a 50cal. What if you used a hammerless single shot gun, so that there is no hammer drop sound and no cycling sound? Gotta be subsonic with no hard backstop, or else you will have additional sounds.

Someone should do the experiment and post a video with a decibel meter.

I wonder what the decibel reading would be.

Willie Lowman · December 1, 2014, 09:27 PM

I've shot an Uzi with an old AWC MK9 mounted on it. With 147 grain ammo all I could hear was the bolt chattering back and fourth.

But 30 decibels? I don't think so.

**JohnKSa** · December 2, 2014, 01:21 AM

Quote:

30 One-sixteenth as loud as 70 dB.

A reduction of 40dB in noise power is a reduction by a factor of 10,000 in the noise power.

Quote:

40 One-eighth as loud as 70 dB.

A reduction of 30dB would be a reduction by a factor of 1,000.

Decibels can be calculated by multiplying the log base 10 of the ratio of the two power levels by 10.

So if the ratio between the two power levels is 1000, we could represent that change in power in dB by calculating 10 x log₁₀1000 = 10 x 3 = 30

Mobuck · December 2, 2014, 07:18 AM

A "really silent" 9mm will have a lock to prevent the slide cycling.
With Remington C-Bee ammo, I can hold the slide of my Ruger 22/45 closed with my thumb so it doesn't make noise.

Skans · December 2, 2014, 08:42 AM

When I asked the question previously, I wanted to know, more from a practical standpoint, how quiet you can expect to make a 9mm.

In this inquiry, I'm more interested in knowing whether anyone has ever tried to make a super-sized silencer. Basically, how much increase in weight and size of the silencer would equate to a large reduction in decibels.

It's possible to nearly silence the exhaust noise from an internal combustion engine using large mufflers. At some point, I would think it would be possible to get the blast noise of a gun nearly silent. Has this ever been tried?

tirod · December 2, 2014, 11:27 AM

It's being tried all the time, the difficult part is that the gun produces gas pressure up to 55,000 pounds and it's difficult to control what's left when it escapes. An internal combustion engine is far far less, and the multiple cylinders allow having the pulses counteract each other.

But - a car is far from completely silent. Listen to a car rolling down hill and you will hear treads slapping on the road, the driveshaft working, and brakes making noise as they are applied. Much less automatic cooling fans under the hood, etc.

Same with a firearm. You could get the report controlled to a point, but what would be left is exactly what you hear charging the first round. All the clank clank and banging the action always has would become the next loudest thing.

"Silencers" don't, they just muffle the report. The best silenced guns have a closed locked bolt manually cycled to keep the noise down. With all the work around to get one that silent, it then becomes a matter of what might be a better method, knife, poison, or garrote. Some prefer a simple push as the subway tram enters the station.

Aside from that, electric cars come close to being silent, which is why they are required to play engine noise from a speaker so the blind won't step out into a crosswalk as they pass.

That same thinking might be behind the anti suppressor laws, we need to know exactly when and where somebody is shooting!

Willie Lowman · December 2, 2014, 11:34 AM

Major Malfunction did a test a while ago where he measured the db of guns being dry fired. He measured this from the shooter's ear. The average for a Remington 504 was 115 db and a 700 was 121 db.

So if a .22 striker is producing 115 decibels, I don't think you are going to get a 9mm that is quieter than that. And this takes me back to what I was saying about the MK9 and all I could hear was action noise...

JD0x0 · December 2, 2014, 02:08 PM

Not a 9mm but some good info..

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

Got a nagant revolver from 154db down to 123.72db (average) with a .45 cal suppressor (on a .310 cal barrel)

Vt.birdhunter · December 2, 2014, 02:32 PM

Quote:

115 db and a 700 was 121 db.

Those numbers are off by A LOT!

120 decibles is like fireworks, very load machinery, etc.

Dry firing is around 70 db, maybe 80 db

http://www.noisehelp.com/noise-level-chart.html

JD0x0 · December 2, 2014, 04:05 PM

When I dry fire my Ruger M77 Mk2, it makes my ears ring, so it's pretty loud, IMO. I'm looking for my decibel meter, now. I will report back ASAP.

Vt.birdhunter · December 2, 2014, 07:02 PM

SW revolver dry-fired just gave me around 85db at the shooters ear, 90 next to the hammer.

Glock 17 dry-fired was 83db measured at the ear. Cocking slide was 94db

Deja vu · December 3, 2014, 06:35 AM

I doubt you could ever make any firearm truly silent. That said the SilencerCo Wizard Staff looks promising .

Sorry but I have to add this spoof every time I see a post about a truly silent silencer.

9mm · December 6, 2014, 12:49 AM

Maybe on a rifle, that was chambered in 9mm like the MP5 built in surpressed.

A 16 inch barrel, with 12-14 inchs surpressed rifling, like a bullup style gun, but with a bolt action.

Maybe?
No clue, none of have been made.

JD0x0 · December 6, 2014, 01:23 AM

Technically a 9mm

sounds like a paintball gun.
https://www.youtube.com/watch?v=Af96XDdjvxY

Mobuck · December 6, 2014, 07:17 AM

When I dry fire my Ruger M77 Mk2, it makes my ears ring,

Well, my ears ring all the time and I can barely hear ANYTHING dry fire.

Willie Lowman · December 6, 2014, 09:44 AM

Quote:

No clue, none of have been made.

No, I don't think anyone has made a bullpup, bolt action, MP5SD with a 16" barrel.

However there are clones of the Delisle Carbine (normally .45 ACP) that have a report that is around 85 decibels. People have done some good work with the Spanish Destroyer carbines to make suppressed 9mm bolt actions. Also the Ruger 44/77 SD is worth mentioning.

If I was on a quest to make a super quiet 9mm I would use a T/C Contender with a 14" barrel. Integrally suppress it with the baffle stack extending past the muzzle 6" or so. I'm guessing that amount of internal volume would allow for a near "silent" 9mm. But I'm just guessing.

Skans · December 6, 2014, 01:30 PM

Quote:

Technically a 9mm sounds like a paintball gun.

That 9mm is more like a 7.62x39. Just think what it would sound like with a subsonic 9mm Luger.

December 1, 2014, 05:43 PM	#1
Skans Senior Member Join Date: November 20, 2008 Posts: 11,132	A truly silenced 9mm - what would it take? What would it take to get the decibels on a subsonic 9mm down to around 30-40? how large/long would the expansion chamber have to be?

December 1, 2014, 05:54 PM	#3
Vt.birdhunter Senior Member Join Date: March 18, 2009 Posts: 637	Even dry firing can be louder than that; so is the sound of the slug hitting anything but air. __________________ Maintaining a constant state of cat-like readiness and a heightened state of suspicious alertness.

December 1, 2014, 06:16 PM	#4
Theohazard Senior Member Join Date: April 19, 2012 Location: Western PA Posts: 3,829	This looks very similar to the thread you started earlier this year: http://thefiringline.com/forums/showthread.php?t=545737 Is there something left unanswered from that thread? I'm not being critical, just curious. __________________ 0331: "Accuracy by volume."

December 1, 2014, 08:22 PM	#5
Machineguntony Senior Member Join Date: June 22, 2013 Posts: 1,277	I wonder what it would sound like if you shot a 9mm through a silencer for a 50cal. What if you used a hammerless single shot gun, so that there is no hammer drop sound and no cycling sound? Gotta be subsonic with no hard backstop, or else you will have additional sounds. Someone should do the experiment and post a video with a decibel meter. I wonder what the decibel reading would be. __________________ Sent from Motorola DynaTac 8000x

December 1, 2014, 09:27 PM	#6
Willie Lowman Senior Member Join Date: March 5, 2009 Location: Uh-Hi-O Posts: 3,006	I've shot an Uzi with an old AWC MK9 mounted on it. With 147 grain ammo all I could hear was the bolt chattering back and fourth. But 30 decibels? I don't think so. __________________ "9mm has a very long history of being a pointy little bullet moving quickly" --Sevens

December 1, 2014, 05:54 PM	#2
BillM Senior Member Join Date: January 20, 2009 Location: Amity Oregon Posts: 791	Quiet rural area 30 One-sixteenth as loud as 70 dB. Very Quiet Library, bird calls (44 dB); lowest limit of urban ambient sound 40 One-eighth as loud as 70 dB. 30 to 40 is REALLY quiet. I suspect the firing pin falling might exceed it. Gonna take one heck of a can to quiet a 9 that far. My Liberty Kodiak TL can on a Savage FV-SR with Aquilla Sub sonics sounnd like a gnat fart--and it's more than 40 dB.

December 2, 2014, 07:18 AM	#8
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	A "really silent" 9mm will have a lock to prevent the slide cycling. With Remington C-Bee ammo, I can hold the slide of my Ruger 22/45 closed with my thumb so it doesn't make noise.

December 2, 2014, 08:42 AM	#9
Skans Senior Member Join Date: November 20, 2008 Posts: 11,132	When I asked the question previously, I wanted to know, more from a practical standpoint, how quiet you can expect to make a 9mm. In this inquiry, I'm more interested in knowing whether anyone has ever tried to make a super-sized silencer. Basically, how much increase in weight and size of the silencer would equate to a large reduction in decibels. It's possible to nearly silence the exhaust noise from an internal combustion engine using large mufflers. At some point, I would think it would be possible to get the blast noise of a gun nearly silent. Has this ever been tried?

December 2, 2014, 11:27 AM	#10
tirod Junior member Join Date: January 21, 2009 Posts: 1,672	It's being tried all the time, the difficult part is that the gun produces gas pressure up to 55,000 pounds and it's difficult to control what's left when it escapes. An internal combustion engine is far far less, and the multiple cylinders allow having the pulses counteract each other. But - a car is far from completely silent. Listen to a car rolling down hill and you will hear treads slapping on the road, the driveshaft working, and brakes making noise as they are applied. Much less automatic cooling fans under the hood, etc. Same with a firearm. You could get the report controlled to a point, but what would be left is exactly what you hear charging the first round. All the clank clank and banging the action always has would become the next loudest thing. "Silencers" don't, they just muffle the report. The best silenced guns have a closed locked bolt manually cycled to keep the noise down. With all the work around to get one that silent, it then becomes a matter of what might be a better method, knife, poison, or garrote. Some prefer a simple push as the subway tram enters the station. Aside from that, electric cars come close to being silent, which is why they are required to play engine noise from a speaker so the blind won't step out into a crosswalk as they pass. That same thinking might be behind the anti suppressor laws, we need to know exactly when and where somebody is shooting!

December 2, 2014, 11:34 AM	#11
Willie Lowman Senior Member Join Date: March 5, 2009 Location: Uh-Hi-O Posts: 3,006	Major Malfunction did a test a while ago where he measured the db of guns being dry fired. He measured this from the shooter's ear. The average for a Remington 504 was 115 db and a 700 was 121 db. So if a .22 striker is producing 115 decibels, I don't think you are going to get a 9mm that is quieter than that. And this takes me back to what I was saying about the MK9 and all I could hear was action noise... __________________ "9mm has a very long history of being a pointy little bullet moving quickly" --Sevens Last edited by Willie Lowman; December 2, 2014 at 11:45 AM. Reason: correction

December 2, 2014, 02:08 PM	#12
JD0x0 Senior Member Join Date: January 30, 2013 Posts: 1,037	Not a 9mm but some good info.. https://www.youtube.com/watch?v=GStcHyGQwcQ Got a nagant revolver from 154db down to 123.72db (average) with a .45 cal suppressor (on a .310 cal barrel)

December 2, 2014, 04:05 PM	#14
JD0x0 Senior Member Join Date: January 30, 2013 Posts: 1,037	When I dry fire my Ruger M77 Mk2, it makes my ears ring, so it's pretty loud, IMO. I'm looking for my decibel meter, now. I will report back ASAP.

December 2, 2014, 07:02 PM	#15
Vt.birdhunter Senior Member Join Date: March 18, 2009 Posts: 637	SW revolver dry-fired just gave me around 85db at the shooters ear, 90 next to the hammer. Glock 17 dry-fired was 83db measured at the ear. Cocking slide was 94db __________________ Maintaining a constant state of cat-like readiness and a heightened state of suspicious alertness.

December 3, 2014, 06:35 AM	#16
Deja vu Senior Member Join Date: March 14, 2010 Location: Border of Idaho & Montana Posts: 2,584	I doubt you could ever make any firearm truly silent. That said the SilencerCo Wizard Staff looks promising . Sorry but I have to add this spoof every time I see a post about a truly silent silencer. __________________ Shot placement is everything! I would rather take a round of 50BMG to the foot than a 22short to the base of the skull. all 26 of my guns are 45/70 govt, 357 mag, 22 or 12 ga... I believe in keeping it simple. Wish my wife did as well...

December 6, 2014, 12:49 AM	#17
9mm Senior Member Join Date: January 9, 2011 Location: Land of the Free Posts: 2,834	Maybe on a rifle, that was chambered in 9mm like the MP5 built in surpressed. A 16 inch barrel, with 12-14 inchs surpressed rifling, like a bullup style gun, but with a bolt action. Maybe? No clue, none of have been made.

December 6, 2014, 01:23 AM	#18
JD0x0 Senior Member Join Date: January 30, 2013 Posts: 1,037	Technically a 9mm sounds like a paintball gun. https://www.youtube.com/watch?v=Af96XDdjvxY

December 6, 2014, 07:17 AM	#19
Mobuck Junior member Join Date: February 2, 2010 Posts: 6,846	When I dry fire my Ruger M77 Mk2, it makes my ears ring, Well, my ears ring all the time and I can barely hear ANYTHING dry fire.