Why don't military sniper rifles have silencers?
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Zak Smith
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FWIW, the difference between suppressed and non-suppressed on all my bolt rifles is less than the MV S.D. of the load.
With regard to POI shift. I have used and seen demonstrated a wide variety of suppressor weights and barrel profiles. On some of my bolt rifles, there is "no" POI shift. On some, there can be a couple MOA of difference. The pattern is that the lighter the can and the stiffer the barrel, the less shift there will be.
On my 24" AI-AWP with a 20 oz can, there is "no" change vs. the AI-AW muzzle brake.
On my 26" .260 (med Palma contour), there is 0.2 mil difference.
With regard to POI shift. I have used and seen demonstrated a wide variety of suppressor weights and barrel profiles. On some of my bolt rifles, there is "no" POI shift. On some, there can be a couple MOA of difference. The pattern is that the lighter the can and the stiffer the barrel, the less shift there will be.
On my 24" AI-AWP with a 20 oz can, there is "no" change vs. the AI-AW muzzle brake.
On my 26" .260 (med Palma contour), there is 0.2 mil difference.
Alchymist
Member
Quote "3 decibels equals 2 times change, 10 decibels 100 times, 20 decibels 100 times, ect.
Ranb"
Close, 3 dB is 2X change, an increase in sound level by 3 dB will sound twice as loud, and a 3 dB decrease half as loud. But 10 dB however is not 100 times as loud, but just over 8 times . (3 DB = 2X, + 3 dB = 4X, +3 dB = 8 times, or 9 dB, 12 dB would then be 16 times louder). Hearing loss begins at about 80-85 dB. The dB scale is based on the response of the human ear to sound intensity, it is not linear.
Ranb"
Close, 3 dB is 2X change, an increase in sound level by 3 dB will sound twice as loud, and a 3 dB decrease half as loud. But 10 dB however is not 100 times as loud, but just over 8 times . (3 DB = 2X, + 3 dB = 4X, +3 dB = 8 times, or 9 dB, 12 dB would then be 16 times louder). Hearing loss begins at about 80-85 dB. The dB scale is based on the response of the human ear to sound intensity, it is not linear.
Hearing loss at 85 dB? I thought OSHA declares hearing loss at levels at or above 138 dB? *confused*
Ok Ok... it is not necessarily the dB that makes the gunshot destroy hearing. It is the sound pressure. I am not going to pretend to be an engineer so someone will have to chime in on perceived noise and how it relates to pressure. But the reality is that a suppressor does not reduce the noise so much as it reduces the sound pressure which is really what causes hearing damage.
http://www.engineeringtoolbox.com/sound-pressure-d_711.html
http://www.newton.dep.anl.gov/askasci/eng99/eng99325.htm
http://www.lhh.org/noise/archives/22-1/noisytoy.html
But here are some interesting dB ratings
Some Examples of Noisy Toys
-Certain rattles and squeaky toys are measured at sound levels as high as 110 dBA.
-Musical toys, such as electric guitars, drums and horns, emit sounds as loud as 120 dBA.
-Toy phones for small children are measured between 123 and 129 dBA.
-Toys that are designed to amplify the voice are measured at up to 135 dBA.
-Toys producing firearm sounds emit volumes as loud as 150 dBA one foot away from the noise source.
-Noise levels at video arcades can be as high as 110 dBA.
-Firecrackers create sound levels ranging from 125-155 dBA at an average distance of 10 feet and pose a serious hazard to hearing.
-Noise emitted from cap guns can be measured in excess of 140 dBA.
****
Makes the Trident-9 shooting 147gr 9mm at 122 dB look awesome.
Ok Ok... it is not necessarily the dB that makes the gunshot destroy hearing. It is the sound pressure. I am not going to pretend to be an engineer so someone will have to chime in on perceived noise and how it relates to pressure. But the reality is that a suppressor does not reduce the noise so much as it reduces the sound pressure which is really what causes hearing damage.
http://www.engineeringtoolbox.com/sound-pressure-d_711.html
http://www.newton.dep.anl.gov/askasci/eng99/eng99325.htm
http://www.lhh.org/noise/archives/22-1/noisytoy.html
But here are some interesting dB ratings
Some Examples of Noisy Toys
-Certain rattles and squeaky toys are measured at sound levels as high as 110 dBA.
-Musical toys, such as electric guitars, drums and horns, emit sounds as loud as 120 dBA.
-Toy phones for small children are measured between 123 and 129 dBA.
-Toys that are designed to amplify the voice are measured at up to 135 dBA.
-Toys producing firearm sounds emit volumes as loud as 150 dBA one foot away from the noise source.
-Noise levels at video arcades can be as high as 110 dBA.
-Firecrackers create sound levels ranging from 125-155 dBA at an average distance of 10 feet and pose a serious hazard to hearing.
-Noise emitted from cap guns can be measured in excess of 140 dBA.
****
Makes the Trident-9 shooting 147gr 9mm at 122 dB look awesome.
Alchymist
Member
I stated that hearing loss begins at 80-85 dB.
From your own link:
"How Loud Is Too Loud?
To know if a sound is loud enough to cause damage to your ears, it is important to know both the level of intensity (measured in decibels, dBA) and the length of exposure to the sound. In general, the louder the sound, the less time required before hearing will be affected. Standards set by OSHA (Occupational Safety and Health Administration) indicate that continued exposure to noise over 85 dBA will eventually harm your hearing. To avoid noise-induced hearing loss, OSHA recommends that hearing protection be worn in the workplace when loudness levels and exposure time exceed the allowable standards. "
(Emphasis added).
From your own link:
"How Loud Is Too Loud?
To know if a sound is loud enough to cause damage to your ears, it is important to know both the level of intensity (measured in decibels, dBA) and the length of exposure to the sound. In general, the louder the sound, the less time required before hearing will be affected. Standards set by OSHA (Occupational Safety and Health Administration) indicate that continued exposure to noise over 85 dBA will eventually harm your hearing. To avoid noise-induced hearing loss, OSHA recommends that hearing protection be worn in the workplace when loudness levels and exposure time exceed the allowable standards. "
(Emphasis added).
Zak Smith
Member
[ETA- I had a hard time figuring out your intent in that.. sentence? In any case, I think your math is correct but hard to understand in that form. Here it is layed out]
dB = 10* log (I/H)
(log base 10).
I/H is also known as the sound intensity factor (I.F.).
A change in the ratio I/H of a factor of ten yields a dB of 10.. by definition.
+3 dB is 2x IF
+6 dB is 4x IF
+10 dB is 10x IF
+20 dB is 100x IF
+30 dB is 1000x IF
etc
In your example 16x IF is 12 dB = 10*log(16)
However, the whole point of using dB to measure sound is that perception is not based on the "sound intensity factor". It is more similar to the dB scale.
Also, with regard to hearing loss:
http://www.gcaudio.com/resources/howtos/loudness.html
Alchymist
Member
Where is the discrepancy between our figures, Zak? I was saying the 10 dB was not 100X as originally posted, and using the +3, +6, +9 dB additives; and if you carry them out 18 dB= 64 times louder, and 21 db is 128. Your figures for 10 & 20 dB fall in between mine for each example, unlike the original post. Looking back, I suspect the original post had a typo for 10 dB.
And to be technically correct, we should be using dBA as a starting point.
And to be technically correct, we should be using dBA as a starting point.
Zak Smith
Member
The way you wrote the progression threw me off, sorry. We're saying the same thing.
Davandron
Member
10db is 10x, not 8x.
sarduy
Member
Alchymist
Member
Yes, I can understand why my approach would be somewhat confusing if you're used to working it out by formula. I worked in ECM for many years where RF power measurements were daily occurrences, and you get used to working with dB that way. It is really easy once you get used to it, just add and subtract the power levels. 
Alchymist
Member
Quote "10db is 10x, not 8x."
Who said it was 8X?
Who said it was 8X?
freakshow10mm
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My son ran off with my magazine, but the article was in a 2008 issue of Guns and Weapons for LE. The Navy wanted a suppressor for the M9, Walther P99, and MP5. DeGroat (armamentsales.com) won the contract and made/delivered several hundred to them in 60 days. The same ones they sell on their site are the ones they made for the military. They made extras to test the civilian market for suppressors. They are doing well so they are now in the suppressor business.Javelin said:
http://www.armamentsales.com/suppressors.htm
freakshow10mm
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According to the article, a DoD purchaser came to him first and asked if he could do it. The original contract was delivery in 120 days, then 90 days, then finally 60 days. DeGroat taught himself CNC code and the entire suppressor was built on his CNC mill, because he doesn't have a CNC lathe (at the time). He did the complete design, R&D, and full production in 60 days. That's astounding work and a job well done. Last he posted on Silencertalk he is buying one soon.
Yeah, I goofed. I meant to say 3db=2x change, 10 db=10x change, 20 db=100x change and so on.
Noise meters are able to weight their measurements in different ways. There are some good articles in Wikipeida that are worth reading. http://en.wikipedia.org/wiki/Decibel
Ranb
Noise meters are able to weight their measurements in different ways. There are some good articles in Wikipeida that are worth reading. http://en.wikipedia.org/wiki/Decibel
Ranb
Davandron
Member
Alchymist said:
You implied it was:
Alchymist said:
::shurg:: This is getting way outta hand. You were trying to help correct Ranb's mistake in good faith, and the way you were thinking about it is fine (you knew it couldn't be 100 because it was between 8 and 16), but by definition 10dB is a magnitude change. Why didn't you just say that?
Honestly, for a lay person it's not a big deal, but when you reference working in dB on a daily basis you're going to get your feet held to the fire.
Zak Smith
Member
Alright, enough on the dBs..
CoRoMo
Member
Should have known.
The reason you don't see them in movies or on TV is because Hollywood is incapable of reflecting reality.
lukepriebe
Member
PALMERJ said:
Unfortunately we can't all afford suppressors.
lukepriebe
Member
I'd rather spend the money on another gun.
My hearing protection cost me $30 and works for all my guns and everyone elses.
My hearing protection cost me $30 and works for all my guns and everyone elses.
freakshow10mm
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In Michigan you have to be an SOT to possess or make a suppressor. They are banned for civilian ownership.
chuckusaret
member
I have seen that chart many times. Some of the comments made point out that many people commenting on this subject have never been in a combat situation.
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