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- - Is this true? (http://www.professionalsoldiers.com/forums/showthread.php?t=8317)

Ok well heres the rumor
A buddy of mine has a friend who owns a para ordnance handgun. My buddy was able to put a couple of rounds through it, he says that it was so loud he couldn't hear. This I can understand, but than the kid whos handgun it was said that the noise is about the same as a suppressed M4. This I just can't take myself to believe. My friend told me to get some proof that the M4 was quieter so I am coming to you guys. Whats the real truth here?
Chris

Quote:

Originally Posted by cszakolczai

The guy who owns the Paraord is an idiot. I copied this from Surefire's website:

Quote:

Sound Science Made Simple.
The design went through several iterations as the sophisticated Danish sound machine told Dueck and Smith precisely what baffle arrangements worked better than others. Sound reduction, he found, was also dependent on atmospheric conditions. "We'd get one reading one day and another the next. Barometric pressure, temperature and humidity were all having an effect," Dueck said. "We had to test a given design a number of times under different conditions to get a meaningful reading."
After finalizing on the optimum design, the noise attenuation was rated at between 27 and 30 decibels (dB), reducing the sound of a 5.56mm to a handclap from an ear-splitting crack.

To appreciate how significant a reduction 30 dB represents, we need to understand how sound is measured. Most noise sources are measured in terms of intensity, or strength of the sound field. The standard unit of measure is 1 dB which is the amount of sound that is barely audible to the average human.

The decibel scale is logarithmic, meaning that each unit is 10 times that of the preceding one. For example, a noise source measuring 70 dB is 10 times as loud as a source measuring 60 dB and 100 times as loud as a source reading 50 dB.

A barely audible whisper measures 10 dB and a speeding express train rates 100 dB, although the train generates 10 billion times as much sound energy. This misleading difference can also be seen in earthquakes using the Richter scale, which is a logarithmic scale like the decibel scale. A magnitude of 5.3 on the Richter scale is a moderate earthquake, while a devastatingly strong earthquake has a magnitude of 6.3. Thus, like sound, a small difference in value actually means a great difference in intensity. "Reducing a gunshot by 30 dB makes it 1,000 times quieter. To put it another way, the sound of the action cycling - just the bolt clattering back and forth - is louder than the round firing," Dueck explained.

"Even a 14-inch barreled M4 can be safely fired indoors without damaging your hearing," the director of the Suppressor Division added. "This is a very significant tactical advantage."

Quote:

Originally Posted by rubberneck

The guy who owns the Paraord is an idiot. I copied this from Surefire's website:

I know Dueck and Smith.

Listen to them, they know what they are talking about.

Chris, I hate to break this to you, but your friend is an idiot. If your assessment is correct, everything he knows about firearms would fit in an empty .22LR case with room to spare.

TR

Quote:

Originally Posted by The Reaper

I'd be a wee bit more sarcastic in this statement, "everything he knows about firearms would fit in" ...... the indention in the base of a .22LR cartridge from the firing pin, with room to spare !!!

Later
Martin

From the Surefire article above.

"To put it another way, the sound of the action cycling - just the bolt clattering back and forth - is louder than the round firing," Dueck explained."

The cycling of the action will not be the loudest element in a suppressed rifle, the supersonic crack of the projectile will be quite more louder.

I think Barry was saying that the muzzle report is less noisy than the weapon functioning, not that the sonic crack is suppressed.

The sound of the sonic wave is perceived differently as well. Unless you are using sub-sonic ammunition, in which case he is correct as quoted.

The point that you bring up is an issue of semantics, not technical expertise.

TR

Quote:

Originally Posted by The Reaper

TR

Even if we not take in account the super sonic flight noise, i would say that the sound level of the action cycling is not at the 133-138 dB (A) SPL, that a M4 carbine with a 14.5" barrel exhibits at the muzzle with a quality suppressor.

And i usually dont get tangled up in semantics too much. And i am not trying to discredit Mr. Duecks expertiece in any way.

Quote:

Originally Posted by Tuukka

Tuukka:

All I can tell you is that when I have fired the M-4 with the SureFire suppressor, I can hear the bolt cycling and the trigger resetting. I have never observed that with the same weapon and ammo, but no suppressor. The proximity and conduction of sound may be the cause, but nevertheless, the fact that you can hear the action cycling when shooting with the can remains.

My experience may be limited, I have only fired a hundred thousand rounds or so through M-4s and a couple thousand through the SureFire suppressor.

The suppressor is rated at a measured 27-30 dB (A) SPL of suppression, what are you allowing?

TR

TR, the fact that the action noises come very clear is quite common with AR15/M16 series weapons, even the spring noise in the buffer tube comes quite clear.

The fact that a quality suppressor made with current suppressor technoloy, suppresses the SPL by around 27-35 dB, causes the action noises to come more evident to the shooter. An M4 unsuppressed is around 163-165 at the muzzle.

For reference, here is a brief clip, the weapon is a BM M4 with a 14.5" barrel, with one of our suppressors. Of course the true nature of the sound doesnt come away quite as it does in the real life but one can see a clear differene though.

http://www.aseutra.fi/english/product/AU.wmv

I

Quote:

Originally Posted by Tuukka

I agree, hard to tell sounds from the video.

Is your can supposed to vent gas upward from the rear of the suppressor-barrel interface? I have not seen that before.

TR

The mount does vent some gases out, the mount has been made to take in account tolerances in flash hiders. It could be made in a way that the rear is completely sealed. It does not affect sound pressure levels.

And what is the sound signature of an unsuppressed .45ACP from a 5" barrel?

TR

Quote:

Originally Posted by The Reaper

And what is the sound signature of an unsuppressed .45ACP from a 5" barrel?

TR

There are many variables of course which can result in somewhat different results but a .45 ACP sound pressure levels from a 5" run in the neighborhood of 160 dB.

The pistol calibres we primarily deal with are the .22LR and 9x19mm.

Thanks for all the responses, and tuuka, thanks for postin that vid. I've been searching everywhere for that. Something to show this kid. The kid who said that about the para isn't my friend just a kid who supposidly "knows his stuff."
Thanks again,
Chris

Anyone got video on the new Surefire suppressor? :munchin

I can host it if need be...