Author Topic: Subsonic means quieter... right?  (Read 10445 times)

Big Frank

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Re: Subsonic means quieter... right?
« Reply #20 on: December 12, 2008, 09:23:12 PM »
Anything under approx 1000 fps is subsonic

Anything under about 1100-1150 depending on who you ask.  ;) BTW, some ammo that's subsonic in a pistol is super-sonic in a rifle. Just something to consider if you have a pistol caliber rifle. But at least with a rifle the blast pressure is farther away you.
""It may be laid down as a primary position, and the basis of our system, that every Citizen who enjoys the protection of a free Government, owes not only a proportion of his property, but even his personal services to the defence of it, and consequently that the Citizens of America (with a few legal and official exceptions) from 18 to 50 Years of Age should be borne on the Militia Rolls, provided with uniform Arms, and so far accustomed to the use of them, that the Total strength of the Country might be called forth at a Short Notice on any very interesting Emergency." - George Washington. Letter to Alexander Hamilton, Friday, May 02, 1783

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Re: Subsonic means quieter... right?
« Reply #21 on: December 13, 2008, 08:15:12 AM »
The speed of sound at sea level, considering 72 deg F, is 1131 fps +/- a skinch.....several factors change the value like altitude and temperature.

T

PegLeg45

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Re: Subsonic means quieter... right?
« Reply #22 on: December 13, 2008, 10:34:03 AM »
The speed of sound at sea level, considering 72 deg F, is 1131 fps +/- a skinch.....several factors change the value like altitude and temperature.

T

What the hell's a 'skinch'?....Anything like a cat-hair or 'smidge'?     ;D
"I expect perdition, I always have. I keep this building at my back, and several guns handy, in case perdition arrives in a form that's susceptible to bullets. I expect it will come in the disease form, though. I'm susceptible to diseases, and you can't shoot a damned disease." ~ Judge Roy Bean, Streets of Laredo

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Re: Subsonic means quieter... right?
« Reply #23 on: December 13, 2008, 10:44:16 AM »
What the hell's a 'skinch'?....Anything like a cat-hair or 'smidge'?     ;D

Exactly like a cat-hair... smidge....little bit......tad....iota....itty bitty...or the Grinch's sister, Skinch..... :D

PegLeg45

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Re: Subsonic means quieter... right?
« Reply #24 on: December 13, 2008, 10:48:28 AM »
Exactly like a cat-hair... smidge....little bit......tad....iota....itty bitty...or the Grinch's sister, Skinch..... :D

"How The Skinch Stole Christmas"...sounds like a bad truck-stop story to me........... ;D
"I expect perdition, I always have. I keep this building at my back, and several guns handy, in case perdition arrives in a form that's susceptible to bullets. I expect it will come in the disease form, though. I'm susceptible to diseases, and you can't shoot a damned disease." ~ Judge Roy Bean, Streets of Laredo

For the Patriots of this country, the Constitution is second only to the Bible for most. For those who love this country, but do not share my personal beliefs, it is their Bible. To them nothing comes before the Constitution of these United States of America. For this we are all labeled potential terrorists. ~ Dean Garrison

"When it comes to the enemy, just because they ain't pullin' a trigger, doesn't mean they ain't totin' ammo for those that are."~PegLeg

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Re: Subsonic means quieter... right?
« Reply #25 on: Today at 01:22:50 AM »

MikeO

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Re: Subsonic means quieter... right?
« Reply #25 on: December 13, 2008, 10:51:12 AM »
Even subsonic ammo can damage your hearing. There is a big difference between outdoors and indoors, size of the room, where you/others are at in relation to the muzzle, etc.

Not noticing/being aware of the noise does not prevent the damage either. Stress/auditory exclusion can't be counted on to protect your hearing. One shot could damage your hearing for life, or not. One person might be able to get away w emptying a mag indoors w no/little damage, and another may be going "eh" the rest of their life after one shot.

Damage can be cumulative too. Not using enough hearing protection for a long time can damage your hearing as much as none one time.

Gunfire Noise Level Reference Chart

Below we have listed critical data describing peak sound pressure levels produced by firearms used in shooting and hunting sports. A serious byproduct of this exposure is sensory-neural hearing loss, which cannot be restored to normal. With the introduction of MUZZLE BRAKES and PORTING, the risks of hearing loss dramatically increase. Use this chart as a reference guide for promoting the need of using adequate hearing protection.

Notations
Keep in mind that conversational speech is approximately 60-65 dB, and the threshold of pain is considered to be 140 dB. According to Dr. William Clark, Ph.D. senior research scientist in charge of the NOISE LABORATORY at the Central Institute for the Deaf in St. Louis, the damage caused by one shot from a .357 magnum pistol, which can expose a shooter to 165 dB for 2msec, is equivalent to over 40 hours in a noisy workplace. Dr. Krammer, Ph.D., Ball State University, Muncie, Indiana has documented the following pressure levels.

Table 1. SHOTGUN NOISE DATA (DECIBEL AVERAGES)

.410 Bore 28" barrel 150dB
26" barrel 150.25dB
18" barrel 156.30dB
20 Gauge 28" barrel 152.50dB
22" barrel 154.75dB
12 Gauge 28" barrel 151.50dB
26" barrel 156.10dB
18" barrel 161.50dB 

Dr. Krammer continues to say that shotgun noise averaged slightly more that 150dB. This is approximately 14dB beyond the threshold of pain, and more than sufficient to cause sudden hearing loss with complications.

Table 2. CENTERFIRE RIFLE DATA

.223, 55GR. Commercial load 18" barrel 155.5dB
.243 in 22" barrel 155.9dB
.30-30 in 20" barrel 156.0dB
7mm Magnum in 20" barrel 157.5dB
.308 in 24" barrel 156.2dB
.30-06 in 24" barrel 158.5dB
.30-06 in 18 _" barrel 163.2dB
.375 18" barrel with muzzle brake 170 dB

Krammer adds that sound pressure levels for the various pistols and ammunition tested yielded an average mean of 157.5 dB, which is greater than those previously shown for shotgun and rifle noise levels. There was also a greater range, from 152.4dB to 164.5dB, representing 12 dB difference, or more than 10 time as much acoustic energy for the top end of the pistol spectrum. It should be noticed that this figure of 164.5 dB approaches the practical limit of impulse noise measurement capability inherent in most modern sound level meters.

Table 3. CENTERFIRE PISTOL DATA

.25 ACP  155.0 dB
.32 ACP  153.5 dB
.380  157.7 dB
9mm  159.8 dB
.38 Spl  156.3 dB
.357 Magnum 164.3 dB
.41 Magnum  163.2 dB
.44 Spl  155.9 dB
.45 ACP  157.0 dB
.45 COLT  154.7 dB

The above averages are for all types of ammunition used in these firearms, and should be considered fairly representative. No wonder we hear numerous reports about hearing loss as a result of firearms including acoustic traumas that take hearing completely as a result of one shot. Imagine what the noise levels must be when we incorporate muzzle brakes or porting into firearms, or have a gun explode near the ear due to malfunction.

OUR WARNING IS SIMPLE AND IS IN THE BEST INTERESTS OF EACH SHOOTER. AS THE SOUND PRESSURES INCREASE, SO DOES THE RISK OF PERMANENT HEARING LOSS. IF YOU INCORPORATE A PROCEDURE INTO YOUR SHOOTING THAT INCREASES THE SOUND LEVEL, YOU ALSO INCREASE THE RISK OF HEARING LOSS TO YOURSELF AND POSSIBLY THOSE WHO STAND NEAR YOU. BE SURE TO USE ADEQUATE EAR PROTECTION WHEN USING A FIREARM AND BE CAREFUL OF THOSE NEARBY. LAWSUITS HAVE ALREADY BEEN RECOGNIZED FOR GUNFIRE NOISE THAT HAS RESULTED IN HEARING LOSS. ALWAYS CONSULT A PROFESSIONAL AUDIOLOGIST, OTOLOGIST, OR OTOLARYNGOLOGIST WITH YOUR HEARING PROBLEMS. Hearing loss is not fun and can be prevented.

Compliments of http://www.earinc.com/




TSB

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Re: Subsonic means quieter... right?
« Reply #26 on: December 13, 2008, 11:29:25 AM »
"How The Skinch Stole Christmas"...sounds like a bad truck-stop story to me........... ;D


Never, ever let your Skinch get ahold of your credit card...They won't steal X-Mas...they will BUY it...!!!


P.S.  Thanks 1st Sergeant, MikeO

tombogan03884

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Re: Subsonic means quieter... right?
« Reply #27 on: December 13, 2008, 11:48:52 AM »
That was VERY interesting MikeO. Thank you for posting it.

 

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