Ladies and Gentlemen,

Walter has gotten into making silencers, and all of us in here are half deaf, we are having a hard time deciding which round is louder than the other.

So, to stop all these arguments - which does not seem likely, taking these characters here! I have ordered a peak sound pressure meter, which goes up to 130 decibels.

Walter says he can scream that loud, and Maktoum is tellihg him he will make sure he does!

I just wanted to know if anyone knows what the sound level is of different rifles i when fired in the open.

We can check what it is like indoor ourselves.

Another point to argue about!!

Sure someone will post some convoluted formula but here's my take. Having owned lots of really loud obnoxious rifles launching big fast bullets and muzzle brakes - my observation is as follows:

NOTHING!! is as loud as a big black powder rifle out in the open except a bigger black powder rifle IE artillary piece. When we are on the 300M range which is basically a big canyon, the big bolt guns sound loud until someone lights off a 72 caliber BP cap lock!!! That's the kind of loud you can feel!!

Tell Walter I wish him good luck in building a silencer for one of those...........(wear a helmet and a flak jacket when testing)

I think they have been improving the gunpowder, as all guns nowadays seem to be much quieter than they were 30 years ago!

quote:

Originally posted by Macifej:
Sure someone will post some convoluted formula but here's my take. Having owned lots of really loud obnoxious rifles launching big fast bullets and muzzle brakes - my observation is as follows:

NOTHING!! is as loud as a big black powder rifle out in the open except a bigger black powder rifle IE artillary piece. When we are on the 300M range which is basically a big canyon, the big bolt guns sound loud until someone lights off a 72 caliber BP cap lock!!! That's the kind of loud you can feel!!

Tell Walter I wish him good luck in building a silencer for one of those...........(wear a helmet and a flak jacket when testing)

I think you will fit right in with this lot we have here!

You said a lot, but have not answerd my question!

Saeed,
That sounds like a great project.

Since there is a lot of controversy about muzzle brakes, it would be interesting to also test rifles with and without brakes, with the same load.

Oh yea the scientific theorem.

Larger projectile moving faster is loudest given all test samples either have or do not have a brake. Same shooter same sensor position etc. yada yada.

If I had to guess which shoulder fired rifle you might have laying around would be loudest I'd say....

Weatherby .378 with the brake on, 300 grain FN solid @ 3000 - 3200 FPS. (your meter won't be able to measure this one)

Maybe the 577 T-Rex loaded hot for the "No Brake" Catagory.

Of course it might make a difference as to what you are actually measuring and how as well.

There are lots of ways to measure "Loudness".

Side Bar -

One of my "Associates" told me of a situation where he was commading a group of Bradley FV's observing a live fire salvo from a group of Paladin 155's. They received a request via radio from the nearest 155 to "get inside your little armored car and plug you ears" before we commence firing or be permanantly brain damaged from the sound and shock wave.

I knew there was a reason I didn't sign up for the Army.

With handguns I clearly remember an incident years ago.We were at a range all shooting handguns and we were all used to the various rounds from 22 to 44 mag. Suddenly there was a tremendous loud ,piercing blast which seemed to go right through our ear protection !!! It was a then new Ruger revolver in 30 carbine ! Everyone put down their guns and asked 'what was that '!!

I gotta think that a gunshot is higher than 130 db.
I measured the noise level of M-60 tank engines and they were 170 db, right at the grill doors.

Don

My candidates for ear drum stretching are the 25-06 and the 264 Win Mag. For me, if you are behind them shooting it's not so bad but if you are beside them, they hurt.
Jim

Tests on the loudness of gunshots have been done before. When I was at a SCI convention, E.A.R., Inc. had a handout that listed the loudness of various types of firearms. You can read an article on the subject at this site:

http://www.americancopmagazine.com/articles/silenceIsGolden/index.html

It would appear that a decibel meter only going up to 130 won't be sufficient. The article indicates that even the lowly 223 Remington produces at least 150 decibels.

Also, since a decibel is on a logarithmic scale, 120 decibels is, for instance, a LOT louder than 110 decibels. Also, it's not just the loudness produced by a firearm that's offensive it's also the frequency of that noise.

The moral of the story, if you want to be able to hear your grandchildren talk, ALWAYS wear hearing protection when shooting even when hunting. If you can afford several $1,000 rifles, you should be able to afford hearing protection.

quote:

The moral of the story, if you want to be able to hear your grandchildren talk, ALWAYS wear hearing protection when shooting even when hunting. If you can afford several $1,000 rifles, you should be able to afford hearing protection

Speaking from experience. I always used protection at the range. However never thought of it when hunting and wing shooting. So protect your ears and wear something EVERYTIME you shoot or you will be like me spending $1000s to get help that I must wear ALL the time so I can now hear my Granddaughter.

Never ever fire a 454 Casull without ear protection! When deer hunting, a deer ran across in front of me and without thinking I pulled up and shot it without pulling my ear protection down over my ears. My left ear still rings. Good news is I got the deer, and my wife dosen't nag as much,(at least I don't hear her).

130 Db won't get you there. At least not measuring up close. The good part is that the SPL (Sound Pressure Level) decreases with the square of the distance. That means if you back off a little bit the results are directly calculable and proportionate for almost all sounds.

Tell Walter that he can't scream that loud unless someone comes after his privates with a propane torch.

quote:

Originally posted by Mark:
I think they have been improving the gunpowder, as all guns nowadays seem to be much quieter than they were 30 years ago!

Why ,Mark, I think you're right;however all I have to do is turn down my hearing aid. roger

Saeed ; Is this what your looking for ?

http://www.guns.connect.fi/rs/308measured.html

Shoot Straight Know Your Target . ...

Saeed, you have two problems here. One is that a 308 will go to about 170dB(C) without a muzzle brake and it may well approach 180dB(C) with a brake so your 130dB(A) (I'm guessing it is A weighted as most are) will not come close. The difference between the A and C weighting is probably not hugely significant in this situation but generally, and I'm not exactly sure why, C weighting seems to be preferred for recording the level of gunshots. This may relate to the possibility that with large field guns the C weighting would make a difference and so it may be a military standard for recording gunshot levels however this is merely a guess on my part.

The other problem which is less obvious and so more likely to introduce unexpected errors or strange results is that a gunshot has a very short peak duration. In order to record the peak of a gunshot you need a meter with a very fast response time indeed and a slower unit will give you wildly differing readings for the same actual SPL. Such meters are unlikely to come cheap and are unlikely to be generally available.

In short most commonly available meters are very unsuited to recording the levels of a gun shot and their results should not be relied upon unless you are sure they are suited to the job in hand.

I asked around a lot about this, I wanted a quiet-ish hunting rifle. nobody came up with any good data. sorry.

quote:

Originally posted by Mark:
I think they have been improving the gunpowder, as all guns nowadays seem to be much quieter than they were 30 years ago!

Good one.

muck

Gentlemen,

We will be checking rifles with silencers, so hopefully the 130 Decibels max level should be enough.

Does anyone know where we can get a meter that has a higher maximum measurement level?

Walter, in his infinite wisdom, started asking about what are the different "weighting" are.

Me "It is a measurement method they use"
Walter "Why do they call it WEIGTING then?"

Me "I have no idea Walter, so go bother Maktoum, I am busy!"

Walter "Maktoum, what weight should we put on this level meter?"

Maktoum "What eve meter?"
Walter "The one we are going to get"
Maktoum "Why do you want to put weight on it?"
Walter "Because it says you have to use these A weighting and C weighting. I don't know what the A and C are, and Saeed is no help, as usual, I thought you might know"

Maktoum "Let us put different weights on and see which one works best!"

Walter "A I am glad we geniuses think alike! What weight should we start with?"

Maktoum "I don't know, how heavy is this meter?"
Walter "I don't know, and I am not going to ask Saeed. He will get mad at me again!"

Absolutely unbelievable! I sometimes wonder how we manage to get ANYTHING done in here!

quote:

Originally posted by Grumulkin:

Also, since a decibel is on a logarithmic scale, 120 decibels is, for instance, a LOT louder than 110 decibels. Also, it's not just the loudness produced by a firearm that's offensive it's also the frequency of that noise.

a 3.2db increase is a doubling or 2X increase.

a 5db increase is a 4x increase

a 10db increase is a 10x increase.

But wait, it gets worse, far worse...

a 20db increase is a 100x increase
and
a 30db increase is a 1000x increase

Etc...



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quote:

Originally posted by Allan DeGroot:

quote:

Originally posted by Grumulkin:

Also, since a decibel is on a logarithmic scale, 120 decibels is, for instance, a LOT louder than 110 decibels. Also, it's not just the loudness produced by a firearm that's offensive it's also the frequency of that noise.

a 3.2db increase is a doubling or 2X increase.

a 5db increase is a 4x increase

a 10db increase is a 10x increase.

But wait, it gets worse, far worse...

a 20db increase is a 100x increase
and
a 30db increase is a 1000x increase

Etc...



AD

Does this apply to "weights" too?

OH Boy! We are going to have a field day with this once Walter gets into it!

I can just imagine me firing a shot and the meter scale goes over the top as Walter is holding it.

"Add more weight Walter"

He gets a 20 pounds bag of lead shot and tries to hold both the meter and the lead shot.

I fire another shot. The meter goes off the scale!

"Add 10X more weight Walter"

I love it

Will measure up to 190 db with upgraded microphone. Used for measuring Artillary etc.

Larson Davis 820

Made in USA so Don could pick one up and send it to you!! He has the extra cash with all those Oil Puts he's been closing out.

I have found different types of powders with the same bullet weight, same primer and same MV can have different noise levels, plus different recoil levele..

I always equated this to the chemicals that were used in their make up as the reasons why....

Sound waves are compressed air layered with less compressed air that is accelerated.

The least air can compress is 0 atmospheres.
The most it will compress, once the blast slows down to the speed of sound and forms a wave, is 2 Atmospheres.

So all gunshots with super sonic gas have a peak amplitude of two atmospheres in the near field.

The difference between a 50 BMG and a 22 short rifle sound at far field is the size of the super sonic gas ball at the time the wave is started.
The big gas ball has more low frequency content.

The low frequency will travel further and go around corners.


What does it all mean?
1) All guns have the same high frequency sound amplitude in the near field. Sound cannot get louder than cavitation. This is the same limit for power in acoustic cleaners.
2) The silencer or suppressor is going to need to expand the gas to less than 2 Atmospheres before bullet escapement.

What does all THAT mean?
The suppressor will have to be of a volume commensurate with the powder charge.


The last great AR thread on noisy gas from guns

quote:

Originally posted by Saeed:
... I have ordered a peak sound pressure meter, which goes up to 130 decibels...

Hey Saeed, If you want a "comparison" between firearms, you can measure the dbs with that meter "if" you simply move it off a slight distance. Since you all are going to be running the Test, then that distance is simply your choice, as long as it is far enough away not to Peg the meter.

Then you simply write the Comparison Data as, "XXdb measured at YYyds 180deg relative to the muzzle on flat, open land.", or however you all desire.

Since the values would be different for anyone running the Test depending on the lay of the land and position of the Meter, it should be good for any amount of debate a person would want to make.

Though it sure would be nice to have an Adequate Meter placed adjacent to where a person's ears are located at the time of firing.
-----

I'd "guess" the Largest Bores, burning the most Powder, which have the shortest Barrels will be the loudest.
-----

Always nice to be able to get an Engineering Joke - "Sound Weighting".

Perhaps you could convince Mr. Walter it was a mis-spell and it meant "Waiting for the Sound".

Best of luck on the Testing.

quote:

Originally posted by Hot Core:
If you want a "comparison" between firearms, you can measure the dbs with that meter "if" you simply move it off a slight distance.

Depending upon the location of the meter you may introduce the additional problem of the level of the supersonic crack made by the bullet passing. If the meter is an integrating unit, and the majority of commonly available units are to the best of my knowledge, then I would suggest that this might introduce a significant error which could not easily be corrected for. However, in view of the nature of the sound other more significant problems are likely to confound the process with such a meter.

quote:

Originally posted by caorach:
http://www.makeitlouder.com/Decibel%20Level%20Chart.txt

We are going to be testing rifles with silencers.

So I hope the 130 decibel range is plenty enough.

I've ranted on about this before Saeed but the EU guideline, actually knowing the EU it is probably included in 3475 laws including one governing the taste of chocolate, for an impulse noise is that the peak level must be below 140dB(C).

If the meter you ordered integrates it may be able to display a result of up to 130dB(C) but it may not actually be able to record a peak level this high. It is worthwhile therefore to take great care as with peaks such as gunshots your meter may be under reading by a considerable amount. To be relatively faithful I would estimate you need a meter with a response time of less than 25us and anything significantly slower may well give wildly varying results even on a shot to shot basis, certainly in free field.

As long as you are only doing it for a laugh then it should prove an interesting experiment but don't rely on the results to keep your hearing safe.

Some tests done on M4 with the shorter barrels in a .223 produced 164db in an unsurpressed mode. Can you imagine the noise level that would occur in a gunfight in Iraq if it was conducted indoors ( mud house ) with 3 to 5 fully automatic weapons being shot? Apprently there is some concern about the hearing health of some of our troops over there and there is a look toward providing more silcencers to them.

I had one of the first BOSS Browning models in a 22-250 and found that the prinicple of dialing in the barell harmonics worked great but the noise was absolutely deafening. I sighted the rifle in and produced some good groups in the .6-.8 range and went off coyote hunting with one of my sons. No coyotes, so on the way back to the truck after a long day flustrations were taken out on a jackrabbit that broked nearby from some cover. It was the first time I had shot that rifle without ear protection and it was so loud that my ears were ringing and so were my son's. I literally thought that the case had failed from the gases that were felt. I shipped the rifle back to Browning without firing another shot and they replaced it with a A-5 12 guage.

I had George Vais install a New Vais muzzle brake on a .300 Win Mag that I had and found that the noise increase was very small, like one or two db and the recoil reduction was super. George started working on silencers about that time and has come up with some great performing ones. See www.htgsilencers.com. I have one called the Universal that works on a .22 LR and for some light work on a .223. Just recently I added the Aris one for heavy duty use on a .223 with 33-37 bd reduction, which I haven't had a chance to shoot yet. I would recommend visiting his website and reading some of the articles posted there on his products. Good luck.

we had to do some tests to satisfy the county officials when we built our new rifle range a few years ago. if memory serves in an outside atmosphere 4' from the shooters side 308-136DB 223 128DB 38 spcl 92db 45acp 101 db 22lr 82db
the sound level decreases on a arithimatic progression the firing range was 300 yds from the nearest road and at that point nothing was over 40db

quote:

Originally posted by Saeed:

quote:

Originally posted by Allan DeGroot:

quote:

Originally posted by Grumulkin:

Also, since a decibel is on a logarithmic scale, 120 decibels is, for instance, a LOT louder than 110 decibels. Also, it's not just the loudness produced by a firearm that's offensive it's also the frequency of that noise.

a 3.2db increase is a doubling or 2X increase.

a 5db increase is a 4x increase

a 10db increase is a 10x increase.

But wait, it gets worse, far worse...

a 20db increase is a 100x increase
and
a 30db increase is a 1000x increase

Etc...



AD

Does this apply to "weights" too?

OH Boy! We are going to have a field day with this once Walter gets into it!

I can just imagine me firing a shot and the meter scale goes over the top as Walter is holding it.

"Add more weight Walter"

He gets a 20 pounds bag of lead shot and tries to hold both the meter and the lead shot.

I fire another shot. The meter goes off the scale!

"Add 10X more weight Walter"

I love it

But the values would be different if you use sand instead of lead shot or walnut shells for that matter ...

More to the point of the discussion, the Garand for instance was VERY loud at close to 170dB and a modern rifle also in '06 can be 30dB less at 140...

Also, as mentioned above, the difference in perceived hearing of a sound that's 3dB more is not twice as load but requires twice the "power" to produce... Good human hearing is sensitive to about 1dB increments but generally a 3dB in SPL is considered the "noticeable" difference between one sound and another... A-weighting is based on the human ear's response to sound where as c-weighting is simply peak sound level as mechanically measured...

Ken....

I believe a modern HP rifle is in the range of +-180 decibels. One of the worst I've experienced was the original Win. loaded 100-grain .264 Win. Mag. round. It was horrendous. I don't know if these are still that good or not.

I can get you any measurement you want from any source if I can control the reflection co efficient of the environment.

I read Cohen's 1956 book on loudspeaker enclosures in 1970, and he suggested that having more people standing around not only generally attenuated the sound, but changed the frequency emphasis.

I can remember in 1976 professor Ruben Siegelman teaching acoustics, and the only time he measured sound was with a calibrated HP microphone inside an Aluminum tube to find the standing wave ratio reflecting from spun glass at the end of the tube.
And he was looking for ratios, not absolute measurements.


What does it all mean?
You will not get reproducible measurement from sound meters in db re 1 u bar at various locations.
It is only for comparison.

I suppose I will now get the "most stupid, ignorant, rude, and uncalled for" for dissing some sound meter manufacturer.

I guess it is a sound "pressure" meter.
Maybe each cartridge should get it's sound level registered with SAAMI.

quote:

Originally posted by MikeN:
Never ever fire a 454 Casull without ear protection! When deer hunting, a deer ran across in front of me and without thinking I pulled up and shot it without pulling my ear protection down over my ears. My left ear still rings. Good news is I got the deer, and my wife dosen't nag as much,(at least I don't hear her).

Mike, you have just given me a heck of an excuse!

Well, here is some anicdotal evidence, but what the heck.

The loudest firearm I have every shot was an old short barreled Mini 14. It had a higher pitched blast than the .300 win mag, and everyone complained about the noise when I shot it.

Just an opinion, but I think there is loud as measured by a meter in dbs, and then there is painful loud as measured/perceived by the ear/brain.

The latter is the 357 Mag or 30 Carbine pistol, even the 10" 30 Herrett with 296 based loads.

Seead,
Be sure and try little 22 Jet, model 53 83/4" bbl, It feels like some one is sticking a needle thru both ears at the same time, the 30 Ruger carbine is not far behind.
Don.