sound suppressor

[Suputin]

Exactly what I was curious, because they also don't state from which direction this supposed sound reduction is coming from - such as the muzzle brake example you pointed out. Not to mention, is it measured from one spot - or many?

The Mil Std for sound measurement specifies measurements be taken 1 meter to the left of the muzzle, 1.5 meters off the ground. So thats exactly off the end of the muzzle.

I think you have to get the guy holding the sound meter to stand 3 feet in front of the muzzle at precisely the angle of the bore to the the target. This is why we have difficulty in setting precise sound level definitions in law, its almost impossible to get 2 readings under the same conditions! There's always some idiot screaming in the background for the second shot.

Someone around here has a sense of humour.

I am going to make a prediction that the following will kick of a huge fight.

I'm gonna correct a bunch of you at the same time. First off, sound has nothing to do with air movement.

Really so a pressure wave propogating through the air is not what creates sound?

In silencers the baffles do not slow or redirect the air they redirect the sound.

And where exactly do they redirect this sound to? So we can move the microphone to this new location and the firearm will sound just as loud as if it didn't have a silencer on it?

There are 2 types of silencers or mufflers. Absorbtive and reactive. Absorbtive silencers do just that, absorb sound. Common materials used are fiberglass, foam, rubber, cotton or steel wool.

Sure if you are talking about 1950's technology. I can assure you that NO modern western centrefire silencers use any sort of packing. How exactly do you think foam or rubber packing would survive the 800+ degrees created by full auto fire? You are also of course aware that steel wool burns at high temperatures? Not exactly good for silencers.

And how exactly does packing "absorb" sound? What is sound and how is it absorbed?

There is no such thing as an "absorbtive silencer". All silencers work in essentially the same way regardless of what materials are inside the tube. They trap and absorb ENERGY. Slow and reduce the energy release and you drop the perceived sound level of the shot.

Now in reactive silencers, baffles are used. These baffles redirect the sound back on it self, cancelling it out.

Bull####! There is no such thing as cancelling out a sound wave inside a silencer. Read "Firearm Suppressor Patents" for a detailed description of why.

Sound is nothing more than vibrations or energy.

Well thats the first correct thing you have stated.

How do I know this? Its what I do for a living.

So you design and test silencers for a living? If so might I humbly suggest you find a new career cause you don't know jack about this one.

I'm tired, going to bed.

Not a doubt in my mind about this one.

 

[cannonfodder]

MCbain,
Last time I checked, sound requires a medium to travel through. Seeing as how sound is energy and is incapable of being transmitted in a vacuum, what do you suppose the sound energy travels through here on earth? Right I would have answered air as well. So tell me then how air has nothing do to with sound suppressor technology?

Seeing as how the physics equation for calculatiung the velocity of a sound wave(or report)is 330 +(0.6t)= V Where the 330 is 330 metres/second constant, plus 0.6x current temperature(t) in degrees celsius. equals V or velocity of the report in metres/second. I guess this formula is uselss as air has nothing to do with sound or sound energy.

I would strongly advise you listen to suputin, he knows what he's talking about.

CF

 

[eltorro]

Suputin, It is true that the gases have little to do with the sound @ 100 yards - rather the bullet going thru air..... but I have one question.

Internally speaking - those gases have more than movemet to produce sound. Pressure and temperature have to be taken in consideration.

Somebody mentioned that the air trapped in the can (the oxygen more precisely) is prone to combustion and make a distinctive sound... reducing the efectiveness of the "thinghy".
Same source described that the whole problem could be overcomed if a "cold shot" is fired prior to deployment and then the can opening sealed with tape.
While keeping CO2 in the bbl/can is undeniably a good thing due to the sound propagation differences, I was a little distracted by the obvious opening on the inside of the muzzle. Can the air get in thru there?

The ones we were supplied with were mainly used as flash hiders, as the sole sound of the operation of rifle's mechanism was more than a "giveaway". It was actually preffered to have a gunshot than the distinct "kli-kank" if the "sound perceiver" was close.

but that is another story.

 

[Suputin]

Internally speaking - those gases have more than movemet to produce sound. Pressure and temperature have to be taken in consideration.

Correct

Somebody mentioned that the air trapped in the can (the oxygen more precisely) is prone to combustion and make a distinctive sound...

This is called First Round Pop and it is a real effect, where the first shot is louder than subsequent shots as a result of unburnt gases reigniting when they meet the oxygen rich atmosphere.

Same source described that the whole problem could be overcomed if a "cold shot" is fired prior to deployment and then the can opening sealed with tape.

Correct. The first shot uses up any oxygen in the can. Sealing the muzzle of the suppressor will slow the migration of oxygenated air back into the can.

While keeping CO2 in the bbl/can is undeniably a good thing due to the sound propagation differences, I was a little distracted by the obvious opening on the inside of the muzzle. Can the air get in thru there?

I'm not exactly clear on what you are asking here but the silencer is sealed onto the muzzle of the gun. The muzzle of the silencer is sealed by the tape and the chamber of the gun is sealed with the next round and the closed bolt. This is not a completely airtight seal so it will only last for a few hours.

The ones we were supplied with were mainly used as flash hiders, as the sole sound of the operation of rifle's mechanism was more than a "giveaway".

A fact most government anti types don't appreciate about silencers. They don't hide the fact a shot occured cause there are lots of firearm related noises that silencers do not affect.

 

[Airborn_69]

Heard it eats uo the insides of the barrel & crown..Prove me wrong?

 

[eltorro]

thank you, Suputin.

hollywood is mostly to blame for the misconceptions regarding the reality about supressors.

you can see guys all over shooting their oponents one by one without any sound at all. For those who believe that - get in a quiet room and cycle the action of the "easiest" one - the 10/22. If the sound doesn't get your attention.....

 

[Suputin]

Heard it eats uo the insides of the barrel & crown..Prove me wrong?

An improperly designed suppressor can cause erosion to the crown. Usually this is a result of the blast baffle (first baffle) being too close to the muzzle.

However a good suppressor can make a precision rifle considerably more accurate.