Questions about: Noise, Barrels and Porting

[VFX_Fenix]

Get real. So I guess you would say it's the super sonic pop of the "cork" leaving the champaign bottle.
So it isn't the 12000-15000 psi of chamber pressure behind the .223 .62gr bullet that makes the noise.
If your ever have the oppertunity to have bullets fly over your head. You will hear just wispers, little sweat somethings. Not cracks, booms or anything like that. At a distance of a few hundred yards. Because the bullet will be threre long before the noise from the explosion of the gases. They cut through the air like a knife and do not create sonic booms like a jet. They could due to the speed if they displaced the amount of air that a jet does, but they don't. The noise you here is the gasses escaping when the bullet leaves the barrel. You are correct though. Sub sonic rounds like from a small cal pistol are easier to silence. That is because of their smaller chamber pressures and less gas.

No, the Champaign noise is caused by escaping gasses and I'm sure that no cork has ever been clocked traveling over 1000-ish fps.

Try this one on.

http://guns.connect.fi/rs/AUG.html

Please, note: No suppressor is able to eliminate ballistic "crack" of supersonic bullet, but noise of report towards the shooter is usually not louder than snap of .22 rimfire rifle, shooting Hi-Velocity .22 LR cartridges. Using custom-loaded 5.56 x 45 mm subsonic rounds (muzzle velocity ca. 300 m/s) the noise of the shot is not very much more audible than is the hammer click of a dry-fired rifle.

Any projectile (or object) traveling faster than sound that has a significant displacement will cause a sonic boom (in atmosphere) because of the pressure differencial built-up on the object as it passes through the air. This is why whips crack, why Helocopters get quieter the more blades they have on their main rotor, why Jets make huge rackets when they're traveling at hypersonic speeds, and why supersonic bullets fired from suppressed weapons still have a report in the nieghborhood of 130-ish db.

I'm guessing that all the bullets you've ever had flying over your head were all the subsonic kind and so the noise of the bullet traveling overhead can't be heard over the report of the weapon that shot them.

Swing a stiff wire through the air, or even better, a saber. If you swing it fast enough, you'll hear it "cutting" the air.


EDIT: It should be noted that some of the quietest suppressed firearms are in relatively large caliber, namely 9mm Para and .45 ACP, in the MP5-SD and Mk23 SOCOM.

[REDRT]

No, the Champaign noise is caused by escaping gasses and I'm sure that no cork has ever been clocked traveling over 1000-ish fps.



I'm guessing that all the bullets you've ever had flying over your head were all the subsonic kind and so the noise of the bullet traveling overhead can't be heard over the report of the weapon that shot them.

No they were from M16s in the service. Standing down range in the target pits. The bullets reach the trarget long before the report of the sound from the muzzle. Bullets do not make a sonic boom passing just over head. Also that holds true here in Wisconsin during the gun deer season. Bullets have passed right on by me without making loud sonic booms before I heard the report from the muzzle. I'm sure I could prove this to you safely if you would be willing and close enough to me. Dig you a nice fox hole. Little whisper as the bullet passes on over head even at super sonic speeds.

[VFX_Fenix]

No they were from M16s in the service. Standing down range in the target pits. The bullets reach the trarget long before the report of the sound from the muzzle. Bullets do not make a sonic boom passing just over head. Also that holds true here in Wisconsin during the gun deer season. Bullets have passed right on by me without making loud sonic booms before I heard the report from the muzzle. I'm sure I could prove this to you safely if you would be willing and close enough to me. Dig you a nice fox hole. Little whisper as the bullet passes on over head even at super sonic speeds.

The Sonic boom in that case is mixed with the report of the rifle, the reason the bullets don't make a noise as they pass you is because they're traveling, get this, faster than sound. The sound waves they're generating won't reach your ears until after they've passed. This is also true of jets when they're traveling at hyper/supersonic speeds.

The bullet only technically makes a single boom, after it's traveling faster than sound the shockwave that it generates can only travel as fast as sound will carry it and the bullet will remain infront of the shockwave it generates until it slows down enough for its wake to catch it. If you're in a jet that's traveling at hypersonic speeds you won't notice anything change in the noise the jet makes, however people on the ground will get an unpleasant wake-up call once the wake reaches them.


*------------------ <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<||||||||||||||||

^Bullet ------------ ^Sound wake (noise the bullet makes while moving through the aiir) ^Rifle Report(dashes are for spacing)

The farther from the origin on the bullet the longer the lag time between the arrival of the bullet at the arrival of the report, also the faster the bullet travels the longer the lag time.

The point is that a large part of the noise a firearm shooting hypersonic ammon generates IS from the bullet going hypersonic and generating a sonic boom. For this reason a Silencer cannot suppress this and so Hypersonic ammo will always have a significant report when compaired to the same firearm shooting subsonic ammo reguardless of caliber. You could concievably put a suppressor on a Howizter with a subsonic load and you'd only hear the action and the projectile leaving the barrel.

EDIT: The crack of the sonic boom is the object punching through the pressure build-up it produces on its trailing egde. Once the pressure build up is broken through the projectile won't make another sonic boom.

[bjjb99]

Have you ever had a bullet fly just over your head? The projectile doesn't make a distinctive crack . More like a wisper. The crack is the gasses violently escaping for behide the projectile exiting the the barrel. Accually a paintball flying just past your head has more noise because of it's size causing more drag than a bullet like a .223 flying at speeds over 2000fps.

While I've not had a bullet fly "over my head", I have had several hundred pass in front of me at a distance of about a hundred yards. I had the wonderful opportunity to be an observer during a live fire M2 .50 caliber test, standing about 500 yards downrange from the weapon and about a hundred yards off to one side.

The testing took place at night, using tracer rounds. Single shots from the M2 would result in a single tracer travelling downrange. As the tracer passed in front of our position, we would hear a loud "snap" or "crack", followed about a half second later by the report of the M2 itself.

The first report was from the supersonic bullet passing by our position. The second report was from the M2. Note that these were clearly not echoes of each other, but rather two very different sounds.

Short bursts were even more interesting, as we'd hear "snap snap snap snap snap" followed shortly by "boom boom boom boom boom".

BJJB

[REDRT]

A normal 1911 chambered in 45acp standard 230gr load it's velocity is under the sound barrier ie subsonic. According to Fenix I guess there shouldn't be any noise. Yet there is a good size boom. That boom is caused by the gasses escaping from behind the bullet leaving the barrel. Just like my cork from the bottle example. Just as it is in a rifle shooting at higher velocities. Believe what you want to believe, I'm done. Too many ignorant people these days. This post is about paintball anyway. The air or CO2 ie gasses behind the paintball, the vibration/harmonics of the barrel and the mechanical operation of the bolt cycling all combined is what we here. You have a barrel that doesn't chime like crystal (tin tin tin), a good paint to barrel match so limited gas escapes around the ball, controlled porting venting off the gas in a set time ie fps vrs barrel length. One can have a pretty quiet marker

[VFX_Fenix]

A normal 1911 chambered in 45acp standard 230gr load it's velocity is under the sound barrier ie subsonic. According to Fenix I guess there shouldn't be any noise. Yet there is a good size boom. That boom is caused by the gasses escaping from behind the bullet leaving the barrel. Just like my cork from the bottle example. Just as it is in a rifle shooting at higher velocities. Believe what you want to believe, I'm done. Too many ignorant people these days. This post is about paintball anyway. The air or CO2 ie gasses behind the paintball, the vibration/harmonics of the barrel and the mechanical operation of the bolt cycling all combined is what we here. You have a barrel that doesn't chime like crystal (tin tin tin), a good paint to barrel match so limited gas escapes around the ball, controlled porting venting off the gas in a set time ie fps vrs barrel length. One can have a pretty quiet marker

REDRT - Please note that there are three, count them three, sources of noise generated by firearms and airguns (paintball guns included).

1) Action (mechanical noise made by the firearm itself from hammers/strikers/etc.)
2) Expanding Gasses (Burning powder makes expanding gasses which push bullets down the barrel)
3) Projectile Noise (Sonic Boom in hypersonic ammo and things just moving through the air)

In Firearms two of these can be controlled, Expanding gasses through the use of a sound suppressor, and Projectile noise (using subsonic ammo). The noise generated by the action of the weapon will always be contributing to the noise of firing however the action sound is insignificant when compaired to the noise generated by the expanding gasses and projectile itself IF the projectile is of the hypersonic flavor, subsonic ammo again will have a negligeble contribution to the total loudness of the weapon's report.

And yes, a .45 ACP Shooting 230gr Ball WITH A GOOD SILENCER will make very little noise.

[REDRT]

This is over for me. I unsubscibe to this thread. Argueing this is pointless Fenix because I can't plug in to the matrix and show you just how wrong you are via my personal experiences... Go on believing your going to hear that bullet flying on in sonic booming all the way. Maybe your fast enough to dodge it to...

[VFX_Fenix]

This is over for me. I unsubscibe to this thread. Argueing this is pointless Fenix because I can't plug in to the matrix and show you just how wrong you are via my personal experiences... Go on believing your going to hear that bullet flying on in sonic booming all the way. Maybe your fast enough to dodge it to...

You're still missing the whole "This weapon has a silencer on it thing" I'm guessing... In every case you've come up with a scenario that would lend support to your position the objects in quiestion have always been from non-suppressed sources.

Champaign bottle/cork
M-16
1911 Gov. .45ACP

And only one of them was actually firing a hypersonic round (M-16).

I had a thought that perhaps the reason you weren't hearing the projectile was because after traveling XXX yards it had dropped into the subsonic realm, however even at 500yards a 62gr. .223 Rem bullet it still idealy traveling faster than sound, I suppose you could be hard of hearing... kidding.

Anyway, Suppressors in action, you guys know you love movies, right?

Movie
From this page

Here's another one from Wikipedia

Wikipedia

Supressors and Silencers

No supressor can completely eliminate the sound of firing a firearm. Even subsonic bullets make distinct audible sounds simply flying through the air and hitting targets, and supersonic bullets produce a sonic boom shockwave as well with a much louder crack. Semi-automatic firearms also make a distinct noise as their action cycles, ejecting the old empty cartridge and loading a new one....

and

Ammunition for use with suppressors

Suppressors are most effective when the bullet's velocity does not exceed the speed of sound. A bullet that breaks the sound barrier creates loud flight noise, or a "sonic boom". For any further increase in velocity higher than the speed of sound, flight noise does not increase significantly. Supersonic flight noise may be reduced somewhat by using a projectile of smaller caliber. Bullets that travel near the speed of sound are considered transonic, which means that the airflow over the surface of the bullet, which at points travels faster than the bullet itself, can break the speed of sound. Pointed bullets which gradually displace air can get closer to the speed of sound than round nosed bullets before becoming transonic.

So where does this leave us? Answer, with two people convinced they're right, one of which has given up based on personal experience (which is valid). However I personally am more inclined to believe what I learned in school, what has been validated by at least one suppressor company, and what my intuition tells me.

So, now that I'm absolutely sure this thread is dead, not coming back, that it's lost ALL direction of where it was going, I'll umm... just take a hint and wander off to do some homework since I ain't got nuthin' else to do.