When a firearm is fired, what makes the "bang" and how do silencers work? nt

[ZombieHorde]

[provis99]

1. silencers are illegal. n/t

[slackmaster]

3. No, they're just heavily regulated

They are available in most states.

[thereismore]

6. That was not the question. nt

[Name removed]

7. Deleted message

Sub-thread removed by moderator. Click here to review the message board rules.

[ZombieHorde]

9. I am asking because I was playing a role-playing game called Shadowrun

and these little facts were important.

I wanted to cast a Silence spell on my rifle, but the game master said the spell would not work because the noise comes from the bullet breaking the sound barrier outside of the rifle. Once the bullet leaves the rifle the bullet would no longer be under the spell's effect. I then asked him why silencers work and he said he did not know.

[MercutioATC]

13. Tell him you're firing subsonic rounds.

http://www.corbins.com/subsonic.htm

[ZombieHorde]

15. I will. nt

[beevul]

29. No, not "subsonic" tell him your firing these:

Yeah, they're real:

http://world.guns.ru/ammo/sp-e.htm

[Orrex]

33. Tell him that the gun and bullets are silent because Dunklezahn said so.

[Callisto32]

18. No, you are just ignorant of the situation.

There is a difference.

[slackmaster]

2. The "bang" is mostly due to excess gas escaping after the bullet leaves

There is also sometimes a muzzle blast - Unburned powder burning in a flash after the bullet leaves.

Another component is "sonic crack" (small sonic boom) of a supersonic bullet, but that only applies to supersonic bullets and you have to be off to the side of its path to hear that.

Sound suppressors work by spreading out over time the release of the excess gas, so it's more of a whoosh than a pop. They work best with sub-sonic bullets, because those don't create a sonic crack.

[Robb]

4. ...

http://lmgtfy.com/?q=how+do+silencers+work%3F

[slackmaster]

8. As much as I love lmgtfy.com, the first link has a major blooper of a picture

Sound suppressors don't work very well on most revolvers, because there is a gap between the rotating cylinder and the barrel. Gas escaping through the gap makes a loud "Bang".

"Silenced" revolvers were used on the '60s comedy series Get Smart as a recurring gag.

:+

[Name removed]

10. Deleted message

Message removed by moderator. Click here to review the message board rules.

[Robb]

11. You have a better eye than me

...In my defense, I was distracted by the sheer dapper of the man's hat. :D

[slackmaster]

16. I'm a big fan of the whole Film Noir and hard-boiled look myself

:hi:

[Callisto32]

19. Actually, i think that may be okay.

It looks like a 1895 Nagant revolver, kinda. If it is, that revolver is a gas-sealing weapon, designed to avoid the barrel-cylinder gap. It is interesting, give it a google, and you will see what I mean.

[spin]

21. One possible revolver that a silencer would work on ...

is the Dan Wesson models. You could snug the barrel up against the cylinder tightly and install a silencer on the other end of the barrel. Never having tried this, I don't know how effective it would be. With an extremely tight cylinder gap, the amount of rounds you could fire would be limited.









I owned a Dan Wesson many years ago and it was extremely accurate. I'm still kicking myself in the ass for trading it.

[slackmaster]

22. I own a Dan Wesson .357 with 4 barrels and 3 grips, and love it

The standard gap is .002". The kit comes in a little briefcase and includes a feeler gauge and take-down tool.

[Hoopla Phil]

24. Nagant revolver?

I know, you said "most" but I couldn't resist.

[-..__...]

28. Ahhh... movie silencers.

I've always wondered how they came up with the walnut sized suppressor that screws inside the barrel and is more silent than an ant fart.

[jtuck004]

5. The "bang" is the powder burning very, very fast as it

exapands. Because everything else around it except the hole at the end of the barrel prevents the pressure from escaping, the pressure heads out the barrel, pushing the bullet ahead of it.

The sound you hear are the shock waves in the air of the burning propellant, the primer, the projectile leaving the barrel, etc.

The silencer absorbs those sound waves, and distorts or reduces the muzzle flash, though not usually as much as you see in the movies.

[lib2DaBone]

12. The Bang is the gunpowder exploding and the pressure blast out the barrel.

Silencers only work on Automatic Pistols, because you need a closed chamber to contain the muzzle blast, which is then directed into the silencer at the end of the barrel.

I guess they did make a silencer for one model of a revolver back in the early days... but a lot of flash seeped out around the cylinder because it was not a tight fit, so it wasn't very efficient. And it made the gun big and heavy.

You can own a silencer.. you just have to buy a federal permit to own one , and I hear that is expensive. (Ownership of silencers may have changed since we began losing our rights under the patriot act...but that was the way it used to be).

[DonP]

14. Actually it's a lot like a car muffler. Escaping gas ...

... is channeled through a series of hard and soft "baffles" in a tube, with a clear path for the actual bullet to pass. It slows the gas expansion as it leaves the barrel allows the gas from the fired cartridge to slow down and reduces the noise significantly. Most cartridges though produce a supersonic crack as they go out of the barrel and downrange anyway.

There is some subsonic ammunition that is quieter, with or without a suppressor. There are some I've seen in the military that can actually cut the noise on to where the mechanical cycling of the gun itself is louder than the shot.

On a side note ... I think it's Finland (?) that requires the use of suppressors for shooting range work or hunting near any villages or cities.

[X_Digger]

17. A suppressed 22 sounds like an old manual typewriter..

The clack-clack-clack of the bolt is almost all you hear.

[happyslug]

32. Actually a Muffler IS a Silencer, just design for an Gasoline Engine NOT a gun

The mechanisms is the same, an expansion area that contains the sound followed by a exit tube of about the same size as the entrance tube. The technology is the same, and even today silencers have been made from various mufflers for small engines (i.e. mostly lawn motor mufflers but others also).

[Glassunion]

20. Well several things...

"When a firearm is fired, what makes the "bang"" That is the sound of pure concentrated evil escaping all at once. Basically it's the sound of an angel's scream.

"how do silencers work?" They take a steel pipe and stuff it full of angel feathers, baby seal tails and panda bear knuckles. It muffles the sound of the aforementioned screams.

:sarcasm:

Good post, I'm sure someone who is not so much of an ass-hole as I am will be along shortly to answer your questions.

[ZombieHorde]

23. Funny. nt

[Hoopla Phil]

25. Shadowrun!!!?? Damn, I remember playing that back in 1990 LOL. OK, regarding silencers

from a person that has legally built 5 on ATF Form 1s.

There are lots of things making noise when a gun goes ban:

* Hammer strike - you know what this sounds like, just pull the trigger on an empty chamber. A silencer does nothing to stop that.

* Action noise - This is the noise that the bolt/bolt carrier makes when it cycles in a semi-auto and other repeating arms. A silencer does nothing to stop that.

* Chamber noise - Ever see a semi-auto fired at night? There is this flame coming out the side where the spent casing gets flung out. A silencer does nothing to stop that. Of course you can use a single shot, bolt action, or lever action. There is also the option of a Nagant revolver.

OK, now the stuff that a suppressor can muffle:

* Pre cursor pulse - this is the rapid woosh of are that the bullet pushes out of the barrel in front of the barrel.

* super sonic crack - this is the sound of the bullet breaking the sound barrier. Happens just a few inches to a couple of feet from the muzzle. More on this later.

* Bullet exit from the barrel - this is the big "bang" that makes the bullet go.

Your most quiet suppression will be a small bore (.22) sub sonic bullet fired from a single shot firearm. Your least quiet will be a large bore (.45 - .50) supersonic semi-automatic firearm. (all other variable equal - but that is not practical)

Different designs of silencers are of varying suppression levels do to any number of factors. Application, expense of machining, durability etc.

Consider a silencer designed for machinggun (ie. machine gun certified). It must have the ability to take a lot of gas from the multiple rounds fired. The gas builds up quickly and can cause a silencer not designed for it to burst or fail in some other way. Sooo, the trade off is not such good suppression qualities.

Also consider a silencer made to be the "ultimate" in quiet. It most likely will have sealed wipes at the end of the silencer. These wipes will wear out fairly quickly and need replacement often.

Supersonic bullets - rifle bullets travel at apx 2 to 3 thousand feet per second. (speed of sound is around 1200 fps depending on atmospheric conditions) This is like a jet going supersonic. Ever hear it? Could you tell where the jet was, where it came from, or where it was going from the sonic boom? (well if you having herd one the answer to those questions is all 'no') Granted a rifle is a 'bit' different but typically you visualize a 45 degree cone coming off the muzzle. Anything in rang and inside that cone may (depending on distance) be able to determine where the bullet came from. Anything outside that 45 degree cone may hear the sonic crack but will not be able to determine where it came from.

Game notes: If you tell your GM (game master) that you are using sub sonic bullets you two may need to reach an agreement on damage and penetration. Typically a rifle shooting sub sonics is going to be using VERY heavy bullets (200 gr and up) So you may agree to use the damage and penetration charts similar to a .44 special. I'm sure you get the idea.

I hope this helps and have fun!!!!

[ZombieHorde]

26. Fantastic replies! Thanks everyone! nt

[happyslug]

34. One thing most writers failed to mention is home made silencers

Once you understand how a silencer work, it is possible to make one at home. Remember a silencer is NOT design to stop the sonic boom of the Round itself, but the sound of the powder pushing the bullet down the barrel. Other have addressed the issue of the bullet, and the only way to reduce that sound is to go with sub-sonic bullets, but the sound from the powder can be reduced with a "silencer".

A Silencer works on the principal of slowing down the powder (By which I mean the SOUND of the Powder as it burns and rapidly expands and pushes the bullet out of the barrel) BEFORE it gets out of the weapon. This is done by providing a place for the powder to expand AND something for the powder to hit thus slowing the powder down. The simplest method is to tape a Soda-pop bottle at the end of the barrel and then pushing toilet paper (you want to avoid any flat paper, that just reflect the sound, you want something with some sort of "rough" surface that absorbs the sound). An exit hole can be made by firing a bullet (we are talking of a Plastic bottle). Being just tape you run the risk of the bottle going off with the bullet. Using paper you run the risk of the paper catching fire. But you will see a drop in sound. I have never tested such a contraption (It is an illegal device subject to a $200 tax due before it is even made so I have NEVER tested the above, but should work in theory). The bottle permits expansion of the Gases and the paper slows down the sound waves so that when they exit the bottle they are below the speed of sound.

Another variation of this is to use two bottles. The first a 12 or 16 oz bottle with numerous hoes cut into its sides. This is put inside a 2 liter bottle where the paper is kept. You still have a hole for the bullet to go through at the end of each bottle (Again the best way to "drill" that hole may be to fire a bullet through the bottles). Again the life expectation of such contraption is limited (maybe just a few shots) but should reduce the sound.

The Science behind silencer is quit simple, an expansion area filled with something that slows down the sound waves is what is needed provided both of above does not interfere with the path of the bullet.

[benEzra]

27. Geeky numbers, + videos.

The gas pressure behind the bullet in the first couple inches of its movement in a typical modern firearm is 35,000 to 65,000 pounds per square inch. The pressure drops as the bullet accelerates, but the pressure in the barrel behind the bullet is still in excess of 3,000 lb/in^2 (and possibly as much as 12,000 lb/in^2) as the bullet exits the muzzle.

If you were to suddenly vent a pressurized 3000psi scuba tank, the rush of escaping gas would be loud. Really loud. A firearm going off is loud for exactly the same reason---gases under very high pressure and exiting the barrel at supersonic speeds slam into stationary air and create hefty sound waves.

A sound suppressor catches these gases on the way out and makes them travel a circuitous route through baffles and holes in an expansion chamber, allowing the pressure of the gases to drop and their speed to decrease before they exit to the outside.

For centerfire firearms (i.e., larger than a .22), suppressed guns still make a fair amount of noise; it is just 20 to 30 decibels quieter than the same gun without a sound suppressor. So a suppressed centerfire rifle shooting regular ammunition will sound like a .22 rifle, still loud but not 165+ dB loud. Reduced-power subsonic loads and a very good suppressor can make a firearm sound like a high-powered airgun.

What a suppressed firearm *really* sounds like (not like in the movies):

http://www.youtube.com/watch?v=51AEuOts1YU&feature=related (.45 ACP pistol)

http://www.youtube.com/watch?v=VLW0eYp1Mso&feature=fvw (9mm pistol)

http://www.youtube.com/watch?v=gLjns9wIzDw&feature=related (this is a Federally restricted machinegun, not a civilian carbine)

http://www.youtube.com/watch?v=taL7Vmip39s (suppressed bolt-action rifle; it's still plenty loud with full-power ammunition, much quieter with low-gas subsonic loads)

[one-eyed fat man]

30. practical considerations

During Viet Nam the Army used the XM21, later M21 sniper rifle. It was equipped with a Sionics suppressor which was considered a very sophisticated design in 1969. It reduced the blast by roughly 46 dB.

At ranges beyond 200 meters, and especially at night when used with the AN/PVS-2 "starlight" scope made the sniper difficult to locate and very often allowed him to engage more targets.

Here's how that worked. If you have never been shot at by high powered rifles the first thing you hear (assuming the guy missed) is the crack of the bullet due to its traveling faster than sound. It sounds pretty much like the crack of a whip.

The next sound is the pop or thump of the weapon that fired the round. "crack...pop" or maybe "k--k--krack...th--th--thump" if it was a 3 round burst from an automatic weapon. Since you probably do not take kindly to being shot at, you will quickly determine from which direction the shooting has come and, with a little experience, based on the interval between the crack and pop a pretty good idea of about how far away the enemy is. And most important, if you knew roughly which directions fire was coming from, you knew which way to jump to get behind something that would stop bullets.

By reducing the muzzle blast, the enemy had a tougher job of determining which way to hide and it was apparent when you could see them through the night vision sights. If you started with the last guy in a column and worked forward you might hit two or three before they even figured out they were under fire. You do not want to push your luck. You do not get to retire if you shoot too often from the same spot, suppressed or not.

[Kaleva]

31. an explanation

The rabidly burning gunpowder and bullet traveling at high speed create a travelling wave which is an oscillation of pressure transmitted through the air and is composed of frequencies within the range of hearing. This causes your eardrums to vibrate which your brain then translates into being a gunshot.

[east texas lib]

35. The bang is actually produced by air rushing back into the barrel as the bullet exits the muzzle...

Silencers are really sound suppressors and as indicated up thread, function much like a muffler.