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Durkin Tactical Franklin Armory
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Posted: 6/11/2002 9:15:09 PM EDT
When useing subsonic ammo do they cool the gases from the bore, closer to the outside temp.?
Link Posted: 6/11/2002 10:26:21 PM EDT
The suppressor muffles the sound of the spent gas behind the bullet.  This will reduce the "bang" sound that is heard. Although you may hear a report, the suppressor changes to sound signature so that the report can not be immediately recognized as a firearm discharge. This also helps to hide the shooter, due to the sound of the report/sonic boom appears to originate well in front of the shooter(point of origin).

The subsonic round will prevent the round from making the cracking sound that the bullet would make if it broke the sound barrier as it traveled down range.  The burning temperature has nothing to do with the round being loaded to keep it's FPS below the speed of sound.

The thing to remember is that there are two sounds made by a firearm discharge.  The first being the report, the second being the sonic booms that the bullet makes breaking the sound barrier.
The way to think of it is if you suppress a 308, you lose a lot of the boom, but the round still makes a lot of noise going down range.  If you suppress a round like the subsonic 22LR, then all you hear is the whoosh from the suppressor, then the whomp of the round striking the target.
Link Posted: 6/11/2002 10:36:25 PM EDT
Thanks for using your 556 post for this, but I understand the bullet making the sonic boom. What makes the report? Hot air colliding with cool (a gun seems to be louder the colder it is, I have no scientific to back this) or is it the gases going at supersonic speeds?
Link Posted: 6/11/2002 10:39:46 PM EDT
Its the collision of Warmer gas coming in contact with the cooler air. Atleast in the case of sub-sonic ammo.
Link Posted: 6/12/2002 12:34:39 AM EDT
How a suppressor reduces the apparent sound of a gunshot is rather complicated he
A simplified explanation would be;
Suppressors reduce the amount of energy contained in the hot and extremely turbulent expanding combustion gas stream that pushes the bullet out of the barrel. Since muzzle bast is in essence- a hot, burning, expanding, and turbulent high velocity air mass mixing with cooler non-turbulent atmosphere creating a pressure wave. What we perceive as sound is a pressure wave (energy), suppressors reduce the amount of energy in that wave by various means including the use of aerodynamic chambers and baffles to increase the amount of turbulence  (mixing and delaying the gas from exiting the suppressor, thus allowing the gas to cool, heat is transferred to the air inside of the suppressor, and the metal suppressor body itself.)
The more heat you take away from the gas while the gas is trapped in the suppressor, the quieter the suppressor is perceived. Many suppressors use "wet technology", by using liquid (such as water) or grease to aid in cooling the gasses by evaporation. Wet suppressors are generally the quietest types, but require the liquid or grease to be replaced often as performance degrades as the liquid or grease evaporates.
So the answer to your first question is- YES
As to whether or not the gasses are subsonic, transonic, or supersonic, that depends on the round being fired and the atmospheric conditions.  Supersonic rifle suppressors work in same manner as described, but have a lot more energy (turbulence, heat,velocity, and momentum as the gas tends to have more mass due to the unburnt and burning powder, along with its by products.)
Link Posted: 6/12/2002 5:40:29 AM EDT
It's magic.

Link Posted: 6/12/2002 7:13:23 AM EDT
Remember your Physics Classes and the Perfect Gas Law, PV=mRT? The simplified form use is (P1*V1)/T1 = (P2*V2)/T2. To supress noise, P2 needs to be close to local atmospheric pressure to make exit gasses subsonic. A supressor plays with V2 and T2 to make that happen. P1, V1 and T1 are a function of the cartridge being used and barrel length. Same law works for compressors, engines mufflers, gas turbines, windmills and lots of other stuff.
Link Posted: 6/12/2002 9:10:06 AM EDT

You know, I'm starting to doubt you actually own that. . . I mean, I have that EXACT SAME pic on my computer. . I could start posting it in every thread too:-P.

-J/K. Keep up the good work.

My dealer informed me monday that KAC FINALLY accually got the autorization back and shipped mine monday. So, it's supposed to be here ANY DAY NOW. . . and I can FINALLY send in the 2nd set of paper work. Geez, this is a huge PITA. I hope it doesn't take ANOTHER 3 months! Anyhow, it better be as good as you say it is!

Oh, and to answer Ridge Runner:  All the things posted so far are correct, but I wanted to add that another thing some of the new surpressers do is harmonics shifting. They will resinate the sound to a different frequency, so the human ear can't hear it, but it may still be just as loud. I.E., it's REALLY LOUD to your dog, even though you don't hear much.

Also, sorta mentioned, one thing they all do, is simply slow the air down. . . . that eliminates the popping sound created when the fast air hits the slow air. Like they said, theres a LOT of diffrent things and methods supressors do/use: Heat (air and water cooled), frequency, speed, ect. . .

Link Posted: 6/12/2002 9:31:46 AM EDT


Link Posted: 6/12/2002 1:44:38 PM EDT
hmmm. . . Ok, I believe you now. I didn't have those last 2 pictures (YET).

What rifle and can is that in the last pic? -How's that shiny supressor work with the camo rifle?                                            

I've been thinking about getting an AWC leatherneck "m40a2" with the AWC thundertrap surpressor. . . . I just don't know if I can stand the wait.

Link Posted: 6/12/2002 1:54:32 PM EDT
That's a Ruger 77/22 with AWC Archangel III.  I took the tape off the suppressor for illustrative purposes.

AWC did the shortening, threading and trigger on this rifle.  It's SWEEEET.
Link Posted: 6/12/2002 3:10:33 PM EDT
QuietShootr, you need to hook me up with a good Class 3 dealer here in Indiana. I have been putting off going Class 3 for long enough. Sound suppressors would be the cheapest place to start. I have been agonizing over purchasing a H&K USP45 Tactical for awhile now. Please e-mail me and provide me the name of a good Class 3 dealer (hopefully not too far away) and give me the specifics on your suppressor. Thanks!
Link Posted: 6/12/2002 4:41:14 PM EDT
Brian Allen at Sunset Weapons is the MAN.


He's in Danville.  If we get this Indiana AR15.com get-together going you'll get to try out some of my stuff!
Link Posted: 6/12/2002 6:21:50 PM EDT
howl dose spelll checz wrokes?
Link Posted: 6/12/2002 6:35:33 PM EDT
Link Posted: 6/14/2002 1:45:07 PM EDT

Brian Allen at Sunset Weapons is the MAN.


He's in Danville.  If we get this Indiana AR15.com get-together going you'll get to try out some of my stuff!

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