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Suppressor Science

    I have heard all kinds of names associated with these devices. I will consider "cans" the cheap contraptions some manufacturers are coming out with! Even supposedly known "brand" name sound suppressors (the correct term) are considered as "cans" by me, since they are a disgrace to the science. I will leave "mufflers" to the automotive shops and a very well known "gun muffler" manufacturer with Military contracts, their construction being notoriously ephemeral and their quality very questionable.

    Seriously, I recently had a visit from a very concerned Commander from the unit that secures NASA, training with his Team here in South Texas enquiring about a "fix" for their "mufflers" (from the above mentioned manufacturer) that have the tendency to follow the projectile, breaking away from the rifle and falling off the training tower to the grassy pasture below! I cannot help comparing these with the synonymous automotive parts found in poor neighborhoods road ditches. Yes! They can clearly call their devices "mufflers".

LionE300
Click to see our "Lion" Carbon Fiber Suppressor

    "Silencers" is a misleading term, since there will always be some kind of noise from the action of the firearm, the 'hit" of the hammer or striker to the firing pin etc. Other solutions have emerged for clandestine weaponry (see our "EXOTIC FIREARMS" page) but even these create some kind of noise.

    That leaves us with the term "sound suppressors".

UNDERSTANDING SOUND SUPPRESSORS

    When a firearm fires, creates a sound that is a combination of 3 elemental components :

  1. The muzzle blast created by shock waves produced from the violent expansion of gases generated by the instantaneous burning of the propellant (gun powder) as they meet the atmosphere at the muzzle of the barrel, preceding and following the projectile (bullet).
  2. The breaking of the sound barrier (sonic "crack" or "boom") produced from anything (in this case a bullet) travelling in the atmosphere at a velocity faster than the speed of sound (1,085.5 feet per second at 32 degrees Fahrenheit). When calculating speed of sound in many media varies as the square root of the temperature and the media's atomic weight. By dealing with air with almost constant molecular weight, this factor is not really relevant or at least to the point that will not make measurable difference. Also contrary to popular belief, altitude and humidity have no effect on the speed of sound. When the projectile (bullet) travels at a speed lower than the speed of sound does not produce "sonic boom" as it passes stationary or moving objects.
  3. The sound created by the mechanical parts of the action of a semi automatic or fully automatic weapon. There have being techniques devised to reduce or eliminate the sound of the moving parts of the firearm but still is no such thing as an obsoletely silenced gun (someone please advice Hollywood). That is the reason that the nomelecture of the device is "suppressor" over "silencer".
S4M silent pistol

    Obviously the most successfully suppressed firearm will be one with no reciprocating action parts, mainly a single shot (or derringer, see "EXOTIC FIREARMS") and we still have to take in consideration the distinct sound of the trigger group and the hit of the hammer on the firing pin ( next time you "dry fire" a gun notice how much noise that action generates on its own).

    Provided that a subsonic load is used (so the "sonic boom" is eliminated) and the mechanical noise is within limits, the only area of work toward sound suppression is the muzzle blast. The first truly successful sound suppressor for weapons was patented by Dr. Hiram Maxim in March 1908. The single formula from Physics known as the "General gas Law" stated that pressure equals temperature multiplied by a constant divided by volume.

    By the muzzle blast being a result of highly pressured and extremely hot gases exiting the barrel, reduction of this pressure before exit by increasing the volume and decreasing the temperature, reduces the sound. It goes without saying that the bigger the volume (suppressor chamber) and cooling of the gases, the more successful the sound suppression is.

GLOCK 19 , cal. 9x19, with “LION” carbon fiber suppressor

    For obvious practical reasons, modern "dry" sound suppressors are designed to incorporate other factors to aid to the desired results and smallest size without having to resort to superficial environments (water, oil, other liquids etc.).

GKD Extra Shorty and suppressor combo
Click to see our Extra Shorty with Suppressor combo

    By creating more turbulence inside the suppressor's chambers the exit of the gases is delayed, thusly aiding in the cooling of the gases and drastically reducing their volume, resulting in extreme reduction of the muzzle blast sound.

    Some suppressors are "masking" the sound of the gases by changing their frequency to the portion of the audio spectrum that the human ear is not sensitive. That results on units that sound much less than the sound meters are reading. This method will need to be evaluated by experimentation to see if the new sounds not noticeable to the human ear, are noticeable to animals which will be a problem to the user that wants to eliminate varmints from his land without alerting all the other animals in the surrounding area.

    The decibel (db) scale is used to evaluate sound suppressors. By logarithmic scale, 3 db is a factor of 2, 10 db is a factor of 10, 20 db is a factor of 100 and 30 db is a factor of 1000. This is in sound pressure levels as measured in pressure units (Pascales): Zero (0)db level is 20 microPascales, threshold of human hearing.

Keep also few samples in mind for comparison :

    Low voice conversation is about 50 db, hand clap about 65 db, a jackhammer about 120 db and a .223 cartridge fired in a standard rifle is 165 db. By International Standards 140 db is the limit of the human ear tolerance before damage starts.When you see a suppressor's data and it claims reduction of 100 db means that the suppressor in question reduces the sound of an M16 firing a .223 Rem. cartridge to a sound level equal to a hand clap! Do not buy that suppressor! The manufacturer is either an idiot or a liar and a crook! There is no such reduction possible, unless the size of the suppressor is the size of a 20 gallon water heater!

    Another factor should be the sound "bouncing" on moving or stationary objects. The same sound suppressor that would sound quite loud in a small room will not even be noticed by a person with good hearing 25 feet away outdoors, behind cover and concealment.

    Remember, sound decreases by the square of distance from the source and the sound level drops dramatically.

    Another thing to remember: Regardless to the proliferation of revolvers with suppressors showing up in Hollywood movies, it is not practical to try to suppress a revolver because of the "gap" existing between the cylinder and the "forcing cone" of the barrel. If you succeed to enclose the whole revolver action you might manage to reduce the escape of the hot gases but the whole exercise will be futile, not to mention expensive.

    I want to know where movie makers are hiring technical advisors! Now, a more practical understanding of all the above will help you realize that suppressing a 22-250 would protect your hearing, but the "sonic boom" generated by the bullet breaking the sound barrier downrange (something like a .22LR shot at a good distance) will be enough to "spook" the rest of the coyotes you where intending to eliminate in one session. You chose the 22-250 in the first place because of its "flat" trajectory, consequence of hyper projectile speed and low bullet weight.

    If you reduce the speed of the same cartridge to 1050 feet per second (below the sound speed level) you will have the same performance of a .22LR, including the severe "drop" over 75 yards.

    If you cannot increase the speed, you have to increase the weight of the projectile to achieve the needed "knock down" power through kinetic energy.

    Without going to extremes, a subsonic .308 with a projectile of 200 grains at 1050 feet per second will "drop" your wild pig at 250 yards with the same sound report of a pellet gun.

GKD Extra Shorty and suppressor combo
Click to see our Briefcase Suppressed .308 rifle

    I hope that I have helped you understand few things about sound suppressors. Now, you are ready to contact us and order yours.

"GKD"