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
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"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
UNDERSTANDING SOUND SUPPRESSORS
When a firearm fires, creates a sound that is a combination of 3
elemental components :
- 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
- 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.
- 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".
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 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.
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
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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.
(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
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
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I hope that I have helped you understand few things about sound
suppressors. Now, you are ready to contact us and order yours.