Airgun Suppressors/Silencers and MuzzleBrakes
Compiled by AirGunEric
First off, a muzzle brake is not a silencer (or muffler, or moderator as silencers are known in different areas of the world).
If a muzzle brake reduced the sound output on a gun, even to a minimal extent; it would be a silencer, not a brake, and
be classfied as such for all legal purposes.
A muzzle brake really only has a few functions:
a) Cosmetics; some people like the look of something other than a plain barrel tube on the end of a gun.
Here's a picture of a readily available muzzle brake- the Beeman 'Universal' Muzzle Brake:
b) Protection- of the barrel/barrel tube itself and the barrel crown from scratches, dents or other damage as a result of
dropping, impact, or rubbing the gun on something.
c) Assisting with muzzle steadiness, partially eliminating muzzle 'wobble' or 'flip' when firing- by adding weight to the end
of the barrel to counteract (even if only slightly- a typical muzzle brake weighs 3-6 ounces) pull up resulting from recoil.
d) Sound re-direction- i.e. ensure all sound coming from the barrel goes forward, or depending on the size
of its expansion chamber (empty space between its walls and those of the gun barrel) and the angle of any vents or holes
in it- in virtually any direction- although this is often pointless as anything but a forwardly directed sound wave and
any accompanying gas escaping from the barrel would be redirected back towards the shooter.
e) Flash reducer: Not applicable to airguns- only for powder-burners.
f) Optional: A more convenient cocking handle when used on a break-barrel gun.
g) Debatable: Improve accuracy of the gun- although this last assertion has not generally been proven in real-world testing.
The theory behind ''improving accuracy'' is that because the pressured gas forcing the projectile out of the
barrel can affect the trajectory of the projectile at the moment it exits the barrel completely- as in push it slightly askew, a
muzzle brake's expansion chamber can contain this uncontrolled gas release at the barrel tip slightly, helping to keep it from
affecting projectile trajectory. However, even just thinking of this- it makes little real sense: Why would having the
escaping gas released into a more contained space; the expansion chamber; HELP projectile trajectory vs. a wide-open,
non-shrouded barrel allowing gas to escape? Seems more likely the projectile would be upset even more by a brake,
not less. Perhaps an extremely well-designed and throughly tested muzzle brake could aid in accuracy, even if only minimally-
but this does not seem to be something done generally with the muzzle brakes available commonly.
Typical installation method/construction of a muzzle brake:
A silencer (or moderator, damper, suppressor, modifier or muffler, etc.) is intended to do exactly what it sounds like- reduce
sound, or ''silence'' the gun when fired.
So- what sounds do come from a gun when fired?
a) The action cycling of the gun- i.e. the firing mechanism. The trigger and hammer of virtually every gun
makes noise when actuated for firing.
b) Target impact- while not really a sound from the gun- it is caused by the use of the gun so that when
the fired projectile comes in contact with something- sound is produced.
c) Sonic crack: This is the sound of a projectile when it reaches the ''speed of sound'' or roughly 761.2 miles per
hour (mph) or 1116.43 feet per second (fps) at sea level in 65*F conditions. When a projectile reaches
this specific velocity (usually on its way to a higher velocity- i.e. on the acceleration curve) a sonic ''boom'' is heard, much like
that of a fighter jet airplane (not nearly as loud as a plane, as the size and power of a gun's projectile is alot less than that of such
an airplane). This sonic ''boom'' or ''crack'' is quite loud- but usually not as disturbing as the last notable gun sound:
d) Muzzle blast: This is caused partially by the hot propellant gases that push the projectile out of the barrel
escaping the barrel end and coming into contact with cooler outside air- i.e. thermal shock, and by the ''uncorking''
effect of the projectile once it leaves the barrel allowing the gases to escape- i.e. rapid pressure change. Muzzle
blast can be very loud and is affected by the volume, and temperature of the escaping gas in comparison to
the temperature of the air outside the gun barrel.
Silencers do not address the sounds produced by action cycling, target impact or sonic crack. Silencers only deal
with muzzle blast. By containing and dissipating the gases exiting the barrel, slowing them down and allowing for a
lower rate of temperature and pressure change- the sound output is reduced. How far reduced is dependant upon the design
characteristics and sizing of the particular silencer. However, even potatos or plastic soda/pop bottles placed
in front of a gun barrel act as silencers- perhaps not the most effective silencers- but silencers nonetheless. Silencers can
also have the same effects as a muzzle brake in respect to cosmetics, barrel protection, muzzle steadying, flash
reduction (not on airguns), cocking aid, and as a [dubious] accuracy improver.
Picture of an SRT Arms .22 caliber 'Cheyenne' suppressor:
It is probably worth addressing the modern histroy of the silencer in order to get a better idea of how relatively
simple it's design and function.
In early 1909 The United States Patent Office granted a patent to Hiram Percy Maxim of Hartford, Conneticut
representing the Maxim Silent Forearms Company of New York, New York for a ''silencing device'' for firearms. This was
not the first ''silencer'' to be patented or manufactured- but earlier silencers were generally oriented strictly to
restraining and containing the escaping powder at the end of a barrel to reduce noise- which was, depending on
a particular device, sometimes effective and sometimes not so much. Some of these earlier ''silencers'' would actually
attempt to block the barrel bore with a flap after the projectile passed through in order to stop the rapid
escape of burnt, and still burning, gunpowder. Needless to say- these devices were the least effective of all and
functioned far better as flash reducers than as silencers.
Maxim's silencing device is considered to be the father of all modern silencer/suppressor designs as his basic
design and the applied scientific principles have changed little, if at all, over the last century. Maxim's device
was designed to redirect the gunpowder and expanding gases exiting the barrel, forcing them through a rotary
''pathway'' in which they could dissipate their energy before exiting through the barrel of the gun itself. To achieve this, his
silencer basically had curved ''wings'' surrounding the barrel opening, much like enclosed spring coils, that
caught the majority of gases and powder escaping the barrel, directed them to an expansion chamber, and then allowing
them to exit after expanding and cooling back through the 'wing' openings and out the silencer's muzzle.
Here is a cut-away picture of the design that was part of the 1909 patent:
f) projectile/projectile path
Note: Picture the baffles surrounding the projectile path fully- in this diagram seven baffles encircle the entire
projectile path and if seen looking at them head-on would appear much like little steel donuts.
Modern mass produced silencers/suppressors carry the same basic design features as that of Maxim- wings or fins
(more modernly referred to as ''baffles'') around the projectile path capturing hot gases and powder, leading them
to an expansion chamber where their energy is converted to heat and then exiting the muzzle in a delayed manner after the
projectile has passed through. The methods of how the gas is redirected vary somewhat, with some silencers using
multiple layers of ''baffles'' leading to multiple expansion chambers which are typically lined or filled with a
sound-reducing media, for example metal mesh or steel wool. Some silencers use multiple ''mazes'' or a series of
baffle pathways to redirect gases on their route to an expansion chamber. This configuration is referred to as a
''stacked baffle'' suppressor. Others use steel, titanium or inconel baffles with rubber or plastic ''wipes'' designed
to touch the projectile as it passes in order to scavenge/redirect as much of the muzzle blast as possible.
Different silencers may have one, or multiple expansion chambers placed either at the front of the silencer, or spread
throughtout. Silencer effectiveness is also influenced by the size of the expansion chamber or chambers- more expansion
space allows for greater sound reduction, i.e. the larger the overall size of a silencer- the more it will tend to suppress sound.
The SRT Arms .22 caliber "Odessa" suppressor:
Essentially, all silencers convert expanding powder and gas energy (velocity and sound) to heat- controlling
both issues that cause muzzle blast sound- the gas expansion rate (rapid pressure change) and hot muzzle gases
meeting much cooler ambient air outside the barrel (thermal shock). This conversion to heat is released within
the silencer itself and can cause silencer casings to get hot enough to burn things they touch (severely) and why ''wet''
or liquid-cooled (water, oil or grease) silencers have been developed which cool somewhat more efficiently than air and also
help reduce muzzle report further due to their denser-than-air sound-dampening characteristics.
Many advanced silencers/suppressors available today are actually ''tuned'' units designed for use on a specific gun
using a specific type of projectile/ammunition. These types of suppressors have been designed for a single configuration
and will not perform as well if used on a different type or model of gun or with a different type/brand of projectile.
Even more advanced units have designs set-up to redirect gases in such a manner that the gases from different
baffles will ''collide'' head-to-head in an attempt to have their wave amplitudes (sound frequency pattern) cancel each
other out and push the remaining frequency pulse (sound) into a range not able to be heard by the human ear, i.e. 22+ kHz.
In respect to airguns- obviously burnt/burning gunpowder is not collected by the silencer- but lead particulates and, if
there is any truth to the ongoing debate about springer-type airguns ''dieselling'' slightly with every shot as it burns
lubricants- perhaps some other residues. As such, silencers- both on firearms and airguns, need to be cleaned
periodically to remove anything built up and blocking the flow of gases through it resulting in reduced efficiency. Something
to keep in mind on airguns with ''built-in'' non-removeable silencers- how will they be cleaned or the baffles inside be
replaced when the time comes?
Because silencers act as an ''open'' barrel attachment- they do help to increase muzzle output power just like a
longer barrel (by giving the gases pushing the projectile forward more time to expand). But, because the projectile
path is not tight or sealed completely like a barrel bore, the increase in power is typically only 3 to 10 per cent. Accuracy
with a modern, well engineered silencer will remain the same as with an open barrel, and as with muzzles,
there is some debate as to whether or not a properly designed silencer will actually aid in accuracy. One thing
that should be noted, however, a poorly designed silencer can decrease accuracy- significantly. In recent years, a
standard issue silencer for United States SOCOM operations was reported to commonly reduce accuracy by as
much as 12'' over 100 yards on assault rifles to which they were attached.
There are many sources for ''improvised'' silencers on the web. The ones I've seen could be labelled ''primitive'' at
best. Some are steel tubes affixed to the end of a gun barrel with multiple small holes drilled through, a surrounding
layer of steel wool and an outside canister to hold it all together. Others oriented at pellet and paintball guns (which generate
much less heat output than a conventional firearm) have been made with an inner plastic tube (ABS or PVC pipe) full of
holes, liners made of foam padding and outer tubes of ABS or PVC. These undoubtedly will reduce sound output somewhat-
but how much and at what loss to gun accuracy?
Here are pictures of a custom-made airgun silencer and a muzzle brake attached to a Rohm Twinmaster:
Picture compliments of Alstone. Silencer constructed by Alstone.
Silencer/Suppressor laws and restrictions:
Please Note: Laws and other restrictions to the purchase, ownership and/or manufacturing of any sort of sound suppressor
for use on any sort of gun differ in each country, and sometimes even across different States, Territories or Provinces
within a single country. Please consult your specific country and regional laws for information. This document is only intended
to be a very basic guideline on the sorts of laws that exist in some areas and is not intended to be used as a definitive
A) Silencer/Suppressor- on an air gun?
Yes, many people desire some level of sound reduction on air guns- most typically on high-powered guns with extreme
muzzle output energy. Of course, many people also would like a suppressor for their lower-output airguns, but this is
a matter of personal preference. The availability and laws governing suppressors in a given region also affect peoples'
attitudes/desires for them. For example, suppressors on even lower-powered airguns are quite common in the UK- where
there are few, if any, laws curtailing their availability and use and a suppressor can be purchased cheaply and easily at any gun
shop. In comparison, Canadian laws states that suppressors are illegal and carry a potential penalty of imprisonment,
so they are virtually nonexistent.
B) Region-Specific Guidelines for Suppressors.
The United States does not, contrary to popular belief, ''ban'' silencers/suppressors. A person cannot
purchase, construct or use one without a Bureau of Alcohol, Tobacco and Firearms permit. Some states, however, do
ban the sale and use of suppressors- even if a permit for one has been issued to an individual by the BATF (California is an
example of this)- so check your local laws before assuming if you obtain a permit you're ''legal.''
Also note: ANY device that could potentially be used to reduce the muzzle report of what is classified as a ''firearm''
requires a BATF permit, where allowed. This means that just because you may construct your own suppressor and attach
it to an airgun (not a firearm) you shouldn't be comfortable in assuming you are in compliance with the law. If the BATF can
construe that it may be removed (even if by cutting/slicing or otherwise damaging or destroying the airgun to which
it is attached) and then used on a regular firearm- it would be illegal. Please note, the BATF has construed the reading
of the regulations this way more than a few times.
A specifically relevant section of the U.S. National Firearms Act (NFA), 1968 that has been clarified by the BATF:
(M30) Are Paintball and/or Airgun Sound Suppressers NFA firearms?
The terms ''firearm silencer'' and ''firearm muffler'' mean any device for silencing, muffling, or diminishing the report of a portable
firearm, including any combination of parts, designed or redesigned, and intended for use in assembling or fabricating a firearm
silencer or firearm muffler, and any part intended only for use in such assembly or fabrication.
Numerous paintball and airgun silencers tested by ATF's Firearms Technology Branch have been determined to be, by nature
of their design and function, firearm silencers. Because silencers are NFA classified weapons, an individual wishing to manufacture
or transfer such a silencer must receive prior approval from ATF and pay the required tax.
If I have any further questions as to the classification of a paintball or airgun silencer, who should I contact?
Please send a written request to ATF's Firearms Technology Branch.
[18 U.S.C. 921(a)(24), 26 U.S.C. 5845(a), 27 CFR 479.11]
In order to legally acquire and/or use any sound suppression device, an application to the BATF must be made. This application
has a $200.00 fee (plus a surtax) that is payable irregardless as to whether or not someone is ultimately approved or not
approved to receive the permit. Visit the BATF for specific details on the application process:
Any silencer/suppressor, as specified under the definitions in section 84(a) of the Criminal Code of Canada, is a
''Prohibited weapon'' in this specific case means ''a device or contrivance designed or intended to muffle or stop the sound or
report of a firearm.'' From a common-sense point-of-view a suppressor by itself is not a ''weapon''- but the Criminal Code
of Canada classifies it as such.
In Canada, any airgun with a velocity over 500fps or more and a muzzle energy over 4.2fpe is classified as a ''firearm.'' So- you
may be thinking ''my airgun is not classified as a firearm because it has a velocity or output below XXX, therefore a silencer
wouldn't be considered a prohibited device''. Unfortunately, this would, in practice anyways, not work- it is the device
itself that is prohibited. Although a specific suppressor may be installed on an unregulated ''low power'' air gun not a ''firearm,''
Canadian law enforcement has taken the position that if it's designed to work on an airgun, it will work on a firearm (i.e. a
more powerful airgun that is classified as a ''firearm'').
Anyone found in possession of a defined ''prohibited weapon'' can be imprisoned for up to 5 years.
More information on airguns and suppressors can be found on the Canadian Firearms Centre website:
Europe/The United Kingdom:
For all intents and purposes, the United Kingdom and most of western Europe have no laws or restrictions on the use and
ownership of suppressors. Laws are typically focussed on firearms themselves- not accessories that could be attached
to them, or airguns. In the UK for example, anyone who is at least 17 years old can go into a gun shop, buy a suppressor
and use it- all completely legal and above-board. Most of western Europe is similar in this respect- but consult your
country's specific laws.
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