Suppressors - How Much Do We Really Know About Them?
|
The ASE range of suppressors is favoured by rifle maker Fabian Connolly for their durability and compactness
|
Most people own one or more of them and those
who have paid serious money for their devices generally assume they have the
ultimate in suppression and that they know everything that needs to be known
about suppression. This is nonsense. I have discovered through hundreds of interviews
and hundreds of hours spent in experimentation that very few people indeed know
anything about suppression. The reason
is simple enough. The people who write
about suppression and more especially the “rocket scientists” who show off
their toys on you tube know very little about the science of sound and the
people who have done serious research are keeping the trade secrets to
themselves. How many times have I
listened to some self-styled expert sound off about the merits of one
suppressor over another who doesn’t understand the basics of sound
transmission? If I were to be brutally
honest I would have to admit that despite reading everything I can find about
this particular branch of ballistics and years of experimentation with various
bullets, loads and suppressor designs I have come to the conclusion that even
well-informed people are guessing. I
have consulted otherwise knowledgeable engineers who simply do not know exactly
why one design is effective and another isn’t.
As I said there are people who really do know the science of sound and
sound suppression but they have gained this knowledge through research and
experimentation and are backed by large budgets provided by, in some cases, the
military and in others by military industries and every development has come at
considerable expense – far more than the ordinary backyard experimenter can
afford. Furthermore they can call on
fully equipped workshops equipped with the latest in machining equipment to turn
their ideas into prototypes which are then tested using even more sophisticated
equipment. When a manufacturer puts a
new design for a 30 calibre rifle suppressor on the market at £1,000 a pop he
has already laid out considerable funds on research, development and tooling
and expects to recover his investment and show profits and is unlikely to
discuss his research in some shooting magazine.
The gun journalist who does a few test fires and promotes the new
product is writing for the consumer not the developer. People like myself who have an interest in
this topic all agree on one point – there is a LOT we don’t know and even more
we are not being told. I know several
people who have built and sold suppressors commercially and even these, while
they may understand their particular product intimately, have more questions
than answers about the wider field of ballistic sound suppression.
|
This remarkable snapshot was taken using a
suppressor with a transparent tube. It
shows the bullet departing the muzzle followed by a blast of hot, glowing gas
that has become trapped in the expansion chambers and is making its way towards
the baffles. The bullet will have
reached the target while the gases are still swirling around inside the suppressor
before emerging cooled and slowed. The
suppressor is doing exactly what it should
|
Suppressors
are referred to colloquially as “Cans” and “Silencers”. The terms “Moderator” and “Suppressor” are
more precise and mean the same thing – a device fitted to a firearm to reduce
its sound signature. The decibel scale used
to measure sound is logarithmic. Gun
shots are not composed of a single frequency but produce a wide band of
frequencies in a characteristic mix that the human brain soon learns to associate
with the discharge of a firearm. A
suppressor can deceive the brain and the suppressor that is especially good at
eliminating higher frequencies will seem quieter than one that eliminated lower
frequencies. The threshold of human
hearing is zero decibels. A quiet
conversation is 56 decibels. A BB gun is
101 db. A standard velocity 22 rifle is
137 db. Hearing damage begins at 140
db. The pain threshold is 141 db. A heckler & Koch MP5 is 157 db. A .45 pistol is 162 db. An M16 is 165db. A howitzer is 183db and death to an observer
occurs at 220db. The first commercial
suppressor was patented in 1909 by Hiram Maxim of machine gun fame and
resembled many of the baffle-stack silencers available today for .22 rifles.
|
A Vaime 22 suppressor. The infamous "Hush Puppy" used to kill guard dogs in Viet Nam. It used wipes to contain propellant gases. The Reflex design, arguably the most successful for cost effectiveness, and Hiram Maxim's patent of 1909 which has never gone away and is much copied and was commercially successful in its day |
What
do we know? The current state of
knowledge among ordinary shooters can easily enough be summarised as follows:
1.
Subsonic projectiles are quieter than supersonics which create a
supersonic crack.
2.
Subsonic (.22) suppressors are more efficient than supersonic suppressors.
3.
Some designs are more effective than others
People
who have read a little more will know that:
4.
Suppressors trap, cool, slow down and then release
propellant gases.
5.
.22 calibre firearms can be suppressed to the point where they can be called
“silent”
6.
Automatic and semi automatic firearms are more difficult to suppress
|
This photo of a black powder hunting rifle taken at dusk gives some idea of what a suppressor has to cope with. |
Tell
a knowledgeable shooter that a suppressed .22 calibre subsonic bullet from a
locked breech rifle is silent while a suppressed .45 calibre subsonic from a
locked breech rifle is not silent and he will probably start talking about
something he has seen on line about a De-Lisle .45 ACP silenced carbine. The truth is that the number of people who
have used a De-Lisle .45 ACP silenced
carbine is very, very small and reliable empirical data is just not
available. Everyone knows how the
De-Lisle works but nobody has seen one working and nobody has used one. The last time a WWII De-Lisle was seen in
public was in the hands of an SAS squaddie in Northern Ireland thirty years ago
and since it has not been seen since one can only assume it is no longer
considered state-of-the-art-must-have military hardware. Respected writers like Ian V. Hogg talk
knowledgeably about it but I suspect Ian has never fired one either.
|
The British WW2 .45 ACP De Lisle silent Carbine was reputedly a successful design and is manufactured today by Valkyrie. It used standard military supersonic ACP ammunition and a ported barrel to divert gases into a shroud suppressor after which both gases and bullet emerged at subsonic velocities. The ported barrel is not in favour today and suppressors are generally used with subsonic ammunition |
Go
on line and look up our transatlantic brethren who seem to get away with stuff
that would land the rest of us in some dingy police cell with our firearms
seized and a beefy representative of the law of the land asking penetrating
technical questions about our activities.
These people seem to have some very interesting suppressed firearms
indeed; from suppressed centre fire pistols to suppressed vintage Sten Guns to
custom-built locked breech heavily suppressed rifles firing subsonic large
calibre bullets. To be truthful it’s all
a bit suspect and one wonders how much of the suppression on display is
ballistic and how much is electronic. In
other words real sound waves undergo modification every time they are processed
by microphones, speakers, filters, Bluetooth, wifi, mp3 compression and so
on. The guy with the nearly silent 9mm
machine gun on YouTube may not be as unobtrusive as he sounds and the Hollywood
myth of the 9mm pistol that goes “PHUT” is just that – a myth. My .22 Anschutz heavy-barrel locked breech
varmint rifle with its A-Tec suppressor goes “PHUT” and as far as I can
determine ballistic suppression just gets louder after that. Explaining this self-evident fact is more
difficult than you’d think. I should
also mention that the “PHUT” is considerably louder at the enclosed 22 range
than it is out on the side of a hill shooting rabbits.
|
The parts of the T8 reflex suppressor for centrefire rifles. The design is tried and tested - an expansion chamber that extends backwards around the barrel and baffles. It is made of stamped, welded steel but corrosion sets in with use and eventually renders it unusable. Aluminium and stainless steel have more resistance to corrosion |
|
This Swedish Mauser Carl Gustav rifle of 1904 was rebuilt by Fabian Connolly in .45 Colt and fitted with a large .45 suppressor. It has been used to research suppression and subsonic ammunition |
A
number of years ago I produced an outline design for my dream gun which I took
to a rifle-builder and received a few months later a beautiful customised
single shot 1904 Carl Gustav Swedish Mauser in .45 long Colt with a .45 calibre suppressor and
mounted with an exquisite 40 year old Pecar variable scope AND a set of Elit
Edstrom Swiss target dioptre sights which I licenced and have used as a range
rifle ever since. It’s not everybody’s
cup of tea and most people don’t appreciate what it is since it doesn’t fall
easily into any of the usual categories.
It’s not as powerful as a rifle calibre nor as accurate as a target rifle
nor as long range as a varmint rifle nor as silent as a 22 nor as fast-firing as
any of a dozen hunting guns but it opened up for me the arcane world of
ballistic suppression. The range of cast
bullet weights available in .451 runs from the little stubby 165 grain round
nose through the Keith 250-325 grain Keith semi-wadcutters to the large 400
grain Casull and the velocity range is from 500 feet per second to 1500
fps. The powders available that can be
used go from the fastest Bullseye pistol powder through Slow pistol powders
like Clays Universal through Lil’Gun shotgun powder to fast rifle powders like
Vectan SP3. I addition I can, if I wish,
legally use Black Powder in it since that is what the .45 Long Colt was
originally designed for. It can be used
with any suppressor having an M18 thread and a .46 bore and I have had a lot of
fun with it and have learned a lot from it and have blown quite a number of suppression
myths out of the water with it. It
doesn’t fill the freezer with venison or rabbit meat or win F-Class competitions
but it taught me what I know (and what I don’t know) about reloading and
suppression. I can never sell it because
no-one would want it and it is the single firearm in my gun cabinet that I can
pick up any time and use to challenge another common ballistic myth or address
a tricky suppression conundrum. After
six years It has, as expected, produced some answers and a huge number of
questions and the journey of exploration continues. I sometimes call it my “bullshit suppressor”
because of the number of misconceptions it has exposed.
|
(1) The massive A20 fullbore suppressor in aluminium and steel from The Whole Shooting Match (2) The little Brocock synthetic suppressor – only two parts and surprisingly effective on air-rifles and .22 rimfires. (3) The Parker-Hale Rimfire suppressor of thirty years ago – still a good design with 11 baffles. (4) the most attractive of them all – the simple SAK rimfire suppressor in aluminium with three parts. (5 and 6 ) the ASE Ultra with double wall construction and 18 baffles. Complex, a little heavy, hard to clean, not cheap but the most effective of the lot. |
When
you own a suppressed .45 rifle the first thing you learn is that your 22 is
silent and everything else is just suppressed.
There is only one silenced firearm – the 22. A subsonic 22 bullet is about 40 grains in
weight with about 2 grains of powder behind it and the small explosion of gas
it produces can be suppressed by just about any container fitted on the end of
the barrel The most silent 22 is a
locked breech rifle with a long, heavy barrel rifle with any good quality
suppressor. The least silent 22 is a
semi-automatic with a short, light barrel, (lots of muzzle blast) and a cheap suppressor on the end. Needless to repeat is the fact that subsonic
22’s are quieter than supersonic 22’s and the supersonic 22 hv, 22 Magnum,
Hornet, 223 etc cannot be made silent. It’s not that a .45 bullet cannot be
tamed – it can but it is never silent.
The 40 grain 22 subsonic bullet produces about 40 forty foot pounds of
kinetic energy. A 165 grain .45 bullet
at 875 feet per second with five grains of pistol powder produces about 100
foot pounds of Kinetic energy - which is not exactly powerful – and a much
louder explosion that even a large, efficient suppressor struggles to
contain. Now here’s the interesting
bit. Put the same bullet weight and the
same load of 5 grains of pistol powder and the same suppressor on a .308 and
the result is much quieter. We can’t put
4 grains of powder and a 165 grain bullet in a 22 but using what we’ve got we
can see that the 22 is the quietest of the three, the 308 is a bit louder and
the 45 is the loudest. A friend of mine
calls this “Ward’s First law of Suppression – Big Bore- Big Bang” and I defy
anybody to disprove it. I’ll repeat
that: all other things being equal, ie bullet weight, powder weight, velocity
and kinetic energy; a large calibre bullet produces a louder bang than a small
calibre bullet of the same weight. I’d
like to be able to say I will now proceed to give a theoretical explanation as
to why this should be – but I can’t.
I’ve consulted engineers and their explanation is logical. The larger circumference area of a 45 bullet
expressed as pi(R*R) produces
a larger gap for gas to escape through than the smaller circumference area of a
22 bullet expressed as pi(R2*R2). Big gap Big Bang. Very good.
Let’s test that. Put a 45 bore
can on a .22 or a .308 rifle and there is no appreciable increase in audible
noise which the theory tells us there should be. You will note I do not refer to decibel meter
test results here; the reason is I found them meaningless. A decibel meter does not measure what the
human ear hears and in the case of a 22 a decibel meter rated the closing of
the bolt and the ping of the firing pin louder than the suppressed shot – logical
for a decibel meter but nonsense for the human ear and brain. Here the engineer and the experimenter simply
disagree and I defy any engineer to prove “Ward’s First law of Suppression –
Big Bore- Big Bang” by recourse to the Engineer’s “Big Gap – Big Bang
explanation. At the time of writing this
is a ballistic dead end until one of those shadowy military ballistics types
breaks the official secrets act to come out of his comfortable retirement to
prove me wrong. A
Corollary of “Ward’s First law of Suppression – Big Bore- Big Bang” is “Heavier
Bullet – Bigger Bang”. Essentially this
means that a subsonic 400 grain .45 bullet produces a bigger bang than a 160
grain .45 bullet. The reason is that
much more powder is required to produce the same velocity in a heavier bullet
and this logically produces more pressure and a bigger bang. This very obvious piece of ballistic fact has
been demonstrated many times and is beyond question.
|
Baffled? Flat baffles seem to work. Add different baffles, wipes or funnel shaped baffles and there may be an increase in efficiency. The permutations and combinations of baffles, bullet types, velocities and calibres are mind-bending |
Ward’s
Second Law of suppression states; “Some suppressor designs are more efficient
than others”. This may seem a bit
obvious to Google experts but it needs stating.
Take two suppressors with two different baffle stacks. A suppressor generally consists of an
expansion chamber followed by a baffle stack that first allows gas to expand
and cool and then confines it to prevent it escaping the muzzle at supersonic
speed. The first suppressor uses flat
baffles and the second funnel-shaped ones.
The first simply blocks propellant gas while the second will “strip”
propellant gas from around the projectile and direct it backwards thus slowing
the rate and temperature of escape. It
is in the area of baffle design that the serious researchers surge ahead of the
pack. A suppressor fitted with more
efficient funnel-shaped “gas stripper” baffles will generally outperform others
although the audible difference will be less noticeable in 22 than in 45
calibre. It is in the area of baffle
design that the perfect match of baffle configuration to bullet shape, diameter
and velocity shows its advantages. I
would speculate that this type of research is also expensive as it necessitates
a lot of trial-and-error and shuttling between a CNC lathe and an experimental
firing range equipped with sound monitoring technology. An idea might produce a baffle design with a
particular angle or shape which must then be machined and fitted in a tube
mounted on a gun which must be fired with a variety of powders and bullet types
and the results compared. That kind of
work is time-consuming. When the final
result has been perfected and marketed the developer will want to keep his
research to himself and charge as much as he can get for his product.
|
Suppressed WW2 Sten guns, .30 calibre rifles, wipes, baffle shape - it's all explained in only one serious book that I have found - Alan Poulson's Silencer History and Performance |
Ward’s
Third law of Suppression states: “Fast Powders are quieter than slow
powders”. Here there might be
agreement. Just as the automotive
engineer does not want fuel exploding in his exhaust system so the ballistic
engineer doesn’t want burning propellant coming out the muzzle of his
suppressor. Fast pistol powders are
designed to burn in a short pistol barrel while slower rifle powders may need
22 inches in which to be consumed entirely.
Muzzle blast is unburned powder.
More effective suppression is achieved when powder has been entirely
consumed well before the projectile reaches the suppressor. There are difficulties here. It has been demonstrated that a bullet that
has reached maximum velocity and has begun to slow down within the length of
the bore will not perform as well as one that is propelled by an efficient burn
and acceleration for the entire length of the bore. It may even be there is a conflict between
efficient suppression and accuracy and that effort must be expended in achieving
a balance. I have demonstrated this by
testing fast versus slower powders at 100 yards in my Swedish Mauser .45 Long
Colt Carbine and the advantage lies with the slower powder. Put another way: shotgun powders are more accurate than pistol
powders in a 20 inch .45 barrel.
|
Improvised devices to test whether a suppressed firearm could be further suppressed met with mixed success. Lagging the barrel and suppressor with sound damping material inside a plastic pipe produced a slight increase in suppression efficiency but you wouldn't want to be seen carrying one around a field! |
Ward’s
Fourth Law of Suppression states: “Not all noise comes from the muzzle of a gun
and is therefore more difficult to suppress”.
When 4 grains of pistol powder are ignited in a .45 Long Colt case and a
165 grain .45 bullet launches down the barrel at 500 feet per second, there is
audible noise at the breech of the rifle.
This is difficult to prove although all firearms can, under specific
circumstances, produce blowback of propellant gases where the chamber pressure
has been insufficient to create a seal between a brass case and the chamber
wall. This is dangerous and should be
avoided and is one of the reasons why shooters should wear eye protection. Short of surrounding the breech of a firearm
with sound damping material this noise is difficult to suppress. Further proof of this phenomenon comes from
the firing of guns with breeches that blow back to provide self-loading
functioning and which have long been recognised as more noisy than guns with
breeches that lock closed.
|
Unlike the legions of Google experts the author has actually fired a suppressed sub machine gun - in this case a 9mm CZ Skorpion while the guest of CZ at the Lieberec sports centre in the Czech Republic. The underground range is equipped with sound absorbing material. The Skorpion wasn't as silent as my 45 Mauser and the noise in the range was deafening. Presumably the people ice skating above our heads heard nothing? |
Ward’s
fifth law of suppression is still sort of being tested. It states “Sound damping materials have
minimal effect on the noise of a suppressed shot”. Many ranges have sound proofing or sound
damping materials in the walls which are intended to protect the hearing of
those inside and outside the firing point and indeed they do by absorbing sound
as opposed to bouncing it around. From a
suppression point of view this is ineffective.
I have often noticed that buildings have minimal further effect on the
noise of a shot that has already been suppressed. I am currently waiting for an explanation of
this phenomenon from a sound engineer but in the meantime an electronic
engineer has offered the following explanation.
“When you fire a shot inside a building you resonate the materials in
the walls and ceiling and the building becomes a speaker”. It is an interesting piece of information and
stresses the importance of what I will call “Primary Suppression”. In other words insulated range buildings reduce
the chances of gun fire annoying local residents but a good suppressor probably
does more.
|
Subsonic 165 grain loads from a 30 calibre rifle with a light A-Tec suppressor are quite silent, especially outdoors. They are ideal for range use but, it should be stated, are probably illegal on deer |
Many
considerate shooters voluntarily and legally fit their 30 calibre target rifles
with factory suppressors to minimise hearing damage when using full-house
target loads. But what about subsonic
.30 calibre loads. This was recently and
legally tested by shooting some of the previously mentioned 165 grain subsonic
.30 calibre loads with cast bullets at an open-air range. Several things were immediately obvious; the noise produced was surprisingly low;
accuracy at 100 yards was marginal and disturbance at a distance from the
firing point was almost zero. When the
load and velocities were increased, accuracy improved enormously to the point
where, at 1650 feet per second accuracy almost equalled a target bullet and
noise disturbance when using a suppressor was still quite minimal. When these loads were fired at 300 yards
accuracy was still acceptable. Obviously
a balance can be struck between range, velocity and suppression and full power
loads can in some instances be replaced by reduced loads with success.
|
The most exciting development in recent times is this Wildcat suppressor with a modular multi-calibre design distributed by Ardee Sports. It features shaped baffles and interchangeable calibre modules |
Ward’s
sixth law of suppression states what is by now obvious: “Large calibres can never be suppressed to
.22 levels even when subsonic ammunition is used”. Of course it leaves open the question as to
whether further research into suppressor, baffle, firearms and ammunition
design can produce improvement. It is
possible, especially with custom-built suppressors to incorporate upgrades and
improvements. An excellent example is
the addition of one or more robust and precise funnel-shaped baffles that
improve gas retention. Modern three and
four dimension CNC lathes can execute amazingly complex shapes and are being
used in the suppression industry. The
modern trend is to take levels of suppression already achieved and execute them
in lighter more compact designs. I
sometimes wonder whether suppressors using modern research and design were made
larger and heavier would even greater levels of suppression be achieved. Such research is likely to come from the USA
and Finland where there are already huge
suppression industries. Legislation
makes it difficult to design and produce suppressors in the UK or Ireland. I believe we will see such improvements;
indeed I hope we do as I have 18% hearing loss from a lifetime of unsuppressed
shooting and would wish the like on no-one.
Ward’s
seventh law of Suppression states:
“Suppression and accuracy are in conflict and genius is required to
balance both”
Back
in the Viet-Nam era, we are told, the brave fighters of the Viet Cong whom the
Americans have traditionally portrayed as uncouth savages as they do with
anyone who opposes them, used guard dogs as a simple, cheap and ingenious early
warning system against infiltration by US special forces. The Americans, who wanted to neutralise these
canine guards developed the “Hush Puppy” pistol which was a 9mm, usually
Walther or Beretta Pistol with a suppressor attached. Hence the name “Hush Puppy”. Being American the Military came up with a
complex solution that achieved a reduction from 160 decibels to 132 decibels
and employed fibre “wipes” to retain propellant gases. The wipes, as the name suggests, actually
touched the bullets and while they stripped gases efficiently they had a
working life of only 35 shots before replacement became necessary. They had a detrimental effect on accuracy
that limited their use to extreme close range.
Reports from the time suggest the dominant sound from these suppressors
was the sound of the bullet striking the wipes and the target and that the
actual gunshot was effectively silent.
If this is true then Ward’s seventh law of Suppression is wrong. Is it true?
I think not. Evidence from people
demonstrating modern pistol suppressors online suggests effective suppression
may not have been that great. One can further
imagine the difficulty the maintenance of wipes created for soldiers in
combat. In more recent times the
Israelis took the obvious step of developing and using suppressed firearms using
.22 calibre bullets which are less troublesome.
The energy differential between a .22 versus a 9mm subsonic bullet is
approximately 70 versus 140 foot pounds.
If the shooter is trained to use the “double tap” technique and keeping
in mind the greater .22 reliability then the “Hush Puppy” may have been
over-engineered to say the least. The
final demise of the wipe came in the eighties when US Federal law classified
them as restricted parts of a suppressor requiring extra paperwork for their
procurement and replacement. People
found other means of suppressing their pistols.
|
How much suppression do you require? Out here in the wilds of Donegal there's nobody to hear |
Ward’s
eighth law states: “The effectiveness of
a suppressor depends on its intended use”.
Many years ago an English Hippy with advanced opinions on how the
paddies should behave moved into a squat beside my favourite hunting spot in
east Clare and proceeded to go for the guards every time he heard me fire a
shot. In those pre-commercial poaching
days there were lots of deer and a shot usually meant meat and the guards soon
learned to ignore this nuisance. I had
nothing to gain by advertising my activities to this principled parasite so I
had Fabian Connolly suppress my rifle.
Fabian, who knows a thing or two about rifles, hippies and suppression
recommended a lightweight model as a compromise between noise reduction and
portability. Shortly thereafter I shot a
deer behind the hippy squat and watched the fun. The long-haired friend of the Earth fired up
his minibus and drove at speed into the wood across the road from his squat –
obviously intending to confront the enemy of the Earth (me). I recalled something I’d read about
suppressors written by a Finn: “The suppressor doesn’t conceal the shot but the
location of the shooter”. Connolly had
sold me a 100% effective suppressor. By
the same token I often used my suppressed .22 rifle in the fields behind my
house. This gun is almost completely
silent and yet after a time my friendly neighbour was able to say to me: “I heard the little slap off your rifle this
morning – did you get a rabbit?” He had
learned to identify the much reduced report of a suppressed 22 Anschutz. The human ear isn’t just sensitive – it
LEARNS. For a few years I carried two
types of ammunition when deer hunting; a full powered soft point thirty calibre
load designed to kill humanely out to 250 yards and a second subsonic load for
situations where I wanted to keep my activities as quiet as possible as when
there were walkers in the vicinity. I
never used the subsonic loads and found the suppressed full-power loads
perfectly suited. Rabbit hunting was
quite different and farmers often asked me to shoot rabbits in fields near
houses. For this situation .22 subsonics
were perfect.
|
The ASE range of fullbore suppressors are forged from anodised stainless steel and near indestructible |
As
with all things in life there is a lot of silly talk and bragging about
suppressors and which centrefire rifle model to buy and fit on the greatest rifle ever
made (no one admits to owning a useless or, as in my case, an experimental
rifle). But then choosing a can is a
business requiring some thought. How do
you choose? Firstly there is the muzzle
thread. You don’t just thread the gun
and bung a can on it. Threads vary as do
the size and weight of suppressors. A
slender barrel requires a smaller diameter thread such as perhaps half inch UNF
or BSF. A heavy barrel might require an
M18 thread. Very few people know much
about this kind of thing or they know a little and claim to be gurus. It is best to consult an
engineer/toolmaker/riflesmith. What you
do NOT do is give the gun to handy joe and let him butcher it with an out-of-true
thread. I’ve seen enough of these to
convince me very few people indeed can be trusted to take the time to set up a
lathe to do a suppressor thread accurately and safely. If the suppressor is not true to the axis of
the bore it is a botch. Then there is
the can itself. It should suit the gun
and be specified by the manufacturer for the calibre in question and suited to
use ie hunting or range work. A hunting
can will be lighter and a range suppressor more robust. There is no rule but common sense dictates
that light and tinny will burn out faster than strong and heavy. A
sealed suppressor is difficult to maintain while a strippable design can
be cleaned and rustproofed. A
beautifully machined strippable modular aluminium model will cost a lot more
than a stamped, welded but robust type.
I confess to a degree of confusion myself when it comes to choosing from
the many designs on the market. I own
two cans in particular that I think are right for the job and value for money;
an A-Tech model in 6mm made from heavy forged steel suitable for serious
varminting and another in 7.62mm and light aluminium for deer hunting. In both cases Fabian Connolly helped me
choose and then fitted the suppressor. I
have owned a couple of English models that were less satisfactory. One was a sealed steel model that rusted to
the point of becoming dangerous and another well made modular design just bound
up and can no longer be stripped. The
problem with the second is of my own making because I left it too long without
stripping and oiling but it highlights a problem. I have a friend, an engineer/toolmaker who
courageously flushed a suppressor with ammonia followed by light oil and
managed to clean it pretty thoroughly.
Whether he has created a corrosion problem remains to be seen. Another acquaintance fills his suppressor
with bore solvent and lead shot and gives it a good shaking to remove
residues. Again this method scares me –
what if a stray lead ball got in the way of a bullet?
Perhaps a buyer needs to look into his soul and ask himself: “Am I
prepared to clean the damn thing every time I use it?” Does “Yes” mean modular aluminium and “No”
mean sealed steel? I rest my case
because I simply don’t know. My .45 can
has long had a welded muzzle plug as a result of a single black powder round
fired out of idle curiosity and ever since I have eyed with dismay and
trepidation the rapidly accumulating layers of soot, carbonised unburned powder
and homemade beeswax-lanolin grease that are adhering to the baffles. Connolly tells me to stop worrying and keep
shooting but I can only manage the latter.
Ammonia is becoming hard to find.
So how much does one spend? I
feel I have to offer something to the bamboozled shooter. Generally when you pay more you are paying
for lightness and compactness so if that’s what you want then lay out
£1,000. If you just want suppression
then pay less for a bigger, heavier model that you can strip and clean. If you are an occasional shooter then go
cheap and look after it. If you own a 22
then just get something that you can clean easily – they all work. My .22 Anschutz sports a very complex
Norwegian double walled job made of heavy forged steel and is a horror to clean
– there are 3-piece aluminium jobs for less money that work as well and can be
wiped out with an oily rag. The most
robust suppressor I have used is an ASE Utra which is forged steel, heavy,
sealed and indestructible.
|
The oil filter suppressor. Best not to try it unless you want to damage your gun, your person and your reputation. Besides it is almost certainly illegal. This is a contrived photographic montage not an actual test |
Is
there a final word on suppressors and suppression? The population of this island is increasing
and more city people are moving out into the country to escape overcrowding,
crime, drugs, noise etc etc. Invariably
some of these people lack understanding of things like spreading slurry on
pasture, fox control, shooting ranges, hunting, dogs worrying sheep and country
pursuits in general and will complain stridently when they see evidence of
behaviour that is beyond their experience.
The suppressor is the single most effective means of pacifying these
people by keeping them in ignorance of what they don’t understand. It also protects our hearing and it is a
wonderful invention. Its possession also
requires a licence and this should be kept in mind. It is classified as a firearm and cannot be
bought, sold, transported or manufactured without paperwork. It should be removed from a vehicle when not
in use as its loss is near enough the loss of a firearm with all the trouble
that entails. As a firearm it should be
stored like a gun in a gun cabinet. Making
your own can is illegal in the same way as making a crude gun is illegal and
doing so is a gift to some policeman’s promotional prospects. I know a chap who decided to design and make
an affordable centrefire suppressor. He
manufactured a prototype and foolishly sent it to the relevant authorities with
a cover note saying he wanted to manufacture and market his “invention”. He is out of business and has entered the
crime statistics. I do not know whether
modifying or improving a suppressor at home is illegal. Common sense dictates that great caution is
called for. Light hunting models are
unsuitable for range use where they are likely to overheat and deteriorate from intensive use. Range models should be
robust. They can be dangerous as when
they are fitted loosely or cleaned carelessly resulting in the bullet striking
the suppressor’s internal parts. They
need maintenance. Steel suppressors can
rust and aluminium models can bind up and should be partly disassembled after
each use and reassembled before each use.
Putting a smaller suppressor on a larger calibre gun can be especially
dangerous. When stored they should not
be left on the gun as corrosive substances can leak down the bore. Barrel cleaning patches should never be
allowed to get into the suppressor where they become an obstruction. Reloaders should be cautious when using gas
checks lest they detach in the suppressor.
Cleaning and maintenance should be as per the manufacturers’
instructions and common sense is required when using powerful solvents. It should be kept in mind that a suppressor
designed for a low powered firearm may not withstand the pressures in a high-powered
firearm.
|
This is a photo of a rifle being threaded on a lathe by a skilled operator. There is no other way to do it without risking damage to a valuable firearm. Amateur handymen should be avoided |
|
I would like to see more research reports on the use of coolants in suppressors. My own experience with wet suppressors suggests the reduction is not great |
|
This table of research results from 1966 suggests significant sound reduction has been achieved by the use of suppressors but not to a level we would regard as silent |
These
days the fashion is for “Ten things you need to know about….” I have put together the following ten
questions to point the way towards a more informed understanding of suppression
and to highlight what we DON’T know.
10
QUESTIONS ABOUT SUPPRESSION
01
All other things being equal; why is a suppressed subsonic .22 bullet almost
completely silent and a subsonic .45 bullet not?
02
Why is a 160 grain suppressed subsonic .45 bullet quieter than a 320 grain suppressed subsonic .45 bullet?
03
All other things being equal; why is a suppressed subsonic .30, 9mm or .30
bullet quieter than a suppressed subsonic .45 bullet?
04
Is a .45, .30 or 9mm subsonic bullet impossible to suppress completely to .22
suppressed subsonic levels?
05
All the experts are talking about the importance of baffle design - why do
baffles make so little difference over a straight expansion chamber?
06
All the experts say a tight fit in the suppressor bore is important but why is
a .45 suppressor on a .22, .243 or 6.5 supersonic rifle so effective?
07
All the experts say a baffle MUST be shaped like an inverted funnel - why does
this make so little difference when tried?
08
Where is the noise of a shot coming from - the muzzle or the breech or through
the barrel wall?
09
Why does a suppressed or unsuppressed shot fired inside a container full of
sound damping material sound so loud to an observer standing outside the
container?
10
Why is fast burning powder more suppressible than slow burning powder?
If
you can answer all 10 questions then you are either (a) a ballistic genius or
(b) you haven't a clue how suppression works. I fear I fall into both categories!!
|
An interesting old illustration of the De Lisle Silent Carbine showing a cutaway with exposed baffles |