|Article sourced from Target Sports
MODERATORS from JMS Arms Co. by Bruce Potts
Gone are the days when
sound moderators or silencers were deemed a clandestine or difficult
accessory to purchase. Indeed nowadays with litigation resulting from
Health & Safety law, silencers are becoming beneficial for many
Sound moderators, silencers or suppressors, call them what you will,
not only reduce the muzzle report but offers other benefits to target
& sporting shooter as
Firstly the muzzle blast generated from firing a rifle is a result of
the combustion gases expanding at extreme velocity & as they exist
the bore the characteristic gun shot is heard, as is the supersonic crack
of the bullet in flight as it passes by. No moderator can reduce the
sonic crack of the bullet but what they can do is "suppress"
those expanding gases by sending them though a labyrinth of baffle or
chambers to cool the gases & thus reduce the noise as they finally
bore. The speed of sound is generally stated as 1050fps or 333m/s but is
largely dependent on atmospheric criteria such as air temperature &
barometric pressure. The obvious benefit to such noise reduction is
most noticeable in that ear defenders may no longer need to be worn
& the lack of disturbance to surrounding community has to be of
huge benefit in this shooting sensitive society we live
in. The super sonic crack of the bullet is still heard &, yes is
indeed still loud but all the guts of the report is suppressed &
the actual residual noise level cannot permeate as far it otherwise
PHOTOS to posted
Moreover a further
advantage is the very beneficial reduction in felt recoil that,
certainly with the smaller calibres as .222, .223 & 6 PPC allows
you to spot your own shots without the rifle's recoil obscuring your
view. With the bigger calibres such as 6.5 x 55, .308, 300 Win Mag
their recoil is cut to the level of the smaller calibre .22 centrefire,
with obvious advantages. In a situation where a large number of shots
have be expended then the lack of fatigue due to recoil reduction from
using a suppressor has to become an advantage. This becomes very
important whilst zeroing a rifle at the range as, more often than not,
the reduced recoil effect can eliminate the killer flinch, caused by
big kicking rifles: it allows the shooter to concentrate on shooting
good groups & not worry about getting pounded on every
shot. In real teams then a sound moderator has to be a good thing, right?
Well in my view, yes. The only disadvantage is the variation on your
FAC to acquire one, although most Constabularies are sympathetic these
days with regard the Health & Safety issues of hearing damage.
This leaves only the additional weight that a moderator adds to the
rifle as a minus but this is where the PES® moderator that I have
been testing, & other other "over the barrel" type comes
Broadly specking moderators can
be split into two main types, muzzle mounted can (single point
mounting) & down the barrel, telescopic style (two-point
Might Mouse (Aluminium, Black) to fit Air Rifles or .22
£29.95 SMCB Small muzzle can (Blued) .22lr up to
£132.00 SMCS Small muzzle can
£137.50 LMCB Large muzzle can
(blued) .22lr up to
£143.00 LMCS Large muzzle can
66 Over the barrel, blued or stainless
£198.00 SOBS Small over barrel
(Stainless) 32mm diameter,
£198.00 SOBB Small over barrel
(Blued) 32mm diameter,
£198.00 LOBB Large over barrel
(Stainless) 38mm diameter,
£198.00 LOBS Large over
barrel (Stainless) 38mm diameter,
£198.00 10/22 Fully
moderated .22 10/22 barrel kit, with suppressor ready to
Muzzle cans are what they say they are, mounted directly to the muzzle
of the barrel via a thread, diameter & pitch determined by the
diameter of the barrel circumference. These offer the simple method of
adding a moderator to a rifle & offer excellent noise reduction
with the only disadvantage of adding extra length & making a long
rifle even more
The two point mounting system that has recently come into vogue,
offers the shooter a much stronger mounting system. The suppressor is
secured via a thread as normal at the muzzle end & being sleeved
nature down & over the barrel, these types of moderators have a
second mounting point at the rear of the suppressor & half way
down the barrel. This gives a high degree of strength to the system,
as well as reducing the overall length from that of the muzzle can, as
the primary expansion chamber is positioned over the barrel itself.
The weight is more evenly distributed towards the rear of the rifle
& the point of the supporting hand on the fore-end; this turns a
heavy moderator into a finer balanced union with the rifle to improve
handling. At the rear section of the moderator is a bush of a
synthetic material machined to fit the outside diameter of the barrel
& thus enables perfect alignment to the bullets exist via the
baffle stack inside. As this type extends back over the barrel, the
rear section of the moderator becomes a massive expansion chamber
which can take one or two forms. Large models have an inner tube
arrangement that vents gases back from the muzzle to be captured &
then redirected though the baffles & out to the atmosphere: the
smaller cans have no inner tube & vents directly to the barrel
& are sealed by twin "O" rings at the rear. Whichever
you choice, the over barrel system of mounting a moderator is
certainly the way forward in terms of sound moderator
Julian Savory is the proprietor of JMS Arms, based at Handcross in
Sussex & has imported the PES® for three years now. These
moderators are sourced from New Zealand & represent one of the
best value, well engineered & innovative moderators on the market
today. The entire moderator field is covered, from the air rifle &
rimfire market up to the small calibre centrefire with the muzzle cans
of both 32mm diameter or 38mm diameter, to suit your own barrel
contour. The range extends to the over the barrel types again in
either 32 or 38mm diameter with or without inner tubes, to suppress up
to 300 Win Mag. There are several new models designed for specific
applications such as the 66 model for .17HMR & .22 rimfire &
the 10.10 for up tp .223 calibre. There is even a .338 Lapua Magnum
model currently being evaluated.
PHOTOS to be posted
Unique with the PES® range is that they are designed, with the
exception of the muzzle cans, to be field stripped. This has the
enormous advantages with maintenance issues. Access to the innards of
the moderator allows the system to be thoroughly cleaned as necessary
but more importantly, after shooting the harmful corrosive gases still
present in the moderator can be vented to avoid damage to the interior
bore. The PES® moderators come in blued or stainless steel, to suit your
rifle. This offers a better match externally, as well as providing the
better corrosion resistant properties for harsh use with the stainless
steel model. Starting with the Mighty Mouse moderator, this is designed for air gun
& .22 rimfire use. It is available in aluminium tube that is
blacked or silver. It is 160mm long & 22mm diameter & is
muzzle mounted design. The internal baffles form a series of springs
& baffles sections that reduce the muzzle blast from a rimfire
using subsonic ammunition to a dull "thud". At only £29.95
this offers excellent value for money, it is very good in noise
reduction, is light at only 84gm yet still remaining fully field
Next in the line-up are the convenient muzzle can designed for
centrefire use but can also double as good rimfire moderators too.
Available in blued or stainless steel they are not strippable but are
available in either 32mm (small) or 38mm (Large) format, again to suit
the style of your rifle; sportier barrel profiles use the 32mm and
heavy target barrels use the 38mm. The 32mm tube diameter is rated up
to .243 whilst the 38mm is rated to 308 calibre, these offer excellent
noise reduction, taming, even maximum loads down to that of the level
of a .22lr high velocity round. These are the simplest to use as they
just screw on or off the barrel & the only maintenance needed is a
quick squirt of WD40 or similar into the innards to keep them
corrosion free. These are excellent moderators but they do increase
the overall length of your rifle by 252mm, which is why the
"telescopic models" may be a better
bet. The smallest of these offered from PES® are the 66 & 10.10 models
that were designed especially for the smaller case capacity rounds
such as the .17HMR (The 66 model) an the .223 family of cases for the
10.10 suppressor. Both are available as blued or stainless steel items
& have a 32mm diameter body. The 66 has a 6 baffle stack & the
10.10 has 10 baffles, designed to offer maximum suppression for the
.17 HMR & .223 family without excessive weight. They both have a
two-point mounting system with a threaded inner collar to fit to your
muzzle whilst the sleeved outer section is supported by the barrel via
two "O" rings. Yes they are man enough for the job; one is
sufficient but PES® fit two just in case. Price is
Staying with the used "over the barrel" design are the
T12 models, so called because of the 12 baffles available again in
either diameter of 32 or 38mm & finished in blued steel or
stainless as desired. Available either with or without the inner tube
section these moderators offer the best noise reduction for fullbore
loads, rated to 300 Win Mag (&.338 LAPUA magnum being evaluated).
Each comprises of a forward section of 12 baffles that are
hydraulically positioned so as to withstand the huge blast that magnum
calibres can inflict on them & then the outer tube is rolled
crimped to retain the primary, large baffle. This act as a deflector
to send the initial blast rearward down the inner tube section that
encapsulates the barrel. With most of the blast travelling rearward
it, in effect, has to move double the 12-inch length of the moderator
before it exits via the baffle stack to the air which means that the
muzzle report is all but stifled. You only really hear the supersonic
crack with little or no carry-over noise. for those worried about the
32mm versions not having an inner tube & venting direct to the
barrel, do not be. This further enhances the air space within the
moderator &, so long as you clean the barrel after use, there
should be no detriment at all. I have been running one on a .17 Rem
Sako for 2 years & there is only a faint mark where the o-ring
seals touches the
barrel. Further advantages of the PES® range of moderators are that you can
design or specify your own length of moderator so that in the case of
the T12 over the barrel the rear section can almost fit almost flush
with the fore-end for aesthetic as well as acoustic
I have used all the moderators in the PES® range & own six in
total, which should tell you how high I regard them. Finally, for all
you 10/22 fans there is a real treat in the form of a fully suppressed
barrel replacement. PES® offers a ported barrel designed either for
target velocity or subsonic use, there is a difference, that has a
threaded blued or stainless steel shroud outer tube that incorporates
a conventional baffle stack forward of the muzzle. When the 10/22 is
fired the gases are vented from the rear section porting allowing
initial cooling of the gases which are filtered through an acoustic
mesh whilst the remaining gases are retarded by the baffles forward of
the muzzle. What you have is the quietest semi automatic rimfire I
have ever tested, all you really hear is the slap, slap of the bolt
recycling the rounds into the chamber. At £200 for barrel &
suppressor it is a
steal. Whatever way you look at it moderators are here to stay & do offer
the shooter real advantages in terms of noise reduction as well as
reduced felt recoil & sighting your own shoots.
Contact Julian on 01-444 400 126 or mobile 07771 962121 for more
details. try the mobile number first as he is usually out shooting
Article sourced from
SHOOTING SPORTS Mag, March 04.
Little or Large?
With the Hornady
17HMR now firmly establish in the UK, most shooters will want to take
advantage of some form of sound moderation to utilise the mighty
Rimfire at it's best.
There are those who think
that the 17HMR, being a supersonic cartridge, would benefit little from
moderation, but this is not the case at all. We only have to look at
the proliferation of fullbores moderators available today to see that
the practical noise reduction available gives to the modern
Given the specification of the 17 HMR, which throws a tiny 17 grain
pill in excess of 2550 fps, it's interesting to note that in terms of
moderators you can go across the board, from pure Rimfire versions to
fullbore types. This would show weather some of the smaller and less
baffled moderators were just as efficient as the large moderators. In
the past I have noted that there is definitely a "sweet
spot" of maximum suppression within the internal air space. In
fact, sometimes a larger model can be more noisy as you start to get
reverberations or echo
Photos to be Posted
I was going
to use two sound meters, but initial testing proved that there were
too many variables in respect to the size, material & construction
of the individual models I am no expert & some will balk at my
testing procedures, but it soon became apparent it's the human ear
that's the best indicator of noise reduction & not the sound
meter. This is something the Editor agrees with me on, as out in the
field we are talking real time performance & if the level of
moderation spooks less game & attracts less attention, then the
Hardware-wise I used an Anschultz 1717, a Ruger 17/17 Laminated &
a UK custom shop CZ 452. To try & eliminate muzzle crack
associated with supersonic bullets, I first used a soft sand backstop,
then repeated the test across a flat & un-obscured field to avoid
rebound or reflected noise. Hopefully, I had all bases
covered... Also whilst testing, the physicial aspects of the various moderators
became very apparent. Some were long/heavier/bulkier than others
&, though acceptable for testing, would become tiresome &
restrictive in many or most practical shooting applications. So you
will have to weigh up noise reduction with the overall performance,
& price for that matter, to make the right choice for
yourself. I tested 10 moderators in all, ranging from .22 Rimfire models to see
if they where up to it, through the 22 Hornet class & right up to
the large centrefires to see if there was an optimum point where noise
reduction peaked. Typically, the section includes both over-barrel
& muzzle mounted types in all shapes & sizes & I was
actually quite surprised at some of the results obtained. Listed in
the chart are the makes & specifications of each model with a
price &, importantly, the order in which the test crew thought the
Generally, all the cans reduced the muzzle blast to some degree &
were of benefit. None could suppress the sonic crack, but all the
"guts" of the noise was removed & it became much less
intrusive. Additionally, although very light recoiling in nature,
muzzle flip was further reduced & any blast/flame was concealed,
which is handy whilst out lamping at
PES® - JMS Arms,
I tested 4 models from the PES® (Julian Savory) range imported
from New Zealand & interestingly, the
quietest was a joint first place between the 32mm diameter over-barrel
model & the more traditional muzzle-mounted can. Nearly all the
blast was suppressed & all you had was the sonic crack, with very
little rolling echo, or reflected
noise. This is interesting because the muzzle-mounted model was just as
effective as the over-barrel design & shows that only a certain
internal air capacity is needed to optimise suppression for a
PHOTO to be POSTED
The disadvantage of
muzzle-mounting is that overall length is increased, which is why most
shooters favour the over-barrel models these days. But if you can live
with the length increase then the price difference between the two
model may influence your decision; the muzzle can is £73 cheaper at
£132. Nearly as good was the PES® 66; specifically designed for the .17 HMR,
it shows a 6- baffle stack instead of the normal 12, usually found on
the PES® range. This is available in stainless steel & although
costing the same as the larger T12, is actually quieter, & in the
tests came second overall. Also, it only weighs 540 grams & uses a
32mm tube diameter & being an over-barrel model distributes the
weight evenly to give far better handling. Prices at £198.
PHOTO to be POSTED
As stated the T12 model is
designed for large calibre full-bores placed fourth. It's still very
good but the with a 38mm tube - as compared to the PES® 66's 32mm
tube - you are not gaining any advantage. This is what I was saying at
the beginning, sometimes the biggest & wider moderators are
actually noisier than some of the smaller models, as there comes a
point where the moderator has suppressed the gases as much as it can -
bigger is not always
better. The final PES® I tested was their Rimfire - dedicated Mighty Mouse;
good with 22 LR's but with the .17HMR it could only manage 9th place
with the Husher One & SAK moderators. However at only £29.95
& 84 gm, it
was very cheap & still took a lot of the muzzle bite out of the
report, so if money was tight then you could do a lot worse than
PES® Muzzle Can
PES® Mighty Mouse
202mm 28mm £29.95
BR.Tuote Reflex, SAK & ASE Ultra - Jackson Rifles, 01644
I next tried a range from Jackson Rifles, who have been importing the
Reflex moderator for some time now as well as the ASE & SAK range.
These cover all calibres, from Rimfire right up the largest
centrefire, & I tested the Reflex T8, Jet-z CQB, ASE-Ultra rimfire
& Magnum models as well as the SAK Rimfire can.The quietest model
from this supplier & 3rd overall in noise reduction was the JET-Z
which was just as well as it costs £315 & although designed for
larger calibres it really stifled the .17HMR report. It too is a
muzzle-mounted design with a 38mm diameter body, weighing 480 gm, but
has the advantage of only being 153mm long so as not to increase the
overall length of the rifle too much. A nice surprise again was the
effectiveness of the ASE Ultra Rimfire, which was the quietest .22LR
rimfire moderator that was tested. It came in 6th overall, the same as
the bigger Wildcat 200, but it only cost £59.95 as opposed £255 for
the Wildcat. A great suppressor that is light at 270 gm & only
162mm long, but be careful if you want to clean it (I would not) as
the baffle stack is in a 45 deg plane & can be fiddle to correctly
Equally good, financially that is, is the SAK; at only £29.95 it came
in joint 9th place with the PES® Mighty Mouse for the same
price & the £127 Husher One. Although not the quietest for money,
it offered noise reduction at a great price & weighs 220gm-
although with a 35mm body diameter it does look a bit bulbous on
PHOTO to be POSTED
The Reflex T8 came in 7th
in the quietness table; it is good but in my view it's overkill for
the .17 HMR cartridge. It gave a distinct ringing on firing
& although it sleeves down the barrel well it to is bulbous
& too heavy looking to be really be practical... better on a
Wildcat & Growler
Moderators - UK Custom Shop, 01527
New to the market are the Wildcat Moderators from the UK Customs
Shop, which offer stainless steel construction & are totally
strippable. Plus there's a dedicated .17 HMR hard-anodized aluminium
model called the
The 200 model, so called due to its 200mm length, is a large
moderator at 720 gm in weight & with a 50mm body diameter. Being
an over-barrel model helps to spread the weight but it does look out of
place on a sporting profile barrel. It was quiet though, coming 6th in
the table & at £255 you are paying for the build quality &
strip-ability. On the flip side the Growler is light at 168 gm &
150mm long & being an over-barrel model, adds little length, &
the 38mm body diameter does not look too
Staker - JLS & Co
A real treat was result for the muzzle-mounted JLS Stalker moderator.
At 278mm long & 400 gm in weight, it utilises a more conventional
one-piece baffle array, but proved really effective. Placing 5th
overall, the report was very nicely suppressed & offers very good
value for money & shows the older design can still work well -
just look at the older Parker & Hale Rimfire model. The only
downside is the length 278mm is all added to the muzzle, although a
shorter version is available. Good honest moderator for it's
Husher - G&JA
Lapwood, 0845 458
The Husher One, which started a revolution with its no-baffle
design, only managed 9th place which was disappointing, but shows
that some moderators work better with more pressure put into them. At
£127, it's £100 more than the PES® Mighty Mouse, which gave the
same noise reduction, but its added virtues are its excellent build
quality & ease of cleaning.
Sako - GMK Ltd, 01489
Last but not least was a pure rimfire can, from Sako. It came last
in the noise reduction stakes but hey it was designed for a completely
different cartridge! However, it still reduced the muzzle blast
downrange, made the signature far less obvious, & at £25, it's a
budget option. And this can be said of other dedicated Rimfire units
Their true effect can only
be ascertained at the target end & will vary given the
terrain/surrounding you shoot in. Without a doubt all the moderator
tested offered a degree of effective moderation for anyone wanting to
quieten down the .17HMR. Some obviously work better than others &
that is reflected by build but not necessarily the price, as we have
seen. Personally, I favour the PES®, the muzzle can tested the
quietness, priced at £127, weighs 454 gm. Their 66 model, tested in at
2nd quietness, an over-barrel model weighs 540 gm, priced at £198. Both
Article sourced from NZ Guns Issue #59
The quiet approach
Over the past 12 years Mark has developed a range of specialised suppressors which can be adapted to a wide range of firearms, even shotguns. Since 1995 he has concentrated on supplying the trade only.
Back in 1987 Mark Percy began experimenting with sound suppressors (silencers) for his own rifles. His friends soon placed orders and in 1988 Mark produced his first commercial suppressor - a unit designed to quieten down the report from a .22 rimfire rifles. Later, this was followed by a centrefire design which substantially suppresses rifles like the .223, .243 or .308.
|Article sourced from New Zealand GUNS & Hunting, Issue # 61 November/December 2000.
A silenced .44 Magnum Rifle
Mark Percy converts a Lee Enfield.
|While talking to Shane Longney, the Te Puke gunsmith, he suggested that I write an article on my work. A lot of work done by gunsmiths is run of the mill stuff, but occasionally a job comes in that is really interesting.
In my sound suppression business (which began as a hobby) the research and development needed on every new model is intense - successes and failures are all part of the learning process.
I have been manufacturing suppressors for some years now as a part of my general engineering business. After suppressing (silencing) many Marlin Camp Carbines and the odd 45/70 in H&R and Thompson Centre Contender, I wanted something special for myself. Building the rifle described here gave me a lot of satisfaction. I've have only built three of this model to date but all have been sold, so I don't even own one now.
What started me off on this project was an article in the March 1992 issue of the American magazine " Machine Gun News" (yes in the states they have magazines about everything you can think of!) which described the experience of building a run of fifty 45 A.C.P. suppressed Centurion Bolt action rifles. These rifles were manufactured from scratch - later the manufacturer claimed that he would only do another production run if the rifles sold for $5000 each!
The bolt action concept interested me. The Marlin Camp Carbine is an unlocked semi-auto which, even after fitted with a suppressor system, still had three problems for me.
- Noise from the cycling of the semi-auto action.
- Being a keen re-loader, I lost so many brass cases.
- I wanted a bit more power than the 45 A.C.P. cartridges offers.
|Do not get me wrong, if you're not too worried about picking up the brass then the Camp Carbine is really nice to shot. When I test them at the range, without sights, I have no problems at knocking down 8 inch plates at 50 meters.
During the Second World War the British manufactured 45 A.C.P. De Lisle Carbines which were issued to the Commandos. The Carbine was based on the 303 SMLE service rifle, fitted with a .45
calibre barrel and fully suppressed. Over the years I have seen locally manufactured copies which had longer barrel to comply with NZ laws.
I did not go much on the 45/70, but the .44 magnum has been a favourite of mine for years. I had a barrel blank in stock and three junky .303 SMLEs lying about. Both the .303 and the .44 Magnum cartridge have rimmed cases of roughly the same diameter.
After removing the .303 barrel with a pipe wrench I machined the .44
calibre barrel to fit the action. Care is needed in setting the head space. I removed the extractor and used a piece of paper as a crush gauge. Either by machining the rear of the barrel, or the the shoulder in front of the barrel thread, you can obtain the right amount of crush. If you leave the extractor in, it creates a false impression.
The bolt face did not require any work as both cartridges are rimmed as stated, although a little more metal has to be removed from the extractor recess on the barrel to suit the .44 case.
With the barrel in place a .44 cal rifle that would not feed rounds from the magazine, but I planned to cross that bridge later - in the meantime, on with suppressor.
De Lisle and other aftermarket manufactures use a two inch suppressor tube but I have had excellent results with 1 1/2 inch tube. This also allows the fore stock to be channeled out to suit the new tube, while with two inch tube nothing can be done to make it fit. The finished length of the ported barrel is 11 1/2 inches to comply with the 762mm legal minimum length for the rifle. The use of a series of 13 stainless conical baffles completes the inside construction of the suppressor.
What about the magazine? The original .303 magazine had to be used to fill the magazine well. Two days later and my work bench was covered with junk, and even a fabricated box magazine that had been welded into a .303 magazine, but nothing would work.
The project was pushed aside until a farming friend came for annual visit to the city. Being a man of great sagacity, he suggested a .30 cal M1 carbine magazine. Why didn't I think of that? Thirty minutes later and the problem was solved.
The 15 round M1 Magazine holds six of the fatter .44 Magnum rounds,
although for reliable feeding I
|soon found that
three was the best. to feed the rounds from the magazine into
the chamber, the bolt needs to be operated briskly. When you extract the fired cases slowly, they drop in behind the magazine and into the .303 magazine, just like on the original De Lisle. Working the bolt normally throws the empty cases neatly out to land by the shooter's right foot.
Many people wanted to try the finished rifle. One friend borrowed it with reloads that I supplied - a light plinking load that gave great accuracy in my .44 Mag Ruger Super Blackhawk revolver. It consisted of Lyman 240 grain cast projectile with 6.5 grains of Winchester 231 powder.
He used it over the weekend, hunting rabbits and goats. Goats were instant one shot kills with chest shots at 50 meters.
While on holidays in the South Island I left the silenced .44 with a friend to play around with - he worked up the three following loads:-
240 grain Lyman #429421 bullet/ 6.5 grains of W231 - velocity 835 fps.
240 grain Lyman 3429421 bullet/ 7.4 grains of W231 - velocity 1010 fps.
300 grain Nosler / 17.0 grs. H4227 - velocity 1010 fps.
With the Lyman cast projectile and 7.4 grains of W231, the rifle could shoot a three inch group at 100 meters. The 300 grain Nosler HPs shot a group of 4.6 inches at 100 meters. With the .44 zero in at 50 meters, both loads grouped to the same point of impact at 100 metres, four inches below the point of aim.
Full house 240 grain Winchester factory ammo had the same point of impact as the three sub-sonic reloads. These factory loads would be useful for tricky shots, but with an increase in sound signature.
An after-market sporting butt-stock is a must if you're planning to mount a scope, as a shooter can't get his head into a comfortable position for accurate shooting otherwise.
I don't have a meter to test the sound "signature", but I've lent the .44 to people who have had experience with suppressed firearms and they have given me very positive feedback.
Over the past years Ruger has entered the marketplace with a pair of .44 Magnum rifles. a lever action and a bolt action (and this year a new semi-auto too)
The lever action never seemed to gain popularity with us suppressor manufactures - the screw that holds the action into the stock is 100mm in front of the receiver. When fully suppressed there is a 100mm gap between the receiver and the suppressor tube, looks untidy (see the photo in my Web Site www.suppressor.co.nz)
The Ruger bolt action is one lovely rifle, but there is not enough wood in the fore-stock to channel out to fit a full sized suppressor. A real pity. Looks like we'll have to soldier on with the .303 conversions for a while yet.****
|Article sourced from the English Mag. "GUNMART" January 2002.
Sound of Silence
PES® Sound Moderators.
Please Note- PES® Stands for Percy Engineering Services Ltd, a New Zealand based Company.
Bruce Potts tests these revolutionary new silencers from JMS Arms.
Readers will note that I have somewhat of a soft spot for sound moderators/silencers/suppressors, call them what you will. This is probably because other than a scope, a suppressor fitted to your rifle is the next best accessory you can buy. Why? Well in today's society, the merest hint of gunfire is often followed by a telephone call to the local police from worried citizens - even the depths of the countryside. Not only do sound moderator's work by keeping noise disturbance to a minimum, but there are a host other reasons why you should fit one to your rifle. Before we get on to that, here's a report on the new range of PES suppressor, imported from New Zealand by JMS Arms.
Keeping it Quiet.
I went to see Julian Savory, the proprietor of JMS Arm, in his home nestled in the South Downs in Sussex to try myself a new and very unique moderator which is set to create a stir. Julian comes from a farming background and runs a very successful pest control business dealing with farm contracts, commercial and private jobs. He shoots for a living and has used most of the rifles and moderator combinations on the market. Although pleased with certain types of moderators he wanted one that would encapsulate all the best features and a few revolutionary ones to. He is a plain spoken chap, there isn't time in his busy schedule for waffle or wafflers. Likewise, if an item works and earns him money, it's kept ,if it lets him down, it's trashed. Incidentally, Julian is known as "Silencerman" to his customer as he stocks and will get you any moderator you like.
He decided to source the best moderators he could find and is now the importer for PES suppressors. These come in three main models, all of which are available in a blued finish or stainless steel. These are two conventional screw-on 'can' type - one for small centrefire (.222,.223 etc) and a larger model (for .22-250,.243,.308 etc). The third type of moderator is a large Hi Velocity type that fits over the barrel (like a shroud) with a two point mounting system. What is immediately interesting is the inclusion of a stainless steel option, which, we will find out later is not gimmick.
Little and Large.
The smaller of the conventional screw-on units is 250mm long, with an outside diameter (OD) of 32mm - so not too bulky - and it weighs in at 475 grams. The larger version is the same length, but has an OD of 38mm and a weight of 575 grams. These fir via a screw cut thread at the muzzle, which can be 0.5 inch UNF upwards, your choice.
They are very well engineered with a well polished outer casing (blued model) or satin finish on the stainless steel model. Both types have a rolled over front lip which holds the internal baffle system in place and in effect makes them a sealed unit. At first I thought this would be a problem in cleaning, but in tests the system is - for all intents and purposes -'self cleaning', needing, only a periodic wash in solvent and drying with a blast of compressed air.
In both the conventional screw-on models combusted gases are first interrupted by a primary expansion chamber. Then at the front of the moderator, they pass though a series of baffles, perfectly shaped to delay the gases onward passage to the outside world. This system is nothing new, but after testing nearly all moderators on the market with a sound meter, I have learnt that the baffle design and spacing can make or break the performance of a moderator. This moderator has an excellent baffle system and in on-site test it proved better than all the other cans we had to hand.
The Way to go.
After testing many sound moderator systems, I'm convinced that (for large centrefire rifles) having a moderator that sleeves over the barrel is definitely the way to go, but other similar designs that I've tested can heat up fast after 5 shot or more quick shots. This can cause problems with heat haze 'mirage' in front of your scope. This is not a problem for most shooter, but pest controllers, who may have to take multiple shots in quick succession, have found it unsatisfactory.
The larger 'shroud' type PES® Hi Velocity moderator has a two point mounting system. This slips over the barrel and is attached (internally) via a thread at the muzzle and via a nylon spacer at the rear. The rear end of the moderator sits way back on the barrel - almost touching the forend of the rifle used for testing - whilst 6 inches of the moderator extends in front of the muzzle. This is always going to be better than a single mounting system due to alignment benefits, reduced overall length and reduces stress on the barrel thread. It also looks good and actually feels very well balanced compared to a muzzle only mounted system.
The Hi Velocity moderator is 16 inches long, weighs 850 grams, and has an OD of 38mm, so it's quite a brute. Fit and finish is excellent, especially the stainless steel model. Although quite heavy it is built to last and does not seem to get as hot as other moderators.
The baffle system installed upfront is similar to that found in the conventional PES® moderators and is retained by a rolled crimp, whilst a primary expansion chamber is present just in front of the muzzle and extends right down back over the barrel in the shrouded part of the moderator. The gases do not come in contact with the barrel, as there is an inner sleeve that supports the outer casting and is removable should you require cleaning the system (another plus). This moderator not only looks good, but also cuts down the overall length of the rifle without any sacrifice to performance.
One very important factor is that PES® moderators are available in stainless steel, and they don't cost much more than the conventional blued jobs. The stainless steel model will almost certainly last longer and needs far les maintenance cleaning.
Sound reduction performance was staggering. We tried .223, .22-250, 6mm PPC and .308, all fired at 8 feet into a wooden block. In a this way, the supersonic crack is not heard and a genuine reduction can be assessed without a sound meter, as only the combustion gases are suppressed. All four calibres were very quiet - just a muffled rush of hot gases - and supersonic they were like a .22 mag round with no real 'carry' noise. I was gob-smacked and I am now hiring a sound meter for a revisit to test all the available moderators in a mega test for a future article.
It is important to note that sound moderator is not the only benefit of fitting a moderator to your
rifle, there are many other factors to consider also. There will be far less felt recoil, up to 50% reduction in some cases, which also equates to less muzzle flip, so you target stays in view after the shot. This is very handy in spoting your own shots, especially whilst varminting at distance for crows and rabbits where sight adjustment due to wind might be a problem. Lack of muzzle flash is also important - no loss of night vision whilst out lamping..... my old unmoderatored Tikka used to light up the whole farm yard when she went off! A moderatored gun may actually help you shoot better as with lower recoil and added stability (more weight) flinching on the shot is reduced.
Obviously noise reduction is your primary goal and as a moderator is a grate benefit whilst zeroing, as many rounds are used that could otherwise cause a nuisance to the neighbouring public. It's just as important not to disturb livestock - be it dairy
cows, sheep or horses, otherwise the landowner may not invite you back.
Julian Savory also points out that from his experience as a professional pest controller, which believe me is considerable, there are times when you need to take several shots in quick succession if the need arises, that's a fact of life. A moderator allows Julian to shoot several pests one after the other with the quarry unable to determine the precise location of the shot, in fact often a missed fox at 300yds has come towards the shooter as he hears the bullet strike behind him.
On the downside, you will need another variation on your FAC for a moderator, there will be the cost of threading the barrel, extra weight, and the increase in overall length of the gun )conventional moderators only). In my mind the pros far outweigh the cons, and sound moderators are a valid and in some cases indispensable part of shooting in the UK today.
What did I think of the PES® moderators? Well U walked out of Julian's with a .308 Hi Velocity T12 model and have two more stainless models on order - now that should tell you something, I am finishing an in-depth article on .308 subsonic ammunition for fox control, so expect these PES moderators to feature heavily, and I will go into more detail about the mechanic of noise reduction and the advantages and disadvantages of each type of moderator.
For more information on PES® moderators (and most other brands) call Julian Savory on 01273 864470 or fax on 01273 841397, mobile on 07771
962121 ---- Website.
|Article sourced from the UK Magazine "Shooting Sports" May 02, Page 62.
Shooting Sports Magazine. Workshop.
The Big Suppressor Test.
Bruce Potts is once again cracking on about his favourite subject - silenced rifles, but this time he's bought all together in a Centrefire and .22 Rimfire sound moderator round-up.
Please Note. PES® is a New Zealand based Company.
It would seem that at last full bore moderators are gaining greater acceptance in the UK shooting scene, as more and more people realise the benefits, not only to the user, but also to the non shooting public. The choice of types and styles available on the market today has expanded greatly, and each retains it's own merits, pitfalls and price.
I wanted to test as many different models as I could get hold of, in as controlled and unchanging an environment as possible. I borrowed a BEHA 93411 sound meter to record the results. Each reading was taken five times and the average formulated. At this point I should mention I am not a sound technician and although some baulk at the procedure, all the moderators were tested identically and the emerging results in decibels (dB ) closely reflected the relative levels, audible to each of the three testers. Determining the effect of a sudden very fast sound pressure wave is very difficult, but was advised of the setting to use on the meter in advance to achieve as accurate a set of result as possible.
I have tested full bore moderators before and soon realised that the testing ground, background and impeding environment are of some significance; noise reflections from the ground, obstacles, temperature etc., all playing a part in overall performance. Every full bore bullet will travel supersonic if loaded to normal pressures and will therefore exceed the sound barrier at approximately 333 m/s, depending on climatic conditions. This sonic crack cannot be moderated. However, the burning expanding gasses behind the bullet that cause the "boom" and the rolling echo common to all Centrefire rifles can be. Eliminated or cool the gases and these will no longer be discernible. That's the very basic theory, but if like me you are a sad old Luddite, then purchase the excellent book by Alan C Paulson, "Silencer History and Performance" from Paladin Press, available from The Outdoorsman's Bookshop (01293 772496), as this will expand the theory far better than I could ever hope to.
If the supersonic crack cannot be eliminated, it actually makes testing the moderator's performance quite difficult downrange. This is some type of ground absorb more noise than others - for instance, grass deadens more than concrete. Also, if there are trees along the bullet path (as in stalking) it will create a supersonic crack each time it
passes a tree. So, basically the only way to accurately discern how effective a moderator is in performing its allotted role, is by scything these irrepressible extraneous supersonic sounds from the test.
||The Rifles (Left to right); Tikka.223 s/s &PES T12, s/sSako SSR
Fully suppressed .308 SIG, .308 and Vaimeco Ruger 10/22 fully
suppressed, Sako rimfire with Soundbiter, Dave Tooley
Custom 6mm PPC, Sako 75 6mmPPC.
|Selection of Moderators tested.
When chatting to various moderator manufacturers about the manner in which I proposed to conduct my survey, each suggested that a supersonic full bore rifle should be fired into a soft backstop such as sand or straw etc at close range, i.e. 10 feet. This, they claimed, would prevent a supersonic 'crack' from being generated, and thus only the blast would be audible. Why this is, no one could explain, but in practice it most certainly works. So, we now had a test procedure that would eliminate this crucial disruptive factor, and the action could commence.
So to round up, the testing would involve a number of full bore moderators on a .223 and a 6mm PPC rifle, as well as a a similar set up fro .22 Rimfire rifle. The sound meter was placed 10 feet to the left of the shooter, parallel to the muzzle, to achieve maximum peak performance with no other intervening noise. Each moderator would be tested with a series of 5 - shots and from the results an average could be formulated. It should be noted that the shots were taken from an open barn, to eliminate any wind or ambient noise. It was a very quiet and still environment.
However, it should be noted that the floor was concrete, so a certain degree of reflective noise interference was to be expected. It may not be the pinnacle of scientific testing, but as each moderator was used under the same conditions it would serve as a good indication of comparative performance.
The moderators being tested included both single point and two point mounted systems. The former are those that attach via a thread to the front of the barrel. This is the most common type found in the UK and they work well. The only downside is that they increase the overall length of the gun and are prone to misalignment problems if the threads are not properly cut or if it becomes slightly unscrewed during use. The latter is a new design with the moderator slipping over the barrel and mounts at the muzzle via a thread with a further collet, o -ring or conical joint about 8-10" down the tube. This is a vastly superior method - it is stronger, the overall length of the gun is not significantly increased, and it it becomes unscrewed slightly in use, there will be no great misalignment.
The Vaimeco and Hushers are examples of the former types and the Reflex and PES® the latter. I also had a couple of fully moderated rifles in .308 and .22, i.e. ported and moderated back to the chamber area by barrel sleeves.
Right, enough waffle, what were the result? Well, as always we made some very interesting findings, that stirred up several areas of discussion, as well as the need for further testing. However, on the whole it was as we expected.
||Julian Savory, importer of PES® sound moderators
Test rifles were a Tikka .223 Synthetic Stainless threaded for 1/2" UNF, a 6mm PPC Tooley Custom with 16mm thread, and a .22 Rimfore Sako with a 1/2" UNF thread. There was also a fully suppressed Sako SSR .308 and a Ruger 10/22.
Ammuntion for the .223 was PMC 50 - grain Sierra BlitzKing (3300fps) and for the .22 Rimfire was as stated.
|Shooting into straw at 10 feet eliminates supersonic crack
note the position of the sound meter
Comments on the Table One.
It's important to note that sound is measured in terms of it's frequency and pressure levels. These are measured in decibels or dB for short. The dB scale is logarithmic in nature, which means that when a sound doubles you get a 3dB increase. If a 70dB sound is doubled, it becomes 73dB not 140dB. That is why some of those readings look similar, but when you scrutinise it, there is in fact a marked difference performance.
Starting with the .223 Tikka with no moderator, a reading was taken to establish the un-silenced report with no supersonic crack. At 10 feet it was very loud but only made by the combustion gasses. The reading was 130.6dB.
Next the moderators were screwed on, one by one and five consecutive shots were fired to get an average reading of noise reduction. It was apparent that they all worked very well, though some better than others! Also, while some performed better in the dB reduction department, they had faults elsewhere i.e. in construction.
The quietest moderator tested was the PES® T12 Stainless Steel at 123.8dB. That shaves off nearly 7dB over the un-silenced rifle and, as we know, being logarithmic that means the silenced rifle only produced a quarter of the noise - very impressive. You didn't actually need a sound meter to tell you that - just listening revealed how quiet it was. Hearing protection, in fact, was rendered unnecessary, yet moderator-free, the sounds of the gun really hurt. The PES® T12 S/S is a classic two point init: 400mm long and 38mm in diameter, it uses a stack of baffles in front of the muzzle with a massive dump chamber behind. It's heavy at 850g but is very well made. Oh and it's the only can in S/S and is strippable for easy cleaning.
Next best was the Reflex T8 with a reading of 124.9dB, which for all intents and purposes was the same as the T12
PES®, allowing for instrument variants, but there was a define ring to the signature that I had experienced before. This is because at 300mm long and 50mm wide it has a large capacity with a thin outer shell that heats up quickly. It also has a baffle stack at the front and a large dump chamber behind the muzzle. Its sound reduction was very good, but it cannot be be stripped at the rear for cleaning, in my book, the PES® wins. However, note that at 640g the Reflex is significantly lighter than the T12.
In third place was the PES® Aluminium Silent Stalker which at 125.1dB, still provided a significant reduction next to the un-silenced rifle. Furthermore, it did have the benefit of being a meagre 350g in weight. It was very light and a good all round moderator. In joint fourth were the more conventional single point moderators - the PES small and large can versions - which strangely gave an identical reading of 125.8dB, cutting the noise level by over half. Vaimeco came a very close fifth at 126.1dB and at 280mm length and width of 38mm is quite large but easily stripped for cleaning. The build quality, however, is variable.
In sixth, seventh and eighth place were the Hushers that achieved a halving of the noise in both the .223 and 6mm PPC rifles. Unfortunately though, they didn't prove as effective with some of the other on-muzzle designs. They remain the best made moderators available, however, with little to go wrong, and they're easy to clean too. Gerry Lapwood, the designer of the Hushers, has a super moderator in the pipeline - so stay tuned.
Each moderator tested had its own particular muzzle signature. Although some showed the same readings there was a distinct difference in the noise that reached my human ears. As a comparison, I bought along my fully suppressed Sako SSR rifle, shooting dedicated subsonic (subs) at 1081 fps, using a 180gr bullet. This is designed to shoot subs and at 120.1dB you just had a massive 'whoosh' of air - it was very satisfying and remained fantastically accurate too. Julian Savory had a fully suppressed subsonic 7.62 x 39 which shot 220 grains subs that gave a good 121.9dB reading. At this point it was noted that there was probably some reflection noise coming back off the straw and surroundings...but all the guns were shot under the same conditions so I feel the results are valid.
||PES® T12 stainless steel on Tikka .223 S/S -
an excellent outfit for lamping foxes from vehicles
Test Table one (full Bore).
|| dB Level
PES® T12 S/S, .223
PES® Ali, Silent Stalker, .223
PES® Small Muzzle,. 223
PES® Large Muzzle,.223
Husher 1, .223
Husher 2, 6mm PPC
Husher 2 Plus/Plus, 6mm PPC
No Moderator .223 (subsonic rounds)
Fully Suppressed .308 (subsonic)
Fully suppressed 7.62 x 39 (subsonic rounds)
|Excellent decibel reduction was achieved from both the PES® and Reflex moderators
Comments on Table Two.
The .22 LR moderators were tested at the same time location and under the same conditions, but also outside in the 'free air' to ensure no reflective bullet impact noise could be heard, just to see if the results were the differed.
Ambient background was about 51dB. Using a Sako rimfire with PMC subs unless stated, the results were as follows. Surprise, surprise, the PES® Aluminium Silent Stalker came tops with a 87.6dB reading, cutting the un-silenced 103.6dB by a remarkable 16dB reduction. This is seriously good if you remember the nature of the logarithmic 3 dB doubling scale. The PES® aluminium Silent Stalker is light too at 350g and being a shrouded two point system, it has all those associated benefits. Using Winchester ammo the reading increased to 89.5dB.
The Sako moderator gave a very good account of itself at 93.5dB, with the Parker Hale model close behind at 94.6dB. Of the two, I would choose the Sako as it is the lighter and has a one piece baffle system for ease of cleaning. Next were the Husher 1 and the Sound Biter at 98.5dB and 97.1dB respectively, each still at least halving the decibel reading of the un-silenced gun. Out of interest we shot some Stingers un-silenced at 119.0dB and silenced (PES® Ali Silent Stalker) at 109.3dB- and a highly impressive 10dB reduction with high velocity ammo resulted, nearly bring it down to an un-silenced PMC subsonic level.
The fully suppressed Ruger 10/22 rifle stole the show sounding off a diminutive 86.5dB using PMC ammo. It was clear that this was the limit of sound detection using these methods, as the action noise was as loud as the report! It was decided to shoot the .22 LR outside into free air because, for one, the supersonic crack elimination was not an issue as we were using subsonic .22LR ammo and, also, to see if the reflective noise and bullet impact would make a significant difference to the readings.
|Suppressors certainly have their place in vermin control
Test Table Two (.22 Rimfire).
|| dB level
|| PMC subs
|| " "
|| " "
PES® Ali Silent Stalker
|| Winchester Subs
PES® Ali Silent Stalker
|| PMC subs
PES® Ali Silent Stalker
|22LR no moderator
|| PMC subs
|22LR no moderator
10/22 Fully Suppressed
|| PMC subs
Reflex T8 on Tikka H/B .308
very good decibel reduction
PES® T12 (blued) stripped for
cleaning. The out shroud with
baffles can be removed
|Comments on Table Three.
Still in first place was the PES® Aluminum Silent Stalker at 87.4dB - with no real change to the initial reading of 87.6dB. Second up was the Sako at 89.3dB as with the first test, but at 93.5dB the discernible level had dropped by at lest 3dB, therefore halving the sound again. This was interesting - it actually sounded quieter, so bullet impact or reflective noise was clearly playing a part. Third came the Husher that had improved its reading from 98.5dB to 94.1dB - a significant decrease for the better. This did not surprise me, as the Hushers tested previously against the straw bales seemed to change the frequency of the report and push the noise out of the moderator more directionally, so maybe it suffers worst from reflective noise? The Parker Hale now came in fourth at 96.2dB and the Sound Biter fifth at 98.2dB.
however, all the moderators significantly reduced the noise level and in reality the choice would have to be made on the cost of the individual moderator compared to its effectiveness and functionality. As an after thought I shot an un-silenced pre charged air rifle .22 which gave a loud 98.4dB reading... therefore nearly all the silenced .22LRs were quieter than an airgun.
Test Table Three (.22 Rimfire in open air).
|| Winchester subs
|| " "
|| " "
|| " "
PES® Ali Silent Stalker
|| " "
PCP air rifle no silencer
||Fully moderated 10/22, the quietest test bed
Conclusion - or not!
I don't know about you, but I found the results very interesting, if a little inconclusive - further testing is certainly in order.
Realistically these tests have their limitations, and as stated I am not a sound
technician, but I have found that dB readings are not everything, and if you travel downrange - which is where your target is going to be - the results can vary a lot and perhaps this is a truer test?
Every piece of ground people shoot over is different, people's hearing varies, and inherently inconsistent factors such as temperature, pressure, weather, etc., all play a large part in the overall picture of the noise reduction achieved from moderators. One thing that is for certain is that moderators are here to stay and they provide the shooter and the public with very good noise reduction. To the shooter the benefits also include reduced recoil, being to sight your own shots, no muzzle blast, and no ear muffs for sporting use etc. Their downside is extra cost, extra weight and cleaning, but I think advantages by far outweigh the disadvantages.
At the end of the day, regardless of actual meter results, what you want is a moderator that mutes the signature of the rifle report to a level that, 1. does not alarm neighbours or their livestock, and 2. lessens the chance of alarming quarry animals.
At a point of interest I am writing a piece on fully suppressed rifle for sporting use and subsonic full-bore rifle ammo for the use in vermin control, so stay tuned. SS
- Husher - G & JA Lapwoods (0845 458 3633)
- Parker Hale - John Rotherey (01730 268011)
- PES® - JSM Arms (01273 846470)
- Reflex - Jackson Rifles (01644 470223)
- Sako - GMK (01489 579999)
- Vaimeco - GKM (01489 579999)
- Small Centrefire Stainless - £105
- Large Centrefire - £110
- Large Centrefire Stainless - £115
- T12 (Blued) Hi Velocity over-barrel - £160
- T12 Stainless, Hi Velocity over barrel - £175
- Ali Silent Stalker, over-barrel - £165
- Husher One - £127
- Husher One Plus - £199
- Husher Two - £175
- Husher Two Plus - £259