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Interesting suppressors

 
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Old 11-13-2012, 06:26 AM
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Join Date: Dec 2010
Location: South Africa
Posts: 7
Interesting suppressors

Good day everyone.
Hope all is well with you all.
I have been a member of LRH for quite a while but have never really been able to add anything significant as here is South Africa the long range hunting thing isn’t all the popular and very expensive to get into. But I pop in here every now and again to increase my knowledge and learn from the experts that so willingly share all their hard earned experiences and knowledge. All that I have learned will come into play when I finish up my studies and can afford to lay out some $ to get into the long range hunting and shoot world.
But to get to my topic, I now, after so long, have something to share with all you hunters and shooters out there that you might find interesting.
Here is an article written by Bernie Sharp who is the designer and manufacturer of the following suppressors
Hope you find the article as informative and helpful as I did


SUPPRESSORS OR SILENCERS AS WE KNOW THEM


INTRODUCTION

Suppressors for use on a firearm is not a new topic by any means, but the number of such devices which are becoming used by the general shooting populous is growing by the day in these modern times.

While there are many manufacturers of such devices to be found anywhere in the world today, the majority are used by Armed Forces where the ability to reduce the sound of a weapon being discharged is paramount in an effort to conceal the whereabouts of the shooter.

There is a new breed of users of such devices that is coming to the fore in today’s modern era of the firearm fraternity and that is the average Joe Soap everyday businessman or woman who owns a rifle or two and is an avid fan of shooting and hunting.

More and more too are the number of game farmers and outlets that provide hunting facilities to this growing number of hunting clientele who are realising that the game on their facilities is less disturbed during the hunting season by hunters who have opted to use such a device on their rifle.

In consequence, there are a growing number of these hunting facilities that prefer the use of suppressors on their properties by visiting hunters on the one hand, and on the other there are a growing number of rifle owners, especially those who own the larger calibres, who are finding that the use of a suppressor makes the firing of these large calibre rifles a more comfortable experience due to the reduced recoil while at the same time experiencing less damage to their hearing as well as the ears of those in close proximity to them at the time of discharge of the rifle.

It is to this group of people and to those who are intending to use such a device at some stage in the future that I wish to direct this discourse. While I am just another humble dedicated hunter, I have been involved with the shooting fraternity in the RSA for some forty odd years, going through such disciplines as Practical Pistol shooting, Large Bore Bisley shooting and of course hunting when the opportunity and cash flow made it possible.

As an avid fan and an involved member of the sport I have come to realise that while these devices provide many significant advantages to the shottist, there are some drawbacks to using such a device which many rifle owners seem to be blissfully unaware of until their trusty old piece that used to hit a R2.00 coin every shot at 100 meters now begins to begin to spread their shots in a pattern more akin to their favourite 12 Gauge shotgun.

I therefore began to investigate this phenomenon for my personal interest and because I owned a few of these ‘loudenboomer’ rifles myself and had begun to find that a 60 plus year old shoulder seemed to be protesting more and more with the passing of time. On top of this, my local Aviation Medical Practitioner was dressing me down every year at my annual medical because my hearing test was getting closer and closer to the point where I would no longer be able to fly if present trends continued.

Below are my findings and experience which I pass on to those who are interested with the hope that this information will be able to help you to make the correct decision if you are leaning towards the fitting of such a device to your much beloved and trusted ‘firestick’.

NOISE RELATED TO DISCHARGING A RIFLE

There are five major categories of noise generated when discharging a rifle. In order of timing these are:

Action noise required to ignite the round.
Muzzle blast resulting from the discharge of propellant gas from the end of the barrel.
The sonic signature of the projectile in flight (supersonic velocity rounds).
Action noise in some firearm variants as the spent case is discharged and a fresh round reloaded.
The impact noise created as the projectile finds terminal impact.

The two loudest sounds in a gunshot are typically the muzzle blast and the sonic signature.

Paired reports from the same shot may be observed when the listener is first reached by the shock wave generated by the bullet flying past at supersonic speed (or sonic boom), then by the muzzle blast moving at the speed of sound all the way from the muzzle to where the listener is positioned.

Of course the calibre and power of the rifle in question is also an important factor in this noise, the smaller and lower powered calibres making less of a ‘statement’ of presence than their bigger brothers.

At this stage I believe it is important that we look at the advantages of using a suppressor or silencer on a rifle for the hunter. It is no use reading the rest of this discourse if you are not intending or considering the fitting of such a device.

THE ADVANTAGES OF FITTING A SUPRESSOR

There are many advantages in fitting a suppressor to your rifle over and above those related just to sound although this seems to be the main criteria.

Hunters using center fire rifles find that suppressors bring various important benefits that outweigh the extra weight and resulting change in the firearm’s centre of gravity.

Here is a list of the more important ones:

1. The most important advantage of a suppressor is the hearing protection for the shooter as well as his/her companions. There are many hunters who have suffered permanent hearing damage due to someone else firing a high-calibre rifle too closely without a warning.
2. By reducing noise, recoil and muzzle blast a suppressor also enables the shooter to follow through calmly on his/her first shot and fire a further carefully aimed shot without delay if necessary.
3. Wildlife of all kinds is often confused as to the direction of the source of a well suppressed shot and will hesitate before taking flight allowing the hunter to take a second shot if required and thus ensure the downing of his target.
4. Suppressors reduce firing recoil significantly, primarily by diverting and trapping the propellant gas. Propellant gas is generally a fraction of the projectile mass, but it exits the muzzle at multiples of the projectile velocity, and since recoil energy is a function of mass times velocity squared, the elimination of the propellant recoil can be significant. The added weight of the suppressor also contributes to the reduction of the recoil. Furthermore, the pressure against the face of each baffle is higher than the pressure on its reverse side, making each baffle a miniature “pneumatic ram” which pulls the suppressor forward on the weapon thereby contributing to a counter recoil force.
5. A suppressor also cools the hot gasses coming out of the barrel enough so that most of the lead-laced vapour that leaves the barrel condenses inside the suppressor thus reducing the amount of lead that potentially might be inhaled by the shooter and others around him/her.

Now we come to the next important factor.

CALIBRE VERSUS VOLUME

If we are looking at suppressing the sound of the rifle we find that generally speaking equal quality suppressors can quiet the sound or report of a smaller calibre bullet more effectively than a larger calibre bullet.

This is because stripping the exhaust gasses found directly behind the projectile becomes increasingly more of a challenge.

Likewise, cartridges which produce higher pressures and more gasses will also generally be louder than those which produce less pressure and fewer gasses.

TYPES OF SUPPRESSOR

In the main there are three types of suppressor found in the marketplace today and each has its advantages and of course, its disadvantages which will be discussed later on in the document.
  • NORMAL SUPPRESSORS. Here the unit screws on to the end of the barrel and projects forward. This can add anything from 250mm to 400mm to the length of the rifle while weighing anything from 800 grams to 1.5kg.
  • SEMI-REFLEX SUPPRESSORS. Here the unit extends rearwards over the barrel to a certain extent while still extending the rifle length by at least 250mm. They are of similar weight to the Normal type.
  • FULL REFLEX SUPPRESSORS. Here the unit extends rearwards over the barrel almost to the stock creating the biggest rear chamber possible and only extends the rifle length by a maximum of 160mm. If the unit is built in the same fashion as the suppressor I build, then the weight of the unit should not exceed 850 grams.
At this point it is pertinent to look at the factors involved when a cartridge is discharged in a rifle from a chemical and physical point of view.

CHEMICAL AND PHYSICAL ATRIBUTES OF A DISCHARGING CARTRIDGE

When the primer is struck by the firing pin in your rifle and the charge of powder you have loaded is ignited the following scenario takes place in a very short span of time.

Firstly, as the powder burns it changes and produces a volume of extremely hot gas, the temperature of which would make an oxy-acetylene torch compare to the heat of your local gas braai flame.

Most firearm users do not realise that the average rifle barrel only lasts approximately 1.7 seconds. Yes, I say again, only 1.7 seconds; before it is worn to the extent that it will no longer place shot for shot within a minute of angle at 100m.

This is because the heat of the discharge has eroded the chamber area or other portion of the barrel. The time each shot takes to exit the barrel when fired is so short in time that to get to your 1.5 to 1.7 seconds of barrel life might take you anything up to 2500 rounds or more. So please don’t start to panic just yet.

Now the volume of gas produced by your powder charge is a vital and very important aspect of this process.

From data I have managed to find from various sources it would appear that 1gr of nitro cellulose powder can produce approximately 20 cubic inches or 32.7cc of gas on combustion. To interpolate this, then 30gr of your favourite powder produces approximately 9836cc of gas and 60 gr approximately 19672cc of gas on combustion.

In effect this means that those of us who shoot a .308, 30-06 or similar, create about 9 litres of gas and those with bigger calibres produce 20 litres or more of gas on discharging a cartridge. Now we must remember that this gas produced is super-hot (2000įC PLUS) AND MUST GO SOMEWHERE! It is this super-hot gas that produces recoil and of course the noise associated with the discharge of the weapon. It is also this super-hot gas which causes throat erosion in the chamber of the rifle which in turn causes the barrel to wear beyond allowable limits for accuracy.

Now it is time to look at the problems related to the type of suppressor you decide to fit to your rifle, and there are two main problems that spring to the fore should you decide to fit a suppressor. They are:

a. A disturbed firearm balance, and most importantly,
b. Barrel Erosion at the muzzle end.
Looking at disturbed firearm balance, the most obvious culprit would be the Normal type of suppressor where all of the device hangs forward of the barrel. Obviously the Reflex suppressor would be less of a disturbance as a good portion is over the barrel thus reducing the overhang, while the Full Reflex suppressor would cause the minimum of disturbance to the firearm balance.

However, when we begin to talk of barrel erosion at the muzzle end, this is where the outcome of your choice has a vast result on muzzle erosion and should be the most important aspect of which type of suppressor you choose.

Here I need to digress slightly to take you to the scenario of a rectangular basin filled with plain old water. Now I am sure we have all seen at one stage or another that good old demonstration of what happens to the water when one end of the basin is given a good slap. If we can remember the demonstration correctly we will remember that the water in the basin would rise up on the side that was given the good slap, and then take off like a wave towards the other end.

If we can remember what happened next, we should see in our minds how the wave of water hit the other end of the basin and formed another wave which began to travel back towards the side of the initial disturbance.

This is exactly what happens to this volume of gas created upon the discharge of your firearm when it enters a Normal type of suppressor.

Except for that small amount of gas which is directly behind the bullet and follows the bullet through and out of the suppressor, the balance is caught by the baffles and forms a secondary wave which then follows the path of least resistance, which, by the time it starts to move is back towards the chamber of the rifle. Remembering that this gas is super-hot, it is this returning gas that causes excessive and rapid muzzle erosion.

It has been the experience of a number of rifle owners belonging to the ECGMA Hunt Club that the use of a Normal type suppressor has caused the erosion of the muzzle area of their rifles within approximately 1000 to 1200 rounds and deteriorating accuracy. This of course can only be corrected by the re-chambering and shortening of the barrel or the re-barrelling of the rifle at considerable cost. Not a good outcome at all.

The Reflex type of suppressor reduces the above phenomenon to a fair extent, but again, where do you find the space to “park” some 10 to 20 litres of gas until such time as it is safe to let it bleed out of the muzzle end of the suppressor.

THE ADVANTAGES OF THE FULL REFLEX SUPPRESSOR

This is where the Full Reflex Suppressor such as the type that I build for my own rifles comes in to its own.

Firstly, it creates the minimum of disturbance to the balance of the rifle as the majority of the suppressor is behind the muzzle of the firearm. It also only extends the overall length of the weapon by 150mm or so and by a maximum of 200mm on the very big magnum calibre weapons and weighs almost the same as the lightest of normal type suppressors. (In my cases this weight is approximately 850grams.)

However, when it comes to barrel erosion, this is where this type of suppressor excels in minimising this phenomenon.

Due to its extra-large rear chamber which extends back over the barrel the following advantages are achieved:

A large proportion of the produced gas is turned into this rear chamber producing:
1. A vast reduction in observed recoil.
2. An opportunity for this gas to cool down due to contact with the cool surface of the outer suppressor housing.
3. A brief break in the time between the pressurisation of this gas into the rear chamber and the bullet clearing the end of the suppressor causing the largest reduction in pressure at the exit of the suppressor.
4. The turning of direction of this gas from moving towards the chamber end of the barrel towards the exit of the suppressor due to the “basin” effect explained earlier.
5. The significant reduction of noise below that of a similar weighted normal type suppressor due to the reduction in pressure caused by the change of direction in airflow achieved by this design.

This concept has been proven on the ECGMA Shooting Range where a number of different rifles with different suppressors supplied and fitted by different outlets are found on any shooting day side by side at the shooting benches. The results are always the same: the Full Reflex suppressor is beyond all doubt the most effective suppressor every time.

IN CONCLUSION

A decent rifle in today’s world stands you in at an arm and a leg and is not the sort of item that can be replaced at the drop of a hat. Most people only ever own two or three different calibres dependant on what they can shoot and afford.

The fitting of a suppressor seems to be the requirement of the age much like the latest cell-phone or high definition television set.

In the same manner as the fitting of inferior optics to a good rifle creates an inferior tool for the hunter, so can the fitting of an inferior suppressor cause your pride and joy to become that embarrassing piece of hardware which does not seem to be able to hit what you aim at after a relatively short space of shooting time.

And whereas the military and other specialist users of such devices are able to replace such weapons with relative ease when they begin to fade, this is not the case with the man in the street. Consequently it is of vital importance to choose your suppressor type wisely before making the decision to spend your hard-earned money.

In my humble opinion, the Full Reflex suppressor is the only type to fit to your good hunting rifle, not because I happen to make them, but because it just makes good sense, all factors considered.

Below are pictures of my 375 H&H Magnum for illustration purposes.

The picture shows my 375 H&H Mag with suppressor fitted and then without, and below the two profiles is an insert of the portion of the suppressor forward of the end of the barrel showing the length as approximately 155mm.




One of the female shooters belonging to the ECGMA Hunt Club has fired this rifle with factory 300gr ammunition and remarked afterwards that the rifle “kicked much less than my husband’s .303”, while other visitors to our shoots have often ‘decided’ when standing behind the shooting line that I am using a 243 or 270 calibre rifle.

Again, below is my 7mm Rem Mag with the suppressor and without for illustration purposes. My loads for this weapon use a 139gr bullet at an average speed of 3100fps. The weapon with the suppressor fitted handles like a .243 as far as recoil is concerned, and this can be verified by other members of the ECGMA who have fired this weapon on the range.



Both the above rifles with their respective suppressors fitted can be fired without ear protection without causing the shooter or anyone standing next to the shooter to feel any ear discomfort.

I have also physically fired the 7 Rem Mag directly and about 1 metre over the heads of a herd of sheep approximately 30 meters away from me with the owner’s permission to gauge the reaction of the herd. All that happened was that the herd stopped grazing, moved about two metres forward, checked their surroundings for about 15 seconds and then went back to grazing, and I am sure that most people who have been near a rifle of this particular calibre without a suppressor will know full well that it is considered one of the noisiest and unpleasant weapons for both shooter and bystanders.

Should anyone wish to find out any further information regarding this type of suppressor they are most welcome to contact me by email at berniesharp@mweb.co.za

hope it was a good read
F.L.A.S.H
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  #2  
Old 11-13-2012, 09:04 AM
Gold Member
 
Join Date: Feb 2012
Location: Boise, ID
Posts: 697
Re: Interesting suppressors

A good read indeed. Thanks
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  #3  
Old 11-13-2012, 10:05 AM
Platinum Member
 
Join Date: Mar 2008
Location: SW Idaho
Posts: 1,151
Re: Interesting suppressors

Interesting. This concept is being built into airguns which makes them almost silent. Great for stalking skittish critters.

Questions.

What is involved in cleaning the suppressor?

Is the threaded portion at the end of the barrel the only thing holding the suppressor on? Seems like there would need to be something on the back of the suppressor but if it makes contact with the barrel that is potentially a problem for accuracy.

How much recoil does it eliminate compared to a good muzzle brake?

How long do they last before repairs, etc are needed?

What affect on accuracy have you seen?

Scot E.
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  #4  
Old 11-14-2012, 08:13 AM
Junior Member
 
Join Date: Dec 2010
Location: South Africa
Posts: 7
Re: Interesting suppressors

Hi Scot

Unfortunately I donít have all the answers but please feel free to email Bernie, he will be more than willing to answer and of your questions (he is in Botswana at the moment so will reply when he gets back)
What I can tell you is that it takes away a lot of recoil, I shoot a 270gr Hornady bullet at about 2600fps out my 375 Ruger and it has a stout recoil, Bernie shoots the same bullet at max velocity (2700-2800 fps) out his 375 H&H and it doesnít recoil much more than my un-suppressed 243 win.
I cant tell you much about the effect on accuracy as I donít know how the rifles shot before the suppressors but what I can say is that his 375 shoots through the same hole at 100m
Im sorry that I donít have all the answers. I unfortunately cant afford one of these yet, but will be adding one to the Ruger as soon as I can.
Please email Bernie with any question as I do believe that he is manufacturing a top class product that will serve the LR community well.
Hope I have been able to help, even if just a little
F.L.A.S.H
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