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Discussion Starter #1
I've been told that a supressor has virtually the same net effect as a muzzle brake when shooting a thunder-cannon like the .338 Lapua, meaning it significantly reduces felt recoil from firing the rifle. Never having fired a rifle that had a suppressor installed on it, I've wondered if this is true? If it is true, is there a reason that you would opt for a brake when you could have a supressor?

Having talkd with people that have studied the effects of a supressor, it appears that a proply fit supressor has NO effect on either muzzle velocity or accuracy, so that does not appear to be a reason to favor one over the other.

Edited becuse my typing is pretty crappy.
 

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Aren't suppressors illegal, in the USA? Don't you have to have a federal liscence to have a suppressor? That's what I always thought. But suppressors are pieces of special metal that soaks up sound. So they would do the same thing as a muzzle brake, but I doubt the same kind of effect as a muzzle brake. But, of course, those are two different pieces of equipment.
 

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Discussion Starter #3
They are legal for personal ownership in Texas, as well as in a number of other states. Yep be afraid. Yes you need a license (you are supposed to anyway). Yes its a huge pain in the butt, worse than getting an FFL (ask Mel about that little adventure).

I'm not sure of the actual technology of how a supressor works (especially if you are talking aobut wet versus dry supressors), other than they redirect themuzzle blast gas into a chamber and pass it through a series of internal ducts somewhat like a like a muffler on a car.
 

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A sound suppressor _will_ decrease the velocity of the bullet, no matter if it's a "proper" fit or not, because, in the end, that is what it is designed to do. The noise level of a shot depends mostly on these factors:

1: Propellant. Both amount, and burn properties. Which leads to...
2: Pressure, which is what actually propels the projectile, giving it a...
3: Velocity.

As the propellant burns, it goes into gaseous form and creates an enormous pressure. That pressure has to go somewhere, and as the bullet starts to move(unless you put it in there too tight for some reason), that becomes the path of least resistance. As the gas continues to expand, it pushes the bullet before it, with very little gas slipping past it inside the barrel, but there's no such thing as a perfect fit where no gas will slip past the bullet. As it leaves the muzzle, the gas will suddenly be free to expand not only forward, but also to the sides. That gives you a loud noise as the air is set into motion. The bullet will also make a noise, but not _that_ much, unless it reaches supersonic speed(340m/s or more). If the bullet travels at 340m/s or more, it breaks the sound barrier, giving you a flat cracking sound.

Now, since the suppressor is designed to reduce the noise level, what does it have to do? Well, it has to let the gas expand prematurely, before it leaves the barrel. Therefore, inside the suppressor, there are many miniature spaces that the gas can expand into. As the pressure behind the projectile suddenly drops, accelleration will drop, possibly going to zero. Some suppressor designs dissipates the pressure so efficiently that you will get a vaccuum behind the projectile just for a millisecond or so. And, as stated before, at long range, the drop in velocity will make the bullet less accurate. Another factor that plays in is that many, if not most, suppressors are not rifled, which also affects accuracy.

And that concludes todays physics class.... :lol:
 

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Discussion Starter #5
Your explanation contradicts the explanation that I've been given regarding how current suppressor technology functions. But, since I don't make them and have not shot them, I think we can leave it at that.

I have, however, sent an inquiry to STW Suppressors to clarify the effect that their current sniper-based .308 equipment has on both muzzel velocity and accuracy. When they respond, I'll post the answer to the velocity and accuracy question here.
 

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Nekekami gave a great explanation. But, to clarify one thing... once the bullet gets to the suppressor, the amount of accelration will decrease or end, but the bullet is already at a given speed, so the suppressor will not really decrease to muzzle velocity, it'll just prevent further acceleration. For example:

If you have a 20" barrel and are getting 2550 fps, and then you attach a 6" long suppressor. You will still get about 2550 fps. It will not go down, but you will NOT get the increase in velocity that you would if the barrel were a 26" standard barrel, which is what Nekekami was saying. Now, if you have a 26" barrel, and you cut it back 6 inches and add a suppressor, you will certainly have a velocity drop. Or, if you have two rifles, one with a 24" barrel and the other with a 24" barrel that is an INTEGRAL suppressor, you will get slower velocities with the integral suppressor.

Hope I didn't make the explanation worse!!

MEL
 

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Mel:

Actually, I did say that acceleration decreased or ceased altogether. However, velocity can indeed decrease too, even though the barrel length sans suppressor is the same, for example due to the vaccuum effect, and since bullets have low weight, and thus little momentum. Lots of energy, yes, but little momentum(And yes, even .50BMG and similar have relatively low momentum).

And yes, integral suppressors are effective, maybe too effective at times.

About proper fit, what it affects is leakage of gas between the barrel and the suppressor, as well as staying almost perfectly parallell with the barrel. Some less well-made suppressors aren't 100% parallell, and will thus alter the course of the projectile.
 

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Discussion Starter #9
My understanding is similar to that which Mel just gave. The suppressor captures the venting exhaust gas after the bullet has left the barrel, so there is no effect on muzzel velocity. Moreover, the hole on the end of the suppressor is larger than the diameter of the bullet (just like a muzzle brake), so nothing touches the bullet as it leaves the suppressor. Therefore nothing adversely affects the accuracy of the bullet. as to how the rifle report is captured and retained as the same time as the initial muzzle blast, you got me, thats why they get the bi$g $$.

Follow-up on Morpheus question - 35 of the 50 states currently allow individual ownership of suppressors.

Like I said I'll report back when STW gets back to me. Another suppressor manufacturer and information source would beSound Technology.
 

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Jeffvn said:
Follow-up on Morpheus question - 35 of the 50 states currently allow individual ownership of suppressors.
Yeah, I was trying to say was it was illegal to have a suppressor if you don't have that federal liscence. But even if I did have the money, that would take along time to get all the paper work wouldnt it?
 

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Ok. My understanding is from physics classes coupled with material from H&K, BR Suppressors and what we've tested ourselves.

For example, we've tested the BR-Tuote T8G3 reflex suppressor on Swedish AK4's, and there was a measurable drop of velocity, around 75m/s, from 850m/s down to around 775m/s, chronographed, and it was repeated over 5 rifles. Same thing when the Swedish Police were trying out AWC external suppressors for the MP5's the NIS have. There was about 35m/s velocity drop, from around 410m/s down to 375/s.
 

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Discussion Starter #12
OUCH!!!! That is a substantial drop in velocity. You are right it would kill accuracy at any kind of long range.

If you can find a copy of the March or April edition of the Special Weapons for Military or Police Magazine, they talk about a suppressed .308 using an 18 inch barrel. They chronographed muzzle velocities with and without the suppressor using M118 175 grain and Black Hills 168 grain Match ammo. The M118 had no velocity drop. The Black Hhills was 1 foot per second slower unsuppressed. I think that must be calibration error, but so the article says.
 

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Muzzle Break all the Way

It's cheaper and more effective from my understanding. I had a nice muzzle break put on my .300, before it nearly tore my shoulder off and after it kicks a little worse than a 12 ga. shot gun. I paid about $200 for this muzzle break and it works great. A suppressor would cost alot more and not to mention a FFL which will should run you about $1000.
 

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Its $200 for the form 4 tax stamp. The paperwork isn't too bad. I'm running through the process right now to get a tac-ops .308 suppressor for the bravo to use for evaluation. Also, this will help answer some questions about velocity, as I'll have access to a chronograph. I personally feel that it matters a lot about the suppressor design as to what, if any, the velocity drop will be.

I've shot several suppressed rifles, .308, .223 and .22LR. But I have never had a chrono handy to verify speeds. There is always a point of impact change because you are adding a big weight on the end of the barrel that will disrupt harmonics. But generally its the same everytime if attached the same everytime.

Nekekami is right about the suppressor fit. Tac-ops is requiring that I send my rifle back for final fit of the suppressor to the rifle to insure its perfect fit.

MEL
 

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Really???

I never knew that the FFLs were that cheap. I know that you probably have to be a legal age to get one, but for $200 it seems like it's definitely worth it. It does give you the ability to own automatic weapons and other things of that nature right?
 

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Discussion Starter #16
The FFL license only gives you the right to sell firearms (its essentially a dealer's license), but not the right to own or sell automatic weapons or suppressors. I think that requires a class III (or something like that) license. The feds are a bit cranky about handing out the FFLs (and make you wait forever to give you one ask Mel), as they do not want people getting the license just to increase their own personal gun collection. I recall something about needing to sell at least one firearm each year to maintain the license. But, I can't recall if there is an annual fee to keep the license.
 

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yeah, its a class 3 for fully automatics and suppresssd weapons
i just wonder how hard it would be to get a class 3
dont think they would issue them to everyone like they do ccw permits here in my state, Conneticut
but i could be wrong
 

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Having a class 3 licsense, ahem, sucks. It like having an ATF agent move in an live with you.

The first firearm suppressor was invented in 1910 by Hiram Maxim. Maxim was also the man responsible for the first true machine gun. While a suppressor may greatly reduce the noise of the shot, the term "silencer" is technically incorrect because there is no way to effectively silence any firearm. The noise of the shot may be dampened or suppressed but there are no silent firearms in existence.

Sound Components of a Shot and how a Suppressor Works:

There are four distinct components that together make up the noise we perceive as a gunshot. In order of loudness, these are:

  • Pressure Wave from rapidly expanding propellant gases
    Sonic Crack of bullet
    Mechanical Action Noise
    Flight Noise

The pressure wave, produced by the rapidly expanding propellant gases is the only noise component that a suppressor can reduce. The suppressor reduces noise by two mechanisms. The first is it slows the release, through expansion and turbulence, of high-pressure propellant gases that we perceive as a "bang". The second is due to Newton's Law of Thermodynamics (Energy can neither be created or destroyed. It can only be converted from one form to another), where some of the kinetic energy of the noise impulse is converted to heat.

The only way to remove the sonic crack of a high velocity bullet is to utilize subsonic ammunition. Some cartridges are inherently subsonic, while most others can be downloaded to a velocity below the speed of sound. Some integral suppressors utilize ported barrels to bleed off propellant gas and thus reduce the velocity of the bullet.

Bullet flight noise is not loud enough to be sensed by the shooter. However, even subsonic bullets can be heard if they pass close by a person. This noise resembles a whooshing or swishing sound as the bullet flies through the air. Flight noise is too quiet to be heard above a sonic crack.

Suppressor Performance:

The most common method of measuring sounds is the Decibel system. Decibels are a logarithmic scale; meaning the values are non-linear. Eg. A change from 100 to 200 dB does not represent a doubling of the noise level. It represents an increase of 1000 times.

Most suppressors for supersonic cartridges can realistically be expected to reduce the noise of firing by 18-32 dB depending on the design. This represents the limit imposed by the noise of the supersonic projectile. As the suppressor reduces the noise of the shot, the sonic crack becomes the dominant sound. In subjective hearing tests, a suppressed, supersonic cartridge will sound approximately as loud as an unsuppressed .22 rimfire rifle or about 139-141 dB. Suppressors for subsonic cartridges may approach 40 dB of sound reduction however; this is the practical limit of sound reduction at this time. Subsonic systems can be as quiet as 115 dB, which is less than the action noise of a Sterling Submachine Gun (open bolt, blow back action). The dominant sound is the bullet striking the target.

Like firearms, different suppressor designs work best in different applications. Size and weight always work against noise reduction. As a result, one must find a balance between the size and weight of a suppressor and the degree of noise reduction desired for the mission. Suppressor designers are constantly trying to strike a balance between size and weight and noise reduction, which is why there are so many different designs available.

Secondary Benefits:

Suppressors make very effective muzzle brakes. A suppressor reduces the recoil of any firearm by about 30% or as much as a muzzle brake. Unlike a conventional muzzle brake, the suppressor will not blow noise back towards the shooter or cause dust and debris to be blown up, giving away the shooter's location.

Suppressors on tactical weapons allow more accurate and faster target engagement due to reduced muzzle jump and reduced flash in low light conditions.

Suppressors on very large caliber rifles (.338 Lapua or .50 BMG) greatly reduce recoil, muzzle flash, noise and blast. They increases the shooter's comfort level considerably over a conventional muzzle brake because the suppressor directs propellant gases forwards, away from the operator, in a very small arc.

The removal of painful muzzle blast can increase marksmanship as a result of a reduction in flinching, as well as increase the speed of follow up shots.

Reduced muzzle blast can allow longer training sessions and more shooting practice. The muzzle blast from large caliber weapons can be so intense that ear defenders and earplugs may not be effective. In this case the suppressor is the best method of protecting the operator's health.

Suppressors practically eliminate muzzle flash so they are appropriate for use in dark conditions or where the atmosphere may contain explosive gases. A bit of tape over the muzzle of the suppressor will stop gases from entering the suppressor.

Once the first shot has been fired, the suppressor is full of burnt propellant gases, thus providing a non-explosive atmosphere inside the tube.

Types of Suppressors:

Suppressors can be divided into two main categories: Integral and Muzzle. Integral suppressors are designed as a permanent part of the firearm. Muzzle cans are designed to be fixed and removed easily and they do not affect the functioning of the firearm. Neither type of suppressor has an advantage in sound reduction. Integral systems are used where barrel porting is required to reduce the velocity of supersonic ammunition. Integral systems do not suffer point of impact changes as a result of the fitting or removal of the suppressor. They also tend to be more compact.

Mounting Systems:

There are many different ways to mount a suppressor. Two-point mounts are the sturdiest and the least likely to result in a misalignment. Mostly it is only integral suppressors that use two point mounts.

Employment and Techniques of Suppressed Firearms:

It is desirable to suppress a gunshot for many reasons. For entry teams, suppressed weapons allow increased command and control, as operators do not have to wear hearing protection. Suppressed weapons allow operators to distinguish between shots fired by one of the team or a perpetrator.

Suppressed shots are also more difficult to pinpoint, giving the operator an advantage over the perpetrator in the confusion of an armed encounter for greater survivability.

Military snipers can expect to be subjected to intense mortar or artillery fire should their location be inadvertently revealed. The suppressor could be the most important piece of "camouflage" used by a sniper team. The suppressor camouflages the rifle shot by almost eliminating muzzle flash and blast that can give away a sniper's location. Proper positioning of the shooter to cause the bullet to pass close by one or more hard objects can add to the enemy's confusion as the muffled shot will be veiled by the sonic crack which will seem to come from multiple locations as a result of it bouncing off hard objects.

Police snipers can also benefit from the use of suppressors to dampen the noise of the shot for public relations. Even experienced shooters view a quiet gunshot as being from a "less powerful" or "less dangerous" firearm. A full power sniper rifle fired in an urban location can attract unwanted public relations problems.

Suppressors and Accuracy:

A properly designed and mounted suppressor should have no negative effect on the accuracy of the firearm. In fact there is some indication that suppressors actually increase accuracy by stripping the high velocity propellant gases from around the bullet. Without the suppressor, the gases push past the bullet, causing it to yaw slightly as it leaves the muzzle. A muzzle-mounted suppressor will change the point of impact of any firearm it is attached to. However with testing this effect can be corrected for by adjusting the sights.

Potential Problems and Hazards Associated with the Use of Suppressors:

One of the biggest hazards comes from improperly mounted suppressors or a suppressor that loosens during use. This can cause the suppressor to lose alignment with the bore, possibly resulting in baffle contact which can tear the suppressor off the firearm or blow it to bits in a catastrophic failure. During use, all suppressors should be checked for proper tightness regularly.

Not all suppressors are designed to survive full-auto fire or even a high volume of semi-auto fire. A high volume of fire through a suppressor not designed for it can cause the suppressor to fail from baffle collapse or extensive baffle damage. It can also destroy the rifle's barrel from excessive heat buildup in as few as 200 rounds.

Minor suppressor hazards include burns from a hot tube as well as propellant gases and unburnt powder blowing out the ejection port of semi-automatic firearms. Operators should take care to wear proper eye protection when using suppressed weapons.
 

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Discussion Starter #19
Thanks for the scoop. Sounds like my rifle guy was not blowing sunshie in my ear after all.
 

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Interesting cut&paste there, however, some things are off. Such as the noise levels. A bullet striking the target will not cause more noise than the muzzle blast.

http://www.lhh.org/noise/decibel.htm

Those noise levels are widely used in physics and medicine classes all over the world, and are all based on measurements.

As the cut&paste mentions, one of the most important things is that it alters the aural signature(frequencies shift, flatten etc), but if you're in a quiet area, even a suppressed shot will be clearly audible, even if you're behind the shooter. Since my back-up weapon is an MP5SD3, I do have quite a lot of experience with that, and we've tested how well it works out in mixed terrain, 20km from the nearest road, in the middle of the night. Background noise was heavy wind rustling trees etc, a river and various animals. Those that were behind me heard the shots from around 400m away, those to the side from almost a km away, and those in the front 60 degree arc heard it almost 2km away. However, in urban terrain, the noise will be heard, but most likely taken as coming from a faulty muffler, or construction work or something else that seems innocent.
 
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