Suppressors Interesting logic from Coastal Suppressors

[bm11]

So my local Class 3 guy who did my recent transfer of my SAS TI Arbiter grinds me to buy a Coastal every time I am in. Not really interested in them, but I had some time to kill this morning before work, so I looked around on their website for a bit. I found the following description of their LRT suppressor, and it made me say "WTF?"

<span style="font-style: italic">LRT 7.62 Sound Suppressor

Before the Long Range Tactical (LRT) Sound Suppressor was designed it spent a long time in development. The Coastal Gun designers knew that certain attributes must be attained if they were to produce a high powered rifle suppressor that would compete in and possibly lead the industry. The main reason for this type of suppressor of course was noise reduction and flash suppression. However we believed that the key to making the LRT one of the best high power suppressors on the market was that it would not only be able to maintain the host rifles accuracy but also improve point of impact reliability. <span style="font-weight: bold">Because of the added weight to assist with barrel harmonics</span> and extremely precise baffle designs, we have developed a suppressor that we are proud to call the LRT. Whether the need is urban tactical or long range surgical targets, the LRT is the choice for the professional law enforcement and military alike.</span>

http://coastalgun.com/products/lrt/

Since when is adding a bunch of weight to the end of a precision rifle a good thing?

 

[Chiller]

Re: Interesting logic from Coastal Suppressors

Depends on how the system is modeled (system/control theory). The slow vs. sudden expansion of gas (the driving charge) I suspect is what they are looking at. As opposed to a sudden (impulse) event you have a slow (step) event.

The same amount of energy is released it just becomes a function or time.

 

[RollingThunder51]

Re: Interesting logic from Coastal Suppressors

Impossible to design for without prior knowledge of the host BARREL PROFILE. In other words, up it goes on my suppressor "Wall of Wonders."

Some folks can't or won't work the newest materials. The welding is expensive, the materials costly, the coatings expensive and time consumming.

 

[CS223]

Re: Interesting logic from Coastal Suppressors

First, I'm no expert on the subject.

If you watch some high speed photography of rifles being shot, in some instances you will see the barrel whip a bit. Thus adding some weight to the end can alter & dampen barrel harmonics much like the slip on Limbsaver barrel dampeners are thought to work. And the barrel tuning device on the new Mini-14 and I think the Browning boss??

Have you ever heard the term "ringing the barrel"? Basically it is suggested that a barrel has a resonate frequency much like a tuning fork. As in any natural oscillation, the wave is sinusoidal. Now picture your barrel oscillating in that manner.

In an ideal situation, you would want the muzzle of the barrel to be at the zero crossing point of the sine wave for it's resonate frequency. That's where "ringing a barrel" is thought to enhance accuracy. Basically, a loose fitting metal o-ring of sorts is slipped on the barrel, and the barrel is thumped. The ring will dance around on the barrel from the resonate vibration. Presumable more when it's in the position of the sine wave peak and less when it's in the point of zero crossing. The goal is to find the point, closest the muzzle where the ring vibrates the least and cut the and finish the barrel to that point.

I haven't seen this discussed much in detail and the question that I have is once you cut the barrel, the resonate frequency changes, so how do you know if the null point will remain the same?

Anyway, most suppressor manufactures claim an improvement in accuracy. No doubt some improvement is a result of changing/dampening the barrel harmonics, probably some improvement is gained from the shooter not anticipating the shot and improved follow through as a result of the reduced muzzle blast.

 

[RollingThunder51]

Re: Interesting logic from Coastal Suppressors

One would have to know exactly:

1. The length of the barrel.
2. The weight/profile/rifling of the barrel.
3. The specifications of the round.
4. The nature of the stock (and perhaps the bipod if not free float)
5. Number of anticipated rounds to be fired (heat).

And then, depending on:

1. The length of the barrel.
2. The weight/profile/rifling of the barrel.
3. The specification of the round.
4. The nature of the stock (and perhaps the bipod if not free float)
5. Number of anticiapted rounds fired (heat)

One could begin to build a suppressor that had as a result of:

1. The length of the suppressor.
2. The weight and profile of the suppressor.
3. The manner bywhich the suppressor dealt with gas dwell and purge.

A complete assembly of the host and supressor that might make a difference.

I know of only one way that a suppressor can productively and repeatedly positively effect the barrel harmonics. That can occur with some integrals where the barrel itself is captured by the external envelope and placed under compression when the suppressor is manufactured. That captured barrel system has a much reduced barrel resonance and accuracy is perceptually improved. But that....that is a whole other discussion, as dedicated integrals are static by design and can be "tuned."

Selling any product that has weight that attaches to the very end of a barrel is <span style="font-weight: bold">absolutely</span> going to effect harmonics. Suggesting without all of the above that it is a positive improvement is unsupportable. This is old science, pursued by a number of suppressor manufacturers over decades. In short, not knowing a priori all above requires the barrel end "device" to be tuneable. Threading a can on isn't. THat is not to say that suppressors cannot contribute to accuracy, they most certainly can, just not as suggested by "weight" added to the end of <span style="font-weight: bold">any/every</span> barrel. I will go one step further, there is some evidence that some suppressor designs adversly effect accuracy by heat retention within the barrel. These designs can have a significant impact on accuracy, causing "strings." This is especially the case if the suppressor covers only part of the barrel (the end), and the profile of that part of the barrel is reduced.

http://varmintal.com/amode.htm

http://www.rifle-accuracy.com/harmonics.htm

http://www.shootingsoftware.com/barrel.htm

 

[HPLLC]

Re: Interesting logic from Coastal Suppressors

I would say adding reasonable weight should always help unless the barrel is a pencil barrel.

I once shot a short barrel piston driven carbine that did 8MOA more vertical than horizontal dispersion without a can, and 1.5-3.5MOA with the can. The suppressor seemed to be obviously helping to dampen barrel vibration induced by the piston into the barrel.

The rubber thing people sell to dampen vibration and increase accuracy is a different operating theory in that it dampens vibration half way down the barrel, but the concept has some similarity in that it adversely effects a barrels ability to vibrate. More weight will cause forces creating vibration of the barrel to be less effective.

Obviously this doesn't hold true for all the cans that have fast attach mounting systems allowing some play in the mounted configuration- because these will throw every round slightly different due to very slight changes the eccentricity of the suppressor to barrel bore relationship.

 

[RollingThunder51]

Re: Interesting logic from Coastal Suppressors

No problem with that...reasonable...no pencil barrels. Unless the barrel shoots really well already.

 

[bm11]

Re: Interesting logic from Coastal Suppressors

A lot of good info that I didn't know in this thread!

 

[D_TROS]

Re: Interesting logic from Coastal Suppressors

On barrel harmonics, Check out the book "Rifle Accuracy Facts" by HArold Vaughn I think it is. That guy goes into everything that effects accuracy. Great great read for understanding ur rifle accuracy wise. Almost a must read for anyone serious about accuracy and precision.

As for the add, that is all salsemen mumbo jumbo frilly stuff to get people excited. In right circumstances, it could potentially increase accuracy, but on the other hand, it could "unbalance" the barrel and also hurt accuracy. 2 sides to every coin thing.

just my thoughts...

 

[Zak Smith]

Re: Interesting logic from Coastal Suppressors

Sounds like an excuse from someone who makes heavy cans.

 

[WYK]

Re: Interesting logic from Coastal Suppressors

The last Coastal guts I saw were nearly basic M baffles. With the new 'annular' design, it would appear they have added some holes to the baffles. Although, in itself, 'annular' merely means 'circular'. If this is the case, this is 50+ year old muffler technology. My current stainless steel suppressor weighs 6 ounces less than their chromoly, as well. It also cost me less than $50 more. I can assume their dealer mark-up is better than most.

 

[deersniper]

Re: Interesting logic from Coastal Suppressors

Coastal cans never impressed me. I don't know why anyone would buy them.

-dan

 

[frog5215]

Re: Interesting logic from Coastal Suppressors

Well, if you were going to shoot unjacketed bullets, they take down for cleaning.

 

[zscurlock]

Re: Interesting logic from Coastal Suppressors

They make a good .22 suppressor. Anything other than that you need to workout before you purchase. We bought some .223's and they were ridiculous. I just couldn't believe anybody would want to put that much weight on the end of there M4. (or any gun) The point of impact shift was 8-10 inches, depending on the host weapon.