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Trial and error...

These rubber donuts are placed along the length of the barrel where they do the most good. How do you know where that is? Simple: You have to put it at the halfway point, and shoot a group. Shoot the very best group you can because if you fly one out there, that throws off the results. You have to shoot close and tight, then move the thing one inch in either direction. Shoot a super-fabulous group again, and see the difference-- if there is any. There should be because the donut dampens the vibrations of the barrel.

You're trying to shoot really good groups so your results are consistent when you move the donut. If a one-inch move blows the group up, try a half-inch move. This is the trial-and-error of the exercise. The idea is to find the location along the length of the barrel that gives the best groups. You'll need lots and lots of tediously-loaded ammo so you're shooting the same load over and over as you move the donut.

If your barrel is matte stainless, use a Sharpie pen to mark the initial location of the donut. You'll need to know from where you started if you want to know at where you'll stop. If your barrel is blue steel, you can use a drop of white nail polish to mark your starting point. You could use a wrap or a small piece of masking tape for either type of steel if putting something on your barrel is not a cool idea for you.

Shoot a group, assess it, allow the barrel to cool, move the donut and shoot another group. You will eventually find the exact location for the donut-- if you have enough ammo...
 

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The Shadow (Moderator)
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It doesn't dampen barrel harmonics as a whole, but it does address the harmonics of the third order. This is what the Browning B.O.S.S. system also aimed at.
 
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Although I agree with NVSHOOTER that this is a trial-and-error endeavor, I'd start with it near the end of the barrel and work my way towards the receiver.
Just my two cents.

Luisyamaha
 

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a placebo effect with the donut things. A person would be better off focusing on getting the best loading for the gun, no matter what it is...
Probably true, not much will come of it. Assuming this is a sporter rifle, the stock likely has forend pressure built into it. If so, it is already acting on the harmonics. Working up a load will have more effect searching for accuracy than the donut.

If you want to get better results, have a tuner/brake installed, similar to the BOSS, like darkker said.
 

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The Shadow (Moderator)
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jacking with the tail pipe before adjusting the carburetor
Our local NAPA now sells "Muffler Bearings". They typically get asked about them twice a week I'm told :D
 
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Here we go ! ! !

theoretically there is an unlimited potential for the number of tailpipe jokes in the universe. :D
 

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Although I agree with NVSHOOTER that this is a trial-and-error endeavor, I'd start with it near the end of the barrel and work my way towards the receiver.
You are correct. In thinking about it, I remember the instructions were to place the donut something like six to eight inches from the muzzle. I have one of these dampeners, but it's too small to fit over the fat barrel of my target rifle. I never used it. I gave thought to freezing it so that it would be hard enough for me to cut the hole to a larger diameter, but never did it.
 

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jacking with the tail pipe before adjusting the carburetor
Well, yes and no. Working a load should be the first step, if that doesn't get what you want, then a tuner/brake could get the rest. As best as the rifle will deliver given what it is.
 

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Simple-- with somewhat of a learning cruve...

you vary the bullet weight and powder burn rate to locate the pressure peak where the harmonics "go away"
 

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The OP has not mentioned whether or not he is a reloader, and the De-resonator does not require the user to use handloads.

The reloader adjusts his load to match the barrel harmonics.
The non-reloader adjusts the De-resonator to match the barrel harmonics.

A reloader using a De-resonator might have some advantages, but the effort would be great, trying to adjust both at the same time or in series.
 

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The deresonator's instructions tell you where to place it to start with, which depends upon barrel length, and perhaps weight/profile. The instructions then tell you how much to move it as you try it out.

My experience with the deresonator is that it can indeed tighten groups. The BOSS does an outstanding job, IME. The deresonator is at least good. I am a handloader who sometimes shoots factory ammo. :)

Most people I've met have an aesthetic objection to both devices.
 

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Hmmm a little confusing...to come to the conclusion that if a load causes the harmonics you could make a load that matched the harmonics --- like adjusting your prune intake to match your diarrhea problem--- back to the tail pipe.
Where are you confused?

The barrel vibrates when the rifle is fired. The reloader adjusts his load so that the bullet exits the muzzle when the vibration is not at the extreme margins.

Look at this page ~ varmintal.com
 

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but the vibration pattern...

is different for each load, thereby putting the cart before the horse. I'm quite familiar with that website --- great data/????????conclusions.
 

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but the vibration pattern...is different for each load, thereby putting the cart before the horse. I'm quite familiar with that website --- great data/????????conclusions.
The different loads are supposed to change the vibration pattern. But when you're talking carts and horses and tailpipes and diarrhea problems and prune intake and carburetor adjusting, I'm not surprised there is confusion.
 

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Guess things got turned a little sideways...

back in post #14. I was thinking if my O'le -06 was making 3" groups at 300yds with 180gr bullets @ 2600fps and I thought I needed to got a 150gr @ 3100fps but was only getting 12" groups, I might try a "donut" on the barrel even though I knew using the proven loading was a better choice than introducing another variable into the mix.

I'm guessing the donut has a specific location for each different load it stabilizes or do you mark the barrel for each different load, I can't imagine the gadget fixing all your accuracy problems at one location on the barrel. If not I guess I'll put 3 or 4 of them on just in case I see a coyote or bear while deer hunting.
 
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