More on Barrel Tuners

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Jase PTRC
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More on Barrel Tuners

#1 Postby Jase PTRC » Wed May 16, 2018 9:40 pm

I have been reading with great interest here and other forums about tuners, harmonics and compensation. I have some questions about tuners.

I would like to know how to figure out what weight a tuner should be for a specific weight, length and profile barrel?

I have seen plenty about selecting a specific length tuner and harmonic lengths but not really anything related to weights. I see many off the shelf tuners available but surely one weight does not suit all barrels?

Gyro
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Re: More on Barrel Tuners

#2 Postby Gyro » Thu May 17, 2018 8:44 am

http://benchrest.com/showthread.php?61827-Tony-Boyer

Not an answer to your questions Jase but have a look. Mr Boyers' results might suggest the short range shooters don't gotta have one ? BUT maybe the long range shooter can achieve measurable tuner gains as the whole "compensation" thing comes in at the longer ranges. The compensation theories are well accepted by many and have been for a very long time. Good luck anyways.

sungazer
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Re: More on Barrel Tuners

#3 Postby sungazer » Thu May 17, 2018 10:01 am

One thing with Tuners is that as soon as you put any weight on the end of the barrel it is going to change the Jump of the gun. (The jump is the equal and opposite force of the initial explosion and the balance and fulcrum points influence this. In WW2 this jump effect was noticed and no two guns (I am talking artillery here) were the same but it was a constant and adjusted for). So a POI change is assured. The other thing a Tuner is going to do is act like a Barrel crown in someways it will alter or enhance the pressure wave behind the projectile. They are two things that will change without even getting into the Harmonics discussion.
The fundamental harmonic 1st is the pressure wave that may travel down the barrel before the projectile and then reflect back. How many reflections occur before the projectile leaves the barrel?

Gyro
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Re: More on Barrel Tuners

#4 Postby Gyro » Thu May 17, 2018 12:26 pm


Barry Davies
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Re: More on Barrel Tuners

#5 Postby Barry Davies » Thu May 17, 2018 1:45 pm

Take note that with positive compensation it is only applicable to one single distance. At all distances before and after vertical spread still occurs. So for total control over vertical spread you need to compensate at each distance, which can be obtained by various methods, eg, load variation, seating depth variation etc. unless of course you have the ability to produce loads with single figure speed variations.( which tend to give you more constant in bore times)

RDavies
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Re: More on Barrel Tuners

#6 Postby RDavies » Thu May 17, 2018 3:09 pm

Jase PTRC wrote:I have been reading with great interest here and other forums about tuners, harmonics and compensation. I have some questions about tuners.

I would like to know how to figure out what weight a tuner should be for a specific weight, length and profile barrel?

I have seen plenty about selecting a specific length tuner and harmonic lengths but not really anything related to weights. I see many off the shelf tuners available but surely one weight does not suit all barrels?

Ive heard about "The Purdy Prescription" which is supposed to be formulas on dimensions for tuners, but not sure if it also helps with finding the weights as well.

Jase PTRC
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Location: Adelaide SA "PTRC"

Re: More on Barrel Tuners

#7 Postby Jase PTRC » Thu May 17, 2018 7:15 pm

I have been reading about the purdy method Rod. It seems very interesting and i will be sure to experiment with the calculations when i get my new Brux barrel

wsftr
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Re: More on Barrel Tuners

#8 Postby wsftr » Thu May 17, 2018 7:50 pm

A couple of interesting articles on Tuners. Note it does state - "you can have too much of a good thing".
http://www.varmintal.com/a22lr.htm
http://www.varmintal.com/atune.htm

I find positive compensation an interesting concept as the closer you get to the compensated distance the tighter the rifle starts to shoot. A tuner can compensate for FPS variation. This leads to the theory of a tuner setting for each distance shot or a value for short mid and long range where the setting isn't optimal for any specific distance but produces the optimal compromise. i.e a compensation at 950 yards would produce a balance between 900 and 1000 yards. Current fullbore load development requires a load that shoots xs from 300 - 1000 yards. To do this ES must be reduced. To reduce ES/SD it can take many test combinations.

Barry - another thread you asked about tuners. below is a potential way to evaluate them. Its from Varmintal site

[i]WHAT A TUNER DOES.... It is possible to "Tune" a rifle barrel so that where it is pointing at bullet exit time will compensate for small variations of muzzle velocity. In the "tuned" condition the slower bullets are launched at a slightly higher angle than the faster bullets. The difference in launch angle can allow the slower bullets to hit the target at the same elevation as the faster bullets.[/i]

Tune Adjustment Procedure

ADJUSTING THE TUNER.... One way to adjust your tuners to minimize the vertical spread. First, trying to remove the vertical spread, with ammo that is carefully prepared to give consistent velocity and very little vertical, is difficult. The effects of tuner movement on vertical spread will be difficult to see. It makes it difficult to tune out the vertical if there is none.

PREPARE AMMO WITH VERTICAL.... Load ammo WITH a vertical spread built in. Here is a possible test procedure. Test with 6 shot groups. For example, load 3 rounds with your normal load +0.5 gr of powder and 3 rounds with your normal load -0.5 gr of powder. This ammo should exhibit vertical spread. Then adjust your tuner to minimize the vertical spread. Shoot 6 shot groups alternating between the two loads (one high velocity round then one low velocity round. etc.). This procedure would amplify the vertical and better show the effect of the tuner's position on minimizing vertical.
This could be done with the rifle and no tuner to see the magnitude of the vertical and then later with the tuner to show if the tuner does decrease the vertical when adjusted correctly.

sungazer
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Re: More on Barrel Tuners

#9 Postby sungazer » Thu May 17, 2018 7:58 pm

Has anyone ever taken a barrel to a musician or a music store where they have tuning equipment. If a barrel is struck with a metal striker (think like triangle) it will resonate at a certain frequency. I have no idea how this may fit into the equation of barrel tuning but thinking about it i think it would be a parameter than needs to be known if you are going to be using barrel tuners as they will change this frequency and the really only empirical test that can be done is this as you can directly measure and quantify the result.

wsftr
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Re: More on Barrel Tuners

#10 Postby wsftr » Thu May 17, 2018 8:11 pm

sungazer wrote:Has anyone ever taken a barrel to a musician or a music store where they have tuning equipment. If a barrel is struck with a metal striker (think like triangle) it will resonate at a certain frequency. I have no idea how this may fit into the equation of barrel tuning but thinking about it i think it would be a parameter than needs to be known if you are going to be using barrel tuners as they will change this frequency and the really only empirical test that can be done is this as you can directly measure and quantify the result.


Wouldn't you just look at the frequency change on paper?

GSells
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Re: More on Barrel Tuners

#11 Postby GSells » Thu May 17, 2018 9:00 pm

wsftr wrote:
PREPARE AMMO WITH VERTICAL.... Load ammo WITH a vertical spread built in. Here is a possible test procedure. Test with 6 shot groups. For example, load 3 rounds with your normal load +0.5 gr of powder and 3 rounds with your normal load -0.5 gr of powder. This ammo should exhibit vertical spread. Then adjust your tuner to minimize the vertical spread. Shoot 6 shot groups alternating between the two loads (one high velocity round then one low velocity round. etc.). This procedure would amplify the vertical and better show the effect of the tuner's position on minimizing vertical.
This could be done with the rifle and no tuner to see the magnitude of the vertical and then later with the tuner to show if the tuner does decrease the vertical when adjusted correctly.[/i]


Is that at 100m? If it is then a tuner or big nobb ( mass weight dampener ) is doing it's job ! More so the big knob !

With my experience with mass weight dampeners, when they are working , it feels like one can shove a bullet in backwards at 100m and it just shoots ! E.g. it will shoot 1 hole groups with ammo at different load speeds . ( I'M NOT SAYING THAT ANY OLD CLUKER WILL SHOOT ! STILL HAS TO BE GOOD AMMO AND GEAR AND GOOD SHOOTING TO GO WITH IT )!
My 280 ai I've been developing shoots same poi and ragged 1 hole groups at 100 m with 2830,2860,2930,3000 fps . I've been taking bit of a break from major competing at the moment so the development at long range has been limited .But at 800yds it has held its tune and I don't have any reason to believe that it wouldn't continue out to the ton ( time will tell eventually when I come back).
At 500 yds in limited testing at Dalby 2860 load and 2930 fps load both held tune with no major elevation change .25 moa from memory .
This and the experience with the 708 ai and big knobs that I've have observed over couple of thousand rounds now .
Both barrels also ware o rings .
With the 280 ai I made up some fireforming rounds out of 30 06 cases and I stuffed up! I annealled one step early and going from 338 to 7 mm
To create a false shoulder , bulged the neck and put 20 to 30 thou run out! In theory, wasting my time shooting them , was expecting disaster!

This was at CNGRC at 500 yds and 65.5 or 6 ! (66 in Qld second detail !).
I just was caught out in a change !
The buggers just shot ! It would be interesting if we could run the same test with a naked barrel and see? I believe it would be a very different result!
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Last edited by GSells on Thu May 17, 2018 9:48 pm, edited 2 times in total.

GSells
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Re: More on Barrel Tuners

#12 Postby GSells » Thu May 17, 2018 9:18 pm

sungazer wrote:Has anyone ever taken a barrel to a musician or a music store where they have tuning equipment. If a barrel is struck with a metal striker (think like triangle) it will resonate at a certain frequency. I have no idea how this may fit into the equation of barrel tuning but thinking about it i think it would be a parameter than needs to be known if you are going to be using barrel tuners as they will change this frequency and the really only empirical test that can be done is this as you can directly measure and quantify the result.


Yep I don’t using a tuning fork but the above is how I tune orings ! I’m not going to tell u everything in how to tune o rings ! But if u put ur mind to it I’m sure one will work it out !

This method I believe haled First from 22 lr BR shooters . I know some here on this forum find it hard to believe that such a simple thing could make such a difference?

All I can say to you , is give it a try !! It’s only $10 worth of orings !! There are others up here in Qld that have got it to work ! But like anything it won’t correct a bad load or setup or shooter .
But can improve a good barrel that seems like it wants to shoot !
( i'm ready for the pizzling from the keyboard shooters !) :D

Julian D
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Re: More on Barrel Tuners

#13 Postby Julian D » Fri May 18, 2018 2:26 am

If you ask 10 shooters a question on tuning rifles, I would expect about 8 different answers ......
Most people know what works for them.
Experiment for yourself, buy a decent tuner & have a play, most blokes who use tuners & understand them, swear by them, the ones who don't use them reckon they are a waste of time.

It would be no fun if we were all the same.

Gyro
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Re: More on Barrel Tuners

#14 Postby Gyro » Fri May 18, 2018 4:35 am

Another piece of the puzzle for those who want to fill out the picture more fully is to understand the theories of convergence - group convergence - that were held by many for a very long time. Bryan Litz tells us we waz wrong!

Just reading between the lines after reading what Litz had to say about convergence I wonder if perhaps the only reasonable hope left here for the ADJUSTABLE tuner theories, as giving a significant advantage over the same level non-tuner shooter, is for a more thorough understanding of the compensation theories to help us out with our long range accuracy ?

But then of course at the longer ranges the projectile has to travel through a great deal more 'uncertainty' due to us F Class shooters very often ( nearly always ? ) NOT shooting our string through one condition. Different for the BR shooter who works out what's happening from multiple sighters then machine-guns the group away in one condition.
Last edited by Gyro on Fri May 18, 2018 7:21 am, edited 1 time in total.

Gyro
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Re: More on Barrel Tuners

#15 Postby Gyro » Fri May 18, 2018 5:02 am

And Graham why on earth are you still playing with that 280 when everybody knows that loooong powder column aint gonna work. Dont they ?


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