Barrel Tuner or Wieght?

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jasmay
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Joined: Fri Sep 28, 2012 9:26 pm

Barrel Tuner or Wieght?

#1 Postby jasmay » Tue Mar 22, 2016 6:32 am

Hi Guys, for a while now I have been playing with the idea of a tuner or barrel weight, I've read some interesting articles on them but what I haven't found is anything that explain when the application of one of the two is warranted, I have a barrel that seems to be performing very well, should I put one on anyway, or am I better to tweak loads when conditions demand?

Will a fixed weight be an easier or perhaps better option for a barrel that is already performing well?

Confused on tuners... :?

williada
Posts: 742
Joined: Wed Jul 22, 2009 12:37 am

Re: Barrel Tuner or Wieght?

#2 Postby williada » Tue Mar 22, 2016 9:37 am

Jason,

If your barrel is performing well don’t add anything to it. You can make things overly complex. As I have said several times before, “If it ain’t broke don’t fix it. Tight is tight, is tight. I wrote about the ultimate, because I believe in setting goals and there are those people in our competition who like to read technical stuff and master it and are capable of doing it. At some stage they all crawled before they walked.

My personal view is you really need more than one rifle, one for the shorts and one for the longs. If you want to be theoretically correct you would want one for the shorts, one for the mids and one for the longs. What dominates the overall performance with each barrel is the launch angle which tosses the projectile out for these different distances. That relates to the barrel’s compensation profile. No amount of tight load development up short will recover a barrel throwing slow shots low at one thousand yards i.e. negative compensation.

Back to the chase, if your barrel is underperforming and your load development cannot find a solution; and you generally shoot one rifle across all distances then a barrel weight will dampen the amount of barrel lift and therefore launch angle and so it is a bit of a compromise as to how much weight you add to get the launch angle right. Then this is backed up with top reloads. The best compromise solution is to have a rifle that is mildly positively compensating which you can see in your load development. The downside of a heavy weight is bag handling, particularly on a downhill range.


If your load development can’t tighten your groups, and there is nothing obviously wrong with your rifle mechanically or a worn barrel, then the harmonic length of your barrel is wrong. That means all the many harmonic waves produced and reflected in a barrel are not working in balance on bullet exit. I generally think it is the harmonic length that determines how tight your groups can be. A way of accommodating the harmonic optimum is to add a variable tuner which extends past the barrel muzzle to fool the barrel into thinking it’s the right harmonic length. Or you can back-bore, but you lose velocity.

Unless you like a challenge and understand which way to move a variable tuner or set it up, you are wasting your time. It becomes no different to a barrel weight which you set and forget.

Let’s run through some complexities of variable tuners. Firstly, any old variable tuner will not do. It should be a custom tuner based on the harmonic length of your barrel, then the tuner length adjusted to match. Sometimes the tuner thimble has to be moved past the end of the bloop tube it rides on if you have not got the bloop tube length right - another compromise. Secondly, the weight of the variable tuner should be sufficient to change the launch angle – particularly if the curvature of the barrel has been fitted by the gunsmith in the wrong plane and pushes out negative compensation. Thirdly, when the launch angle and harmonics have been sorted, assuming the internal diameter of the tuner manages the flack (particles), the movement of the tuner thimble for fine tuning is a compromise between adjusting the launch angle for mainly elevation tightening at a particular distance or the harmonics for general group size because there is an overlap between the compensation tune and the pure nodal tune. And sometimes we move the thimble back or forward depending on whether you tune about a trough or a peak in the sine wave of load development. This is confusing to some. When you have it right only tiny movements of the tuner thimble are required. For the masters, then the variable tuner can be used to finely adjust for distance, mound angle, and atmospheric density change. This is really challenging and just copying a fashion does not work unless you have been trained how to use it properly or are willing to experiment. What are you doing for the next 40+ years?

In closing, and in the words of Cam, “I would not put a fly on my barrel”. He was referring to the Magneto Speed when doing load development. Unless you can duplicate the weight of the Magneto Speed on your muzzle as a barrel weight, it will change your launch angle and to some degree the harmonics because there is always an overlap or interaction. The long and short range results of your setup will be compromised. Sure, use one for a velocity figure. Hope this helps. This is the very reason the ”Train the Trainer” program in load development is being conducted, so people know why and how things work to increase the super centre count. David.

jasmay
Posts: 989
Joined: Fri Sep 28, 2012 9:26 pm

Re: Barrel Tuner or Wieght?

#3 Postby jasmay » Tue Mar 22, 2016 10:34 am

Thanks for the reply David, clears up some decisions I've been struggling to make.

BRETT B
Posts: 208
Joined: Fri Sep 30, 2005 2:37 pm
Location: PERTH

Re: Barrel Tuner or Wieght?

#4 Postby BRETT B » Tue Mar 22, 2016 10:48 am

Hi Jason , FWIW I was in the same position as you last year wondering if I should or shouldn't.. I ended up getting a Tuner from Eric Cortina in America and put it on one of my 7mm barrels. I had already had this barrels tuned and had it shooting quite good so I could see what the Tuner did. I will say I am now glad I did it as a learning experience and will continue to use it and learn the Tweeks. As this was my first experience with a tuner I think putting it on a secondary or all ready tuned barrel instead of new one helped me to workout how the Tuner affects grouping without getting too confused..
BRETT BUNYAN F CLASS OPEN SHOOTER W.A.

williada
Posts: 742
Joined: Wed Jul 22, 2009 12:37 am

Re: Barrel Tuner or Wieght?

#5 Postby williada » Tue Mar 22, 2016 11:28 am

Brett, I hope Brad adds to your comments as you are on the right track putting the tuner on a tuned barrel i.e a barrel which you have previously finished the load development.

Brad Y
Posts: 2022
Joined: Fri Jun 26, 2009 8:21 pm

Re: Barrel Tuner or Wieght?

#6 Postby Brad Y » Tue Mar 22, 2016 3:18 pm

I hope you werent referring to me as I cant help him! Im the one who needs all the help I can get to stop the bunyan train at prize shoots across WA [-o<

As of yet, variable tuners arent on my to do list but Im interested in trying one when funds and components are available to do the tweaking when loads go in and out of tune. Lately Ive been able to spend the time and components and develop loads for my long and short range barrels that shoot very well without any modification to the barrel itself. However I have added a fixed weight to both my 7mm's purely for the reason of extending the size of the node to allow for variations in temperature/humidity/barrel temp etc that can throw tune out the window during a shoot. I still think- like Brett- you need to do the hard work on a barrel before you can put something on the muzzle and expect results. Im lucky to not have to do the other part of the hard work afterwards and have to worry about tweaking a tuner at the moment. Also lucky theres been no negative results from adding taper bored weights, and locktite 243 to keep them there, onto my barrels to extend the size of the accuracy nodes.

I did have one barrel that I had alot of trouble with- and tried a 900gr adjustable weight on it to get it going and it was a waste of time and money. So that proves it wont make a bad barrel good- but it can definitely make a good barrel great.

If your new to them, I would recommend the fixed weight on an already proven barrel to get your feet wet, then when your next barrel mimics the first, do an adjustable tuner to see if you can better the first setup.

williada
Posts: 742
Joined: Wed Jul 22, 2009 12:37 am

Re: Barrel Tuner or Wieght?

#7 Postby williada » Tue Mar 22, 2016 4:05 pm

Yes, Brad it was you. I wanted to hear your comments having added a fixed weight. This is a different perspective. What you said, is exactly what I wanted to hear, as you are learning mastery before or if you move to the next stage. Of course Brad did his load development before adding his fixed weight. As I don't want to embarrass him, I think his next competitive shoot with the load development and a muzzle weight was a double possible, one of which had ten supercentres. :mrgreen: Correct me if I was wrong. :oops: David.

Brad Y
Posts: 2022
Joined: Fri Jun 26, 2009 8:21 pm

Re: Barrel Tuner or Wieght?

#8 Postby Brad Y » Tue Mar 22, 2016 11:11 pm

Yes straight up 60.10 at 600yds with the short range barrel and 168gr vld's. Shot a 60.9 a couple of weekends ago at 300yds too. Mind you this range that we are on while ours is closed is quite easy to shoot good scores on some days- but the gun still has to be capable.

Ive said it before, with the fixed weight in these barrels and shooting groups at short range, it almost seems as though they are in tune with the weight off, but with weight on they are in a super tune and group amazingly tight. Though I will admit Ive also said to some people who asked, that the weight is there purely so I can carry the gun off the mound by the barrel and the knob stops the gun slipping out of my hand... :twisted:

plumbs7
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Joined: Wed Feb 12, 2014 7:32 am
Location: Dalby/ Tara Rifle Club

Re: Barrel Tuner or Wieght?

#9 Postby plumbs7 » Mon Apr 04, 2016 6:18 pm

The difference is subtle! To make the most of the tune the shooter , load and gear have to be at their best to notice it! In our development squad 3 of us have fixed weights, mine is nearly 600 grams and looks like I'm compensating a lot more than just barrel harmonics lol! Does it work ? I think so but its not huge!


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