Barrel tuners. Good or a waste of time?

[bcarico]

So, do you tune you load to the best of your capabilities with the tuner at 0 the start turning it out? Or does the tuner screw both ways from zero? If not it would seem you would want to start halfway between zero and maxed out, so you would have adjustment both ways.

 

[rardoin]

Back to tuning.

If I have a great 100 yard tune while using a tuner. Will I be close at 600 and 1,000, or do I need to start over?

Like Mike, my experience is at/less than one graduation from a great tune at 300yds to great vertical at 1000yds. (I do my tuner testing at 300yds and compete in F-class at mostly at 600 and 1000yds). Once I have a solid tune with powder/seating depth it does not take much movement to keep it in tune when changing distances or conditions IME. I have only used a tuner on a single chambering of 6.5mm and only for a little over a year so my experience is limited but still falls in line with others.

 

[savagedasher]

Back to tuning.

If I have a great 100 yard tune while using a tuner. Will I be close at 600 and 1,000, or do I need to start over?

Mine shoots in the 0 at 100 and the Same tune has shot 1 “ At 600
And I’m depending on conditions to do that .
We neve seem to have good conditions at the time we are shooting

I don't think any barrel's muzzle axis angle ever stops; or dwells at some angle for any time.

It's constantly moving up and down for the most part; very little left and right.

The angle has to change to compensate for different muzzle velocities so slower ones leave at a higher angle.

I said dwell time which is incorrect wording
The barrel is moving slower when it is change the direction

 

[ergonsdad]

So, do you tune you load to the best of your capabilities with the tuner at 0 the start turning it out? Or does the tuner screw both ways from zero? If not it would seem you would want to start halfway between zero and maxed out, so you would have adjustment both ways.

[
With the RAS tuners we always start the tune with the tuning ring all the way forward, that is our zero

 

[gunsandgunsmithing]

Mike, This has been a very informative thread, I do have a question (and probably a bit random) but do you see any difference between a heat stress relieved, cryogenically frozen, (or both) barrel(s) in relationship to how much adjusting the tuner might make in comparison to a barrel that has had neither? Just curious. WD

I haven't tested for that specifically but would simply think that it would be relative. Meaning, if it were different at all, it'd be no different than for changing barrels any time. Not sure that makes sense but no, I don't think it would matter. You still start by finding the range of adjustment between completely in tune to completely out of tune and work within that range, at least to start with. From there, if you wish to try the next sweet spot and the next..You would do so as normal. I hope that answers your question Wayne.

 

[gunsandgunsmithing]

So, do you tune you load to the best of your capabilities with the tuner at 0 the start turning it out? Or does the tuner screw both ways from zero? If not it would seem you would want to start halfway between zero and maxed out, so you would have adjustment both ways.

I do as you first described, basically. I run the tuner all the way in, then back it off about 1/2 a turn until zero or whatever number you like is at top. Not a big deal needing both directions, at least for very far as the nodes are so close together, again about 4 marks on my tuner, out of 32 to take it from completely in to all the way out of tune. Mine has about a half inch of travel but there are multiple sweet spots in a single revolution. I prefer to start here, but it really doesn't matter much. I do it because it gives the most thread support for the tuner near the rear most travel. The only place you don't want to set mine is completely bottomed out.

 

[richard]

Wow! Lots of interesting posts on tuners.
You don't need a Phd to run one. They do require a lot of trigger time to figure out how they will work best for you. Several ways of going about all that but I can say Bart S has a good handle on it, his results are very close to what I see. Bottom line, spend time with whatever brand you own. Some work differently than others so it's better to not mix and match during the process of learning.

Richard Brensing

 

[Bart B.]

Mike, This has been a very informative thread, I do have a question (and probably a bit random) but do you see any difference between a heat stress relieved, cryogenically frozen, (or both) barrel(s) in relationship to how much adjusting the tuner might make in comparison to a barrel that has had neither? Just curious. WD

Great question, in my opinion. Here's my take on it.

If one could get barrels from each process with identical to .00001" bore and groove tolerances, and .0001" profile tolerances, then fit them to the same rifle's action, one may well see a difference in tuner settings; after each barrel's been threaded identical so the tuner's zero index is at the same place on each barrel

 

[Bart B.]

Some years ago, I read a report from one of the USA military rifle teams testing their rebuilt M14NM match rifles. There was some positive compensation at 600 yards but none at 200 or 1000. Their reasoning claim was the gas port near mid point on the barrel caused that by bowing the barrel up at that place as it blew gas downward.

 

[GSPV]

Take this FWIW. My experience with tuners is that I leave some tuner room in both directions from my “Zero” setting.

That zero tuner setting is for the temperature where I developed my load. It’s not the tuner’s zero hash, it’s just where the load is in tune at a reasonably standard temperature. I mark that hash with a colored marker.

When I go out to shoot, I make note of the current temperature and how it relates to my “zero” and also the last time that I went out.

While there are multiple spots on the tuner’s revolution that will shoot small groups, half of them are deceptive in that they are ones where your groups are about to blow up.

To cut to the chase, my idea on this is that when you have things dialed in, you want to move to the closest next setting, in the correct direction, that brings the group back in. The one after that one will be one that is bad juju.

In for warmer, out for colder is the correct direction.

Why, you ask? Because the barrel is oscillating. One half of that sine wave is good and provides compensation for the inevitable little errors in Bullet exit point. The other half is bad and aggravates those errors.

YMMV and I’m perfectly OK with that.

Addendum: If I understand my conversations with Dusty correctly, my views on tuning may be biased by score shooting and somewhat dated for short range group shooting. What I’ve been shooting more recently requires not a load/tune that shoots dots but is a struggle to keep up with, but rather one that will reliably hold less than 0.5 MOA at 300 yards. One shot per varmint silhouette, that you sometimes can’t see, and certainly no sighters.

 

[Gene Beggs]

Boy oh boy! Have we ever got some knowledge and wisdom at work with this thread!

Can't wait to see where it's going. And the wonderful thing about it is that most is written in such a way that even redneck country boys like me can understand it.

Keep up the good work guys!

Later,

Gene Beggs

 

[rardoin]

So, do you tune you load to the best of your capabilities with the tuner at 0 the start turning it out? Or does the tuner screw both ways from zero? If not it would seem you would want to start halfway between zero and maxed out, so you would have adjustment both ways.

On the Ezell PDT the graduations are just reference points and where '0' hits relative to the 12:00 position on the muzzle is dependent on the thread start. All three of my tuner threaded barrels, being threaded on a manual lathe and not thread timed, will have '0' on the tuner at varying positions relative to a scribe mark I make on the barrel that marks 12:00 position. On one barrel the two positions I have have utilized are either '26' or '25.5', the latter position being bottomed out against the shoulder. I have had it in a fairly hot shoot that I wished I could have turned it to '25' but it was screwed in as far as I could go. So....to make a short story long, yes, you are thinking correctly. I recommend turning the tuner in until it bottoms out and back off until you have about 1/2 a revolution away from the shoulder to provide the 'elbow' room to go either way on the tuner. I think you will capture the proper 'nodes' in this adjustment range if tuning by Mike's method. This may not apply to Bart S's method as I am unfamiliar with how he utilizes tuners. I hope he does continue to contribute his experience.

 

[Bart B.]

When a rifle is fired the barrel vibrates in four modes: stretching, swelling (OBT), twisting and bending.

If one chooses to compare the muzzle swelling frequency (mode 4 of 8) in Al Harrel's "amode" link I posted earlier to what the OBT theory says it is, you'll see a big difference.

 

[Alex Wheeler]

I dont want to dis-rail this thread so feel free to ignore this, but I wonder how standard vibration analysis truly applies to a hollow cantilevered beam with a traveling mass and a constantly changing pressure behind it? I often wonder if we are not being short sighted by looking at barrel harmonics as if we really understand them.

 

[ergonsdad]

The reason tuning with the RAS tuners are started with the Tuning Ring (TR) tight against the front is that the damping ring is at its max compression. As the TR is moved back the damping and spring rate change aiding in the tune. Damping is a very important part of any vibration management. Tuning is more than just moving a weight around. There are only a few tuners that incorporate damping in their design.

 

[Bart B.]

I dont want to dis-rail this thread so feel free to ignore this, but I wonder how standard vibration analysis truly applies to a hollow cantilevered beam with a traveling mass and a constantly changing pressure behind it? I often wonder if we are not being short sighted by looking at barrel harmonics as if we really understand them.

Some people really do understand them.
Mechanical engineers with modern computer systems have mastered the art of object vibration analysis and predictions. Some for rifle barrels. Others for structures to survive earthquakes.

One very big mistake was the design of a suspension bridge in Washington state. A movie recorded its flaws.

 

[ergonsdad]

I dont want to dis-rail this thread so feel free to ignore this, but I wonder how standard vibration analysis truly applies to a hollow cantilevered beam with a traveling mass and a constantly changing pressure behind it? I often wonder if we are not being short sighted by looking at barrel harmonics as if we really understand them.

Alex you make a very good point. To apply theoretical vibration analysis to all the variables involved in the motion of a fired rifle barrel would be a very daunting task if it was even doable. The other approach is to experimentally build a prototype using the principals of vibration management and change it to get the desired results. It required a few years and over 2,000 rounds of test work to prefect the RAS AR family of tuners. At the end of the day it is more important that it works than all the theory of why it works.

 

[Bart B.]

To apply theoretical vibration analysis to all the variables involved in the motion of a fired rifle barrel would be a very daunting task if it was even doable.

Al Harral and Geoffrey Kolbe have done well using finite element software.

https://www.varmintal.com/atune.htm

 

[Alex Wheeler]

Its pretty obvious to me there is one main vibration pattern, or at least one main one that effects the bullet. You see it in a sine wave target. If there are 8 modes or more, then the others must be pretty small, or they must not effect the bullet trajectory much. I think most of the vibration we "know" about occurs once the bullet has left the barrel.

 

[gpoldblue]

Sounds like very few,if any,have read the book "Rifle Accuracy Facts" by Harold Vaughn.