A small tuner test

[Matt_3479]

Well I shot a 50 yard tuner test mid winter and found a few settings my gun liked. I got a little busy playing with other calibers and never got around to taking it and tuning further. Well I shot 3 10 shot groups today back to back, 1 on each tuner setting.

I will be retesting later this week then taking it to 300 and 400 to verify but it was nice to see even with such a small sample. Shot at 214 yards

 

[linekin]

We had a 200yd match this weekend. One guy was getting groups like your better one. His rifle is tuned at 50yds as thats the discipline he shoots.
The rest of us more like your other 2 groups. Doesn't take much of a condition change to really screw up the group.
What rifle, barrel, tuner, are you using?
Nice group by the way.
Keith

 

[JimSC]

someone on here recently remarked to me how well a well tuned rifle will buck the wind, that is so true. I am a true believer in the effectiveness of tuners. If it shoots a tight group at 50 there is no reason other than vertical from velocity ES and or shooter error that it won't shoot well all the way out. Good shooting.

 

[Matt_3479]

We had a 200yd match this weekend. One guy was getting groups like your better one. His rifle is tuned at 50yds as thats the discipline he shoots.
The rest of us more like your other 2 groups. Doesn't take much of a condition change to really screw up the group.
What rifle, barrel, tuner, are you using?
Nice group by the way.
Keith

Thank you, I know it’s a small sample at 214 so it’s not much information but it was a good start. This is an ibi 1:12 twist 22” long, vudoo 360 and running a spearhead tuner.

 

[Matt_3479]

someone on here recently remarked to me how well a well tuned rifle will buck the wind, that is so true. I am a true believer in the effectiveness of tuners. If it shoots a tight group at 50 there is no reason other than vertical from velocity ES and or shooter error that it won't shoot well all the way out. Good shooting.

I agree! The groups were shot back to back in similar to same conditions as it was pretty steady and it was interesting to see the horizontal of the group come in.

I shot thousands of rounds at 50 with the tuner just playing around trying to get to know it a bit but it was hard to decipher between the best tunes from there to further. I was told once it’s best to do your tuner testing at your average distance of your matches. If you are shooting 50 yard benchrest then it’s 50 yards, if it’s 100-350 yard prs with the average targets between 150-250 then somewhere around 200 is best.

 

[JimSC]

I was told once it’s best to do your tuner testing at your average distance of your matches.

While I agree it is best to practice at the maximum distance you will be shooting , when testing I believe it is best to minimize and environmental and shooter induced effects that will show the effect of the tuner and or load differance

Newtons first law:

An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force.

Once that bullet leaves the muzzle only gravity and the atmosphere will have any effect on it. Simple physics, no magic involved

Just my opinion, but it is based on science. If you know of any other force that could alter the trajectory after 50 yards I would be interested in learning about it

 

[Matt_3479]

While I agree it is best to practice at the maximum distance you will be shooting , when testing I believe it is best to minimize and environmental and shooter induced effects that will show the effect of the tuner and or load differance

Newtons first law:



Once that bullet leaves the muzzle only gravity and the atmosphere will have any effect on it. Simple physics, no magic involved

Just my opinion, but it is based on science. If you know of any other force that could alter the trajectory after 50 yards I would be interested in learning about it

Oh I agree 100% here I meant it more so that some of the minuscule differences though in the results at 50 may show their differences easier to read at greater distances.

I look at it like load development I guess. Where I start at 100 find my 2 nodes and final tune at 300-500 or whatever I have access to to help show the differences. I never settle on one test as environmentals will play a factor as much as shooter error from day to day. It isn’t perfect but it has been working for me.

My 50 yard thousands of rounds tuner tests helped narrow down the nodes but made it difficult to choose between them for what was best. While my 200 yard tuner test is too small of a sample I will be repeating the test over a few hundred rounds to solidify my decision on which setting. I have been shooting both setting 1 and 16 for my last 2 matches and actually took home a 3rd place and a 2nd place finish with them, but 9 provided a nicer group then either. So I will be repeating the test is 5 10 shot groups at 200 for each setting for a combined total of 6 10 shot groups per setting and make my choice there. If results stay the same I obviously have a winner. If results start to cross over with 2 of the 3 clear winners I will test those two settings more

 

[boltfluter]

At first I thought, wow, those are some sad groups. Until I finally realized you were shooting a .22RF. Nicely done at what I consider to be an extreme range for a RF.
Paul

 

[CharlieNC]

Oh I agree 100% here I meant it more so that some of the minuscule differences though in the results at 50 may show their differences easier to read at greater distances.

I look at it like load development I guess. Where I start at 100 find my 2 nodes and final tune at 300-500 or whatever I have access to to help show the differences. I never settle on one test as environmentals will play a factor as much as shooter error from day to day. It isn’t perfect but it has been working for me.

My 50 yard thousands of rounds tuner tests helped narrow down the nodes but made it difficult to choose between them for what was best. While my 200 yard tuner test is too small of a sample I will be repeating the test over a few hundred rounds to solidify my decision on which setting. I have been shooting both setting 1 and 16 for my last 2 matches and actually took home a 3rd place and a 2nd place finish with them, but 9 provided a nicer group then either. So I will be repeating the test is 5 10 shot groups at 200 for each setting for a combined total of 6 10 shot groups per setting and make my choice there. If results stay the same I obviously have a winner. If results start to cross over with 2 of the 3 clear winners I will test those two settings more

Study Dr Geoff Kolbe article carefully. If velocity differences at 50 yd result in X drop, then the tuner would ideally provide -X angle to offset for perfect positive compensation. Then if the same velocity variability yields 3X moa drop at 100yd, then the tuner is not optimized at X 50yd setting. Same applies to center-fire load tuning.

 

[JimSC]

Using barrel vibrations to tune a barrel

Although the drop will increase more with distance, it will still always follow the mathematical formulae



a group that is round at 50 will remain round at 200 unless a external variable affects it. A tuner simply ensures that the bullets exit the muzzle with the same amount of vertical deflection. Bullet drop and variance is controlled by gravity, wind forces, and bullet imbalance. There is noting about the tune that affects those forces. While in a above post I did say that a tuned rifle seemed to buck the wind better I do know that logically that is because a properly tuned rifle is more likely to produce a round group which equals higher scores.

 

[Matt_3479]

Using barrel vibrations to tune a barrel

Although the drop will increase more with distance, it will still always follow the mathematical formulae

View attachment 1427882

a group that is round at 50 will remain round at 200 unless a external variable affects it. AZ tuner simply ensures that the bullets exit the muzzle with the same amount of vertical deflection

Like I said I am not disagreeing with you, it was just hard to determine at 50 between my top setting choices which one was best as all 3 looked so similar and consistent over hundreds of rounds for just those settings. When the groups at 50 were basically the same size and similar shapes time and time again I figured maybe I’ll see more at distance as it’s only magnified

 

[JimSC]

When the groups at 50 were basically the same size and similar shapes time and time again I figured maybe I’ll see more at distance as it’s only magnified

I agree, at the same time other influences will also be greater. Testing in wind free conditions becomes more and more important as distance increases and any flaws in technique are also magnified with distance.

I was talking with one of the clubs IBS gurus last week and his theory is any flaws in shooter technique is magnified in rimfire benchrest because of the time the bullet spends in the barrel compared to a 6PPC or 30 BR. These little bullets are slow and any wind will really move them around a lot compared to CF

 

[CharlieNC]

Using barrel vibrations to tune a barrel

Although the drop will increase more with distance, it will still always follow the mathematical formulae

View attachment 1427882

a group that is round at 50 will remain round at 200 unless a external variable affects it. A tuner simply ensures that the bullets exit the muzzle with the same amount of vertical deflection. Bullet drop and variance is controlled by gravity, wind forces, and bullet imbalance. There is noting about the tune that affects those forces. While in a above post I did say that a tuned rifle seemed to buck the wind better I do know that logically that is because a properly tuned rifle is more likely to produce a round group which equals higher scores.

But bullets don't leave the barrel at the same time due to differences in velocity, and don't drop the same as a result.

 

[Matt_3479]

I agree, at the same time other influences will also be greater. Testing in wind free conditions becomes more and more important as distance increases and any flaws in technique are also magnified with distance.

I was talking with one of the clubs IBS gurus last week and his theory is any flaws in shooter technique is magnified in rimfire benchrest because of the time the bullet spends in the barrel compared to a 6PPC or 30 BR. These little bullets are slow and any wind will really move them around a lot compared to CF

Yes I agree there too, making it more difficult to get accurate and reliable information as distance increases due to environmentals only adding more and more differentials to each group but if I repeat the test a few times over purely for my curiosity alone and results stay similar then obviously the difference I wasn’t able to pick apart as easily at 50 are showing at 200 for me to pick a better tune for my situation. Even if the groups are double but 9 is still twice as good as 1 and 16 the answer is clear. I’m not saying I’ll be repeating a roughly 1-1.25 moa group time and time again but if that tune provides better averages then it seems to me it’s going work.

Rimfire definitely is humbling. I was told the same thing from guy at my club too. Rimfire will show shooter error significantly more due to time the round spends in the barrels. I am definitely no rimfire guru, and far from a tuner expert. I shoot a lot of rimfire and compete in prs rimfire for fun and just posting my experience thus far.

 

[JimSC]

But bullets don't leave the barrel at the same time due to differences in velocity, and don't drop the same as a result.

the purpose of the tuner is to smooth out the harmonics that the bullets exit the barrel with the same angle of deflection. I agree with what you are getting at with the speed but even allowing for that distance to POI would make no difference in the tuning.

I am pretty new to the rimfire discipline but with centerfire I tuned at 100 and shot out to 800 regularly and occasionally 1000 and never found a load that shot good at 100 that did not shoot good at long range or the other way around tuner or no tuner.

I often wondered how much the ES really mattered. I used a Shotmarker for all my practice and a chronograph for quite a bit and never really saw much if any correlation between FPS and POI. Slower shots would hit higher than faster shots quite often and I always wondered if that had to do with barrel harmonics and the angle of defection where a slower bullet exited that barrel at a higher point in the angle of deflection while the faster bullet exited with the barrel pointed slightly downward.

This is a fascinating hobby for sure

 

[grauhanen]

Using barrel vibrations to tune a barrel

Although the drop will increase more with distance, it will still always follow the mathematical formulae

View attachment 1427882

a group that is round at 50 will remain round at 200 unless a external variable affects it. A tuner simply ensures that the bullets exit the muzzle with the same amount of vertical deflection. Bullet drop and variance is controlled by gravity, wind forces, and bullet imbalance. There is noting about the tune that affects those forces. While in a above post I did say that a tuned rifle seemed to buck the wind better I do know that logically that is because a properly tuned rifle is more likely to produce a round group which equals higher scores.

The Kolbe article in the link is "The Vibrations of a Barrel Tuned for Positive Compensation". The information supports the idea that a rifle can be tuned to generate positive compensation at a given range.

In Kolbe's conclusions it's noted that

The proposition that positive compensation might be achieved by "tuning" a barrel, such that the muzzle angle is changing with time in a beneficial way at bullet launch, is thus a valid one.

The conclusions go on to note that testing showed the following:

The groups fired with the tuned barrel were small and round, showing no sign of vertical dispersion, so demonstrating that positive compensation had been achieved.

The measurement of barrel vibrations in the way demonstrated will be a very quick and positive method of tuning a rifle, requiring very few shots and very little time. Moreover, there is no ambiguity or uncertainty about the result. When the barrel is tuned for complete positive compensation, no further improvement is possible.

This illustration from the Kolbe article shows what positive compensation achieves (with SLOW and FAST referring to MVs of different rounds going to the same POI).



Below is a general question for all readers.

If positive compensation explains how a tuner works, can a tuner that's set at one distance, say 50 yards, continue to generate PC at further distances? In other words, if a tuner causes rounds of different MVs to have a very similar POI at one distance, is it possible for it to cause those same rounds to have a very similar POI at all other distances -- e.g. 75 or 100 or 150 or 200 yards?

 

[CharlieNC]

The Kolbe article in the link is "The Vibrations of a Barrel Tuned for Positive Compensation". The information supports the idea that a rifle can be tuned to generate positive compensation at a given range.

In Kolbe's conclusions it's noted that

The proposition that positive compensation might be achieved by "tuning" a barrel, such that the muzzle angle is changing with time in a beneficial way at bullet launch, is thus a valid one.

The conclusions go on to note that testing showed the following:

The groups fired with the tuned barrel were small and round, showing no sign of vertical dispersion, so demonstrating that positive compensation had been achieved.

The measurement of barrel vibrations in the way demonstrated will be a very quick and positive method of tuning a rifle, requiring very few shots and very little time. Moreover, there is no ambiguity or uncertainty about the result. When the barrel is tuned for complete positive compensation, no further improvement is possible.

This illustration from the Kolbe article shows what positive compensation achieves (with SLOW and FAST referring to MVs of different rounds going to the same POI).



Below is a general question for all readers.

If positive compensation explains how a tuner works, can a tuner that's set at one distance, say 50 yards, continue to generate PC at further distances? In other words, if a tuner causes rounds of different MVs to have a very similar POI at one distance, is it possible for it to cause those same rounds to have a very similar POI at all other distances -- e.g. 75 or 100 or 150 or 200 yards?

Consider a 20fps difference between rounds; at 50yd this will result in X moa difference in poi at 50yd and much more at greater distances simply due to exterior ballistics. There is very limited test data depicting the exact degree of barrel harmonics, but by all accounts the amplitude of vibration is quite small. The results of Kolbe and the few which I have measured suggests tuning changes the exit time on the critical frequency, not so much the amplitude or the frequency itself. So the ability of tuning is typically associated with fine tuning, a wide range of adjustment it not available.

 

[JimSC]

If positive compensation explains how a tuner works, can a tuner that's set at one distance, say 50 yards, continue to generate PC at further distances? In other words, if a tuner causes rounds of different MVs to have a very similar POI at one distance, is it possible for it to cause those same rounds to have a very similar POI at all other distances -- e.g. 75 or 100 or 150 or 200 yards?

First thing that is needed is a understanding of barrel harmonics and what a tuner does.

a 30 minute video on harmonics

 

[MarkS]

I started tuning at 50yds, then at 200yds. Friday I fine tuned my B14R with EC V2 tuner at 200ys with SK Long range. This is 2 - 5 shot groups shot at 400 yds shot with SK Long Range. The wind was 3 to 10 mph. I was just looking for vertical as I was tuning. I knew wind would be pushing right and left. The 2.25" group has 1.5" of vertical, the 2.5" has 1.75" of vertical. I got a good wind condition for these groups, shot a few minutes apart. I know these are not the norm, but are the best groups I have shot at 400yds. I am glad to keep them on a 8" plate at 400yds.. Groups at 200yds run half these in good wind conditions. Tuners really work.

 

[grauhanen]

First thing that is needed is a understanding of barrel harmonics and what a tuner does.

a 30 minute video on harmonics

Thanks for posting the video.

Beginning around 21:48, the video says the following:

"One way to harmonically tune a rifle is to change the harmonics of the rifle by ... changing the [barrel] vibrations in a way that move a node region closer to the muzzle area so that when the bullet exits the muzzle the deflection due to the flopping back and forth of the muzzle is minimized. This is a tuned rifle."

It sounds like this means that the node -- the point at which the vibrations have no (or as little as possible) amplitde -- should be at the muzzle.

If that is what is meant, is the desired goal as little or no change in muzzle angle or position as the bullet exits?