Tuner Testing Part 2

[Dave M.]

Looks like 40 marks on that tuner and 32tpi. So .00078 per mark. Less than a thou. It still amazes me how such tiny adjustments can make a difference. It's because we are shifting phase time, not frequency..per se. If it were frequency, it'd tak much larger increments to have the angular change that we see. But phase time is essentially just manipulating the where the anti-node(tor or bottom of sine) is when the bullet reaches the muzzle...of a single waveform.

Exactly. One full rotation of the tuner only amounts to just a hair over .031”

 

[G7BC]

Glad I can add to the mysteries . I really wish I could have accurate explanations for a lot of the effects and non-effects I find with my testing and I probably could pull it off if I had the means to do so. If you know what the next Powerball numbers are going to be, please let me know and I’m sure the winnings would go a long way in finding explanations . For now, I’ll stick to the practical side of testing and what I’ve learned so far. Without any other further test data and combining my testing with Bryan Litz’s testing, my current practical conclusions and associated guidelines are:
1. The rifle has to have a well-tuned initial load developed. In my case, developing the load with the tuner on and screwed all the way on. This could be a key step in the process that delineate my results from Litz’s because his rifles were not well-tuned prior to turning the tuner.
2. Record all available atmospherics during all shooting with the tuner. This will enable an analysis of the impact of those variables on tune.
3. Shoot the sine wave test and examine closely the group shapes, sizes, and POI.
4. Set the tuner in the middle of a great “tune window” where group shape, size, and POI are very similar and would be considered a good competitive tune.
5. Turn the tuner when atmospherics indicate based on the atmospheric and group data that you have tracked. Examine whether the tune window has possibly shifted in accordance to variations in atmospherics.
As of right now, this seems to be one effective practical method to use the tuner to regain tune. The method is especially useful when preloading for matches where you cannot change your ammo characteristics (e.g., powder charge, seating). As I continue to test more with various different types of tuners in various atmospheric conditions with different barrel contours and chamberings, the guidelines may change but thus far, this is what the data is telling me.

When do you feel comfortable that results have become "Statistically Significant" ? Genuinely curious as I do some testing of my own and want to know when results go from random or by chance to statistically significant. Is it when the pattern repeats itself twice, three times...?

 

[Bryan Z.]

When do you feel comfortable that results have become "Statistically Significant" ? Genuinely curious as I do some testing of my own and want to know when results go from random or by chance to statistically significant. Is it when the pattern repeats itself twice, three times...?

It’s a matter of having the “statistical power” to detect an effect, if any. In general, if you expect a small effect, then you have to shoot a lot. If expect a large effect, then you don’t have to shoot a whole lot. The problem is that there is a lack of published tests out there to estimate whether you expect a small or large effect. However, you could guess based on anecdote. Not ideal but in the circumstance we are in with a dearth of published data, something is better than nothing. For example, if my experience leads me to estimate that something may have an effect of .1MOA, I know I’ll have to shoot over 10 5-shot groups for each experimental condition to have the power for statistical significance. If I expect it to be .5MOA then I don’t have to shoot 10 groups to detect the effect.

Also, at this point after doing several tests and having over 25 years of experience with stats, I can estimate when a test will have the power to detect a difference as I am in the process of shooting a test. Please feel free to send me test data and I can advise.

 

[G7BC]

It’s a matter of having the “statistical power” to detect an effect, if any. In general, if you expect a small effect, then you have to shoot a lot. If expect a large effect, then you don’t have to shoot a whole lot. The problem is that there is a lack of published tests out there to estimate whether you expect a small or large effect. However, you could guess based on anecdote. Not ideal but in the circumstance we are in with a dearth of published data, something is better than nothing. For example, if my experience leads me to estimate that something may have an effect of .1MOA, I know I’ll have to shoot over 10 5-shot groups for each experimental condition to have the power for statistical significance. If I expect it to be .5MOA then I don’t have to shoot 10 groups to detect the effect.

Also, at this point after doing several tests and having over 25 years of experience with stats, I can estimate when a test will have the power to detect a difference as I am in the process of shooting a test. Please feel free to send me test data and I can advise.

Something that was huge for me was learning that you're generally only going to be making a very minor adjustment to bring the load back in. Have you continued to work on this and feel like BP is a reliable indicator of what setting to run?

 

[gunsandgunsmithing]

Something that was huge for me was learning that you're generally only going to be making a very minor adjustment to bring the load back in. Have you continued to work on this and feel like BP is a reliable indicator of what setting to run?

Hopefully Bryan will reply but per his videos, he simply doesn't see the wide temp swings in his part of the country that most of us do experience. So, I think he uses what's before him, which is what we all should be doing, IMHO. He was able to correlate tune changes to bp because that's what was driving the changes in HIS location.
In most of the country, we see far wider temp swings and I've found temp to be of approximately 4x more value to tune than bp. I agree with virtually everything he found but we simply live about 2500 miles apart and have very different weather conditions to test within. Just remember this and you can't go wrong...smokeless powder turning from a solid to a gas is a chemical reaction and ALL chemical reactions are temperature dependent to varying degrees. That's not theory but fact.

I do find bp, or more specifically, I watch station pressure..to be the 2nd most important factor to tune. I guess if you see 10° change in one part of the country and 40° in another, the two would be very different if the pressure change were the same at both...That's theory but is supported by lots of testing over the last 17 years approximately.

 

[G7BC]

Hopefully Bryan will reply but per his videos, he simply doesn't see the wide temp swings in his part of the country that most of us do experience. So, I think he uses what's before him, which is what we all should be doing, IMHO. He was able to correlate tune changes to bp because that's what was driving the changes in HIS location.
In most of the country, we see far wider temp swings and I've found temp to be of approximately 4x more value to tune than bp. I agree with virtually everything he found but we simply live about 2500 miles apart and have very different weather conditions to test within. Just remember this and you can't go wrong...smokeless powder turning from a solid to a gas is a chemical reaction and ALL chemical reactions are temperature dependent to varying degrees. That's not theory but fact.

I do find bp, or more specifically, I watch station pressure..to be the 2nd most important factor to tune. I guess if you see 10° change in one part of the country and 40° in another, the two would be very different if the pressure change were the same at both...That's theory but is supported by lots of testing over the last 17 years approximately.

So, say hypothetically on relay 1 it's 65F you are hammering the x-ring . Relay 2 it's 80F now and load starting to loosen up a bit, still clean but fewer X's. Now , it's 90 and you're about to start Relay 3 and want to make an adjustment to try to tighten things up , what do you do? (A lot of variables here , I know but just a quick and dirty attempt at trying to get back in tune) I have heard when things start to warm up, you want to turn towards the shooter?

 

[gunsandgunsmithing]

So, say hypothetically on relay 1 it's 65F you are hammering the x-ring . Relay 2 it's 80F now and load starting to loosen up a bit, still clean but fewer X's. Now , it's 90 and you're about to start Relay 3 and want to make an adjustment to try to tighten things up , what do you do? (A lot of variables here , I know but just a quick and dirty attempt at trying to get back in tune) I have heard when things start to warm up, you want to turn towards the shooter?

I find that to be correct most of the time. Simply put, we're speeding the bbl up to keep up with a faster bullet exit time.

Where it gets more complicated is that pressure has the opposite effect. There are days that the same temp change, say 70-90, has little or no effect on tune while the very next day, it does. If it we're as simple as graphing temp/pressure, we'd have done it but it's not. That's why I tune by group shapes.
I'll post a pic of my test target. It tells me which way and by how much to move my tuner because the group shapes along with poi changes are predictable and repeating.
It's laid out for my tuner though because I know values for it that may or may not apply to others. Step one with any tuner is establishing the value on target of any incremental change of your tuner. If you don't know that, no other way to put it...you're just moving and hoping.

 

[gunsandgunsmithing]

This is the centerfire test target. Every single detail, down to making your own target just like it matters. It IS the shortcut! Again, I know values for my tuner that make this test golden. It may or may not be enough groups to go through a full nodal cycle with other tuners and Mark values may be different. Its not easy to establish those all important values. Ive done the work on mine and this test works with it. Ever wonder why some tuners have different markings? Did they plan that with a purpose or not? Why do some people say move 1 mark, 2 marks, 5 marks at a time or even in full turns? If they can't give specific expectations for group shapes with whatever change they suggest, I'll let you decide what to make of their suggestion.

 

[G7BC]

Thanks Mike.

 

[gunsandgunsmithing]

Thanks Mike.

I'll add this and gotta get to work. Twice I've seen tune change all of a sudden, dramatically and rapidly. Only twice and both times were with steady temps and a tornado warning.(massive bp drop) That had to be pressure and both times, I had to go opposite with the tuner than what I would've thought. Remember I said pressure has an opposite effect vs temp?
Tune doesn't typically change dramatically IF tuned to top or bottom poi. There really is a method to the madness and none of it is magic.

 

[Bill Norris]

I'll add this and gotta get to work. Twice I've seen tune change all of a sudden, dramatically and rapidly. Only twice and both times were with steady temps and a tornado warning.(massive bp drop) That had to be pressure and both times, I had to go opposite with the tuner than what I would've thought. Remember I said pressure has an opposite effect vs temp?
Tune doesn't typically change dramatically IF tuned to top or bottom poi. There really is a method to the madness and none of it is magic.

I too have seen this reverse situation against erratic weather changes. But what I did find was the amount of turning the tuner was still small as opposed to the wide range the tuner rotations affords.

 

[gunsandgunsmithing]

I too have seen this reverse situation against erratic weather changes. But what I did find was the amount of turning the tuner was still small as opposed to the wide range the tuner rotations affords.

Once the extreme from node to anti-node is established, I've never seen a condition take it out more than that. On my tuners, that's 4-5 marks. This is where group shape and poi are telling you a lot. You're just breaking that half cycle down into 4 or 5 increments ..on my tuner. 4 or 5 group shapes is it. You quickly recognize when you're close, far or in tune. Easy.