Litz and Cortina - follow up on barrel tuner discussion

[BoydAllen]

I am fortunate that the local range where I develop loads is a little over 1400' and I can obtain similar temperatures to most ranges where I've competed. When I went to Raton (6600'), we had a practice day and I did reset the tuner. Most of this was with .300 WSM which is a very tolerant cartridge. Seating depth and charge weight both have very wide windows. Combined with a fairly broad tuner range, it often performs quite well. My .284 Shehane does not behave like that and needs more attention.
I shot the Southwest Nationals February in Phoenix and, despite being able to tune in similar conditions, believe that it was out of tune during the match. There is usually no opportunity to evaluate settings during an F-Class match, so had to suffer with it.
I am still shooting Erik's tuners. He sent me one of the V2 tuners and will have some barrels threaded for it when chambered.

Thanks

 

[BoydAllen]

Thanks

Added a few minutes later: Oh THAT Steve Blair. I guess that I should start reading the F Class stuff a lot more often.

Steven Blair « Daily Bulletin

Content tagged with Steven Blair.

bulletin.accurateshooter.com

 

[ImBIllT]

Probably true but it's just remarkable how predictable group shapes are with a tuner. Only a few times out of well over 1000 targets sent to me of my test, have the results not been pretty much exactly as you can predict. At least a couple of those were gun problems or tuner left loose. Astounding how predictable! I'm not a statistician so someone else would have to calculate the probability of me being able to consistently predict the shape of groups for 4-5 marks on either side of a sweet spot near 100% of the time. Think about that for a minute. I'm not the shooter either. That's more than a coincidence or noise.

If you can predict it repeatedly over a large span of groups, then it as almost certainly statistically significant. If you brushed up on your stats then you could better present your information to someone in a way that they could not argue against.

Unfortunately, I’ve both read, and witnessed at the ranch, very strong conclusions being drawn about what is or isn’t working for a particular rifle or barrel based very few targets that are only slightly different. Unfortunately great statistical analysis is difficult to draw within the accurate life of a benchrest barrel, and so you must draw conclusions faster than that. When you know what going up or down on powder, or turning a tuner is going to do, because you’ve seen it 1000 times, and then it does it, an you just have to get it in the zone, then you may have shot only a five shot group, but your sample size(however poorly documented) is tens of thousands of shots. On the other hand, when someone shoots one to two groups with three to five different loads, or tests two different primers, and declares one better than another, I strongly suspect that they are wrong just as often as they are right.

Although I’ve never shot a tuner, the idea that they didn’t do anything, or that anyone else thought they didn’t do anything, never occurred to me. They seem to be universally accepted as useful in or way or another by the short range benchrest shooters that I’ve been around. When I was initially exposed to them folks seemed mostly to get a good load, and stick with it, and adjust the tuner from target to target instead of adjusting the load. The last conversation I heard about it(and since his passing I doubly wish I heard the whole conversation) seemed to be discussing shooting a large array of targets with slight load adjustments on one axis and slight tuner adjustments on the other axis such that both the load and the tuner would approach the perfect position, thus giving a much wider range in which the gun would shoot “in tune”. Something to do with overlapping POI’s got mentioned. Unfortunately I couldn’t quite understand what got said, and only caught the last few sentences, so I’m actually just assuming that’s what had been described, and not sure exactly what was going on.

 

[jelenko]

rarely if ever does a pretty good shooter practice his way to the top

Absolutely. We can see it in all sports/avocations/vocations.
That said, practice and diligence can get a not-super-talented-person well up in the ranks. It takes a while, but they can get there.
I've been watching tennis recently [it's the least bad thing on TV]. You can see the same effect where a occasionally a teenager bursts into the top rankings. At the same time, there are a bunch of 25-28 year olds that have done a bunch of work and get to the top 20 or 30 - some a bit higher. A top 30 tennis player is a really, really good tennis player.

 

[jelenko]

tuner so that the threads are hidden has nothing to do with cosmetics. Rather, I think if the mind sees an inch of threads or so, it assumes you need to use at least a fair portion of them

That's very cool. Human engineering along with mechanical!

 

[ImBIllT]

For generations, the Army and more significantly the Marine Corps assess a rifleman’s potential for “specialized” infantry, presently and into the future, rather quickly and conclusively.

This would suggest that a great deal of tests is not “statistically” necessary, and also that rarely if ever does a pretty good shooter practice his way to the top, so the military is basically saying both Brian Litz’ large sample theory, and the match aspirations of guys like me, are both equally out of luck.

The left side of my brain says the military is absolutely correct on both counts. Indeed, talent surfaces early on in competitive matches, and remains. But the right side of my brain doesn’t care, and is going to shoot its best matches whatever they are til dead.

Bigger differences require smaller sample sizes. The military is far from perfect too.

You cannot shoot a five shot group, make a small change, shoot another five shot group, and declare the small group to be the better method. You must acknowledge that the difference between the two groups could have been from random effects. You could shoot two five shot groups from exactly the same ammo and have one of them measure .150” and another measure .200”. If that’s true, then why would you shoot a .150” group, make a minor change, shoot a .200” group and declare the change to be responsible for the change is group size? A quick brush up on your probability and statistics skills will help you determine what you want to know.

 

[jelenko]

Bigger differences require smaller sample sizes. The military is far from perfect too.

You cannot shoot a five shot group, make a small change, shoot another five shot group, and declare the small group to be the better method. You must acknowledge that the difference between the two groups could have been from random effects. You could shoot two five shot groups from exactly the same ammo and have one of them measure .150” and another measure .200”. If that’s true, then why would you shoot a .150” group, make a minor change, shoot a .200” group and declare the change to be responsible for the change is group size? A quick brush up on your probability and statistics skills will help you determine what you want to know.

Completely agree.

I would add that the same logic applies to the idea of finding a 'flat spot' in velocity by shooting 1 shot at each powder charge.
I try to stay away from inflammatory remarks, but the idea that a flat spot in velocity can be found by shooting 1 shot at each powder charge to be ... well, brain dead.

 

[gunsandgunsmithing]

If you can predict it repeatedly over a large span of groups, then it as almost certainly statistically significant. If you brushed up on your stats then you could better present your information to someone in a way that they could not argue against.

It's the basis for my tuner test that some refer to as a sine wave test. Without that predictability the test would be pretty worthless. I'm constantly amazed at how predictable the group shapes are, myself. Bottom line, tuners are changing what is essentially a constant. The bbl vibrates at basically its natural frequency and the tuner manipulates phase time...even if that frequency changes ever so slightly. So, we have a consistent result on the target.

And yes, I could very much stand to brush up on how I present much of what I try my best to convey. That's part of why I do tuner orders strictly by phone unless you've bought from me previously. I feel much more comfortable speaking directly to someone. You can usually tell when someone "gets it" or not pretty fast and I can spend time on specifics as needed. If I only cared about taking the money, I'd set up an online store and say..."shoot this test and it tells you everything. Thanks for your business." But I don't do it that way because there is so much misinformation out there and I want to be sure that my customer understands the process as deeply as he/she wants or until I run out of the ability to answer questions. I do my very best to give support beyond what is expected and I think it's time well spent.

 

[jackieschmidt]

If I was in this “conversation”, and mentioned using my tuner to induce about a bullet hole worth of vertical in my 30BR VFS Rifle to get out of a horizontal tune, I bet both of these guys would look at me like I was nuts.

 

[Bill Norris]

It's the basis for my tuner test that some refer to as a sine wave test. Without that predictability the test would be pretty worthless. I'm constantly amazed at how predictable the group shapes are, myself. Bottom line, tuners are changing what is essentially a constant. The bbl vibrates at basically its natural frequency and the tuner manipulates phase time...even if that frequency changes ever so slightly. So, we have a consistent result on the target.

And yes, I could very much stand to brush up on how I present much of what I try my best to convey. That's part of why I do tuner orders strictly by phone unless you've bought from me previously. I feel much more comfortable speaking directly to someone. You can usually tell when someone "gets it" or not pretty fast and I can spend time on specifics as needed. If I only cared about taking the money, I'd set up an online store and say..."shoot this test and it tells you everything. Thanks for your business." But I don't do it that way because there is so much misinformation out there and I want to be sure that my customer understands the process as deeply as he/she wants or until I run out of the ability to answer questions. I do my very best to give support beyond what is expected and I think it's time well spent.

I agree Bro. You seem to have a good grip on how they work and what we discussed a few mins. ago makes sense to me. I appreciate your time and efforts to help.

 

[gunsandgunsmithing]

If I was in this “conversation”, and mentioned using my tuner to induce about a bullet hole worth of vertical in my 30BR VFS Rifle to get out of a horizontal tune, I bet both of these guys would look at me like I was nuts.

Not this guy, other than to question if the horizontal had some diagonal and in which direction.

 

[ImBIllT]

Completely agree.

I would add that the same logic applies to the idea of finding a 'flat spot' in velocity by shooting 1 shot at each powder charge.
I try to stay away from inflammatory remarks, but the idea that a flat spot in velocity can be found by shooting 1 shot at each powder charge to be ... well, brain dead.

Well this is one of the most bothersome bits of voodoo and witchcraft that I’ve encountered, but because it strikes me as too asinine for me to waste my time testing, I’ve never bothered to prove it one way or the other and didn’t want to bring it up specifically.

Of course you’ll find a flat spot in velocity if you use small enough increments in powder charge! They usually recommend increments that should cause velocity changes well within a decent ES. Lol. The question is, can you test it 25 times and land on the exact same powder charge almost every time? Maybe. I haven’t tested it because I see absolutely no reason why it should work, and what I do already works as good as I need it to. I suspect it could easily be proven wrong, but I haven’t bothered to try, and can’t promise that it doesn’t work. Even if it does work, I CAN PROMISE, that doing it at just 1-2 shots at each powder charge doesn’t give you the ability to distinguish whether you hit a flat spot or whether your random velocity variation caused it entirely.

 

[ImBIllT]

Bottom line, tuners are changing what is essentially a constant. The bbl vibrates at basically its natural frequency and the tuner manipulates phase time...even if that frequency changes ever so slightly. So, we have a consistent result on the target.

This is one reason that I’m so surprised that tuners aren’t obviously accepted, even though I’ve never used one. From the first time I met a benchrest shooter as a kid the whole description of tuning was related to how long it took the bullet to exit the barrel, and the frequency the barrel naturally vibrated at. It makes perfect sense. I thought that was widely accepted and understood. Well heck, sticking a big weight on the end of the barrel and moving it around would obviously change the frequency the barrel wanted to vibrate at. How is this hard to accept?

I would be far more shocked to discover that someone could prove that tuners didn’t do anything.

 

[gunsandgunsmithing]

This is one reason that I’m so surprised that tuners aren’t obviously accepted, even though I’ve never used one. From the first time I met a benchrest shooter as a kid the whole description of tuning was related to how long it took the bullet to exit the barrel, and the frequency the barrel naturally vibrated at. It makes perfect sense. I thought that was widely accepted and understood. Well heck, sticking a big weight on the end of the barrel and moving it around would obviously change the frequency the barrel wanted to vibrate at. How is this hard to accept?

I would be far more shocked to discover that someone could prove that tuners didn’t do anything.

But both mathematically and realistically, it's not actually frequency that tuners change, but phase time. IOW, moving the sine wave left or right to coincide with bullet exit. The math doesn't support the angular change that is necessary to see the actual results that do happen with such tiny tuner adjustments, but phase time is working with a single waveform and making it be at top or bottom when bullet exit happens. That's why such tiny adjustments are the key and why they can affect poi as much as they can within only say .004-.005" from extreme in tune to extreme out of tune conditions.

 

[DiRTY DOG]

You're spot on brother! It just proved that the tester really didn't know how to use what he was testing. I don't mean that as bad as it may sound because no one knows how to do something until they know how to do it. IOW, no matter the education level an individual possesses, he's uneducated in that specific area and experience/testing has no replacement. Now, he might be able to reverse engineer it and figure it out but starting from what was clearly a blank slate and no real idea of what he was doing...he got the correct results due to the input being garbage(GIGO) vs having a much more informed way of doing it from the start.

One big reason I made my tuner so that the threads are hidden has nothing to do with cosmetics. Rather, I think if the mind sees an inch of threads or so, it assumes you need to use at least a fair portion of them. That is not the case with tuners.

"Nobody has criticized the test methodology." -Litz 1:33:33 min

What?!

 

[gunsandgunsmithing]

"Nobody has criticized the test methodology." -Litz 1:33:33 min

What?!

It was questioned repeatedly, by multiple people.

 

[dcali]

This is one reason that I’m so surprised that tuners aren’t obviously accepted, even though I’ve never used one. From the first time I met a benchrest shooter as a kid the whole description of tuning was related to how long it took the bullet to exit the barrel, and the frequency the barrel naturally vibrated at. It makes perfect sense. I thought that was widely accepted and understood. Well heck, sticking a big weight on the end of the barrel and moving it around would obviously change the frequency the barrel wanted to vibrate at. How is this hard to accept?

I would be far more shocked to discover that someone could prove that tuners didn’t do anything.

The trouble is quantifying what they do. As you say, it's obvious physics that *something* happens when you put a weight on a muzzle and move it. It's easy to fall into the trap of thinking it's as simple as the barrel flopping about with a frequency you can tune. Of course you can do that. But when you dig into it, it gets really hard to explain why moving a tuner that weighs a few ounces out .003" does anything at all. The frequency shift is tiny. Mike keeps telling me its a phase shift. I can't say it's not, but how that happens is not something I can wrap my head around. At this point, the conversation usually devolves into "look, I don't care how it works, I just know it does". That is unsatisfying, and I think we can do better.

The test I would have done would be to instrument a gun and measure the changes in barrel motion, not to shoot groups. It wouldn't be terribly interesting reading, but i think it'd have been far more illuminating. The work Geoffrey Kolbe did is the best I've seen on this, but he tested a rimfire with and without a substantial weight - enough to materially change the vibration frequency. The results were what you'd expect - the barrel slowed down and lined up a better launch. We need that same level of effort put into centerfire tuners if we want to understand them better.

 

[jelenko]

A tuner clamps onto the barrel, yes?

If it does, could it impact the timing of the compression pulse described by Chris Long?

 

[BoydAllen]

A tuner clamps onto the barrel, yes?

If it does, could it impact the timing of the compression pulse described by Chris Long?

Rimfire tuners generally are clamped, CF threaded. Are you sure that winning shooters pay any attention to compression pulses? First rule, study the guys who are winning.

 

[dcali]

A tuner clamps onto the barrel, yes?

If it does, could it impact the timing of the compression pulse described by Chris Long?

OBT is wrong.