Positive compensation and its explanations .

[kthomas]

Yea we got it . You say that same statement about almost every post for a year now . If you can contribute to the tuner with your testing then by all means please do so . But if you are going to repeat the same posts over and over , then that is not helping .. the intent is to help shooters adjust tuners , not to discuss your version of testing .

My own testing won't be able to control all the variables - just like the vast majority of individuals. A simple waterline can't draw the conclusions we are asking it to do in this thread.

Anyways, I only posted because someone asked. This is a discussion forum - I feel like open discussion from all perspectives is allowed. And tuners will only be able to advance if those advocating them open themselves up to questions and critique.

I have no skin in this fight. I'm out.

 

[Long Range 338]

Personally, it's something I would like to see tested more to validate.

Most of our knowledge/ideas on barrel movements seems to be based on models performed decades ago.

It's a big underlying assumption behind a lot of tuner hypothesis'. It would be really interesting to see how the real world actually lines up with those models - and that new understanding would only help progressing tuners.

So being a shooter, not an engineer or scientist I am completely oblivious to the existing scientific data on the subject. However I am aware of the structured barrels from TacomHQ and am under the impression they are an accepted method of controlling barrel harmonics. Does any of this carry over from one technique to another?

 

[timintx]

So being a shooter, not an engineer or scientist I am completely oblivious to the existing scientific data on the subject. However I am aware of the structured barrels from TacomHQ and am under the impression they are an accepted method of controlling barrel harmonics. Does any of this carry over from one technique to another?

I have heard great things about tacom barrels , what he does is amazing . I have friends that use them as well.It is never a bad thing to reduce the bending .

 

[timintx]

One thing I would add is that I’d you reduce the bending a tuner is not going to help much so it depended on the amplitude or the bending in which a tuner adjustment will show up as to the effects . Bearing in mind a tuner shifts the phase of movement , but if there is no movement then a shift of phase is the same in all areas of that particular movement . So if you have a flatline on the graph, you won’t see much with the tuner adjustment.

 

[Macht]

Unfortunately there is no way to measure precise barrel movements other than graphs or ladder tests followed by multiple distance target confirmation with two different velocities.

I have to assume the guys at the ARL must occasionally read forums like this so they can wet themselves laughing. They've been doing it for 10+ years and have the capability directly integrated into the rifle mount in their spark range.

The most recent publications with that kind of data were based on measurements from laser displacement sensors, whereas the older data was obtained with eddy current sensors.

 

[kthomas]

So being a shooter, not an engineer or scientist I am completely oblivious to the existing scientific data on the subject. However I am aware of the structured barrels from TacomHQ and am under the impression they are an accepted method of controlling barrel harmonics. Does any of this carry over from one technique to another?

And this is the problem we all face as shooters.

There is very little, if any rigorous scientific testing being done to help shooters out on subjects such as this.

Instead, we rely on flawed tests and our own observations in order to draw conclusions. And from knowledge handed down by other shooters, that was also drawn from incomplete and flawed testing and observations.

And this is why every reloader has a different understanding of what processes work and don't work. Of what variables matter and what doesn't. And why every tuner advocate has a different story for what tuners do and how to use them. Because everyone is operating off of very incomplete data and analysis.

The structured barrel concept is neat. I'm not sure how well it works in reality. No experience with it.

 

[kthomas]

I have to assume the guys at the ARL must occasionally read forums like this so they can wet themselves laughing. They've been doing it for 10+ years and have the capability directly integrated into the rifle mount in their spark range.

The most recent publications with that kind of data were based on measurements from laser displacement sensors, whereas the older data was obtained with eddy current sensors.

What's the ARL?

 

[Huskydriver]

What's the ARL?

Allegany ballistics laboratory I'm assuming

 

[Long Range 338]

I have to assume the guys at the ARL must occasionally read forums like this so they can wet themselves laughing. They've been doing it for 10+ years and have the capability directly integrated into the rifle mount in their spark range.

The most recent publications with that kind of data were based on measurements from laser displacement sensors, whereas the older data was obtained with eddy current sensors.

What conclusions did they arrive at with their new techniques and were they different from the previous ones? If there is any definitive study out there I am all ears.

 

[kthomas]

What conclusions did they arrive at with their new techniques and were they different from the previous ones? If there is any definitive study out there I am all ears.

I agree.

This would be really interesting to see.

 

[Long Range 338]

The most obvious in this thread is that it took the dumbest guy in the room (myself) asking the least technical questions to stir some very informative input from all involved. LOL

Thank You

 

[Long Range 338]

@timintx

For ELR shooting, what distance is best to use for doing the graph testing? Is this similar to typical ladder testing that needs to be done at 200 or 300 yards? It seems that most of yours is done at 100?

 

[Macht]

What's the ARL?

Army Research Laboratory in Aberdeen, Maryland. Some of their technical reports (the unclassified ones) are available through DTIC. They will also occasionally publish in journals or in conference proceedings but those are typically pay walled.

If I understand the history correctly, the system was developed to help break total jump into its components and the sensors give you both lateral barrel velocity and pointing angle.

 

[kthomas]

Army Research Laboratory in Aberdeen, Maryland. Some of their technical reports (the unclassified ones) are available through DTIC. They will also occasionally publish in journals or in conference proceedings but those are typically pay walled.

If I understand the history correctly, the system was developed to help break total jump into its components and the sensors give you both lateral barrel velocity and pointing angle.

That is really interesting, I'll have to try and find some of this information. This is the kind of stuff I would love to see.

 

[Macht]

What conclusions did they arrive at with their new techniques and were they different from the previous ones? If there is any definitive study out there I am all ears.

They weren't testing tuners or anything like that. It's been a year or so since I last looked at the paper, but I think they were looking at the repeatibility of different fixtures for mounting M4s.

My only point is that the technology to measure barrel movement is available and has been so for years.

 

[kthomas]

They weren't testing tuners or anything like that. It's been a year or so since I last looked at the paper, but I think they were looking at the repeatibility of different fixtures for mounting M4s.

My only point is that the technology to measure barrel movement is available and has been so for years.

I'm not surprised.

There are probably a few industries that have technology that could be utilized to map out a barrel in 4D.

It's unsurprising that the army is doing it. This is the kind of technology that should be used to prove the underlying assumptions behind positive compensation, and to understand how and to what extend tuners "work".

 

[timintx]

@timintx

For ELR shooting, what distance is best to use for doing the graph testing? Is this similar to typical ladder testing that needs to be done at 200 or 300 yards? It seems that most of yours is done at 100?

I would not recommend it , for the most accurate graphs I would shoot at 100 yds to eliminate as chances of errant shots due to wind .

 

[timintx]

I have to assume the guys at the ARL must occasionally read forums like this so they can wet themselves laughing. They've been doing it for 10+ years and have the capability directly integrated into the rifle mount in their spark range.

The most recent publications with that kind of data were based on measurements from laser displacement sensors, whereas the older data was obtained with eddy current sensors.

I will follow up on that , thank you for the info.

 

[Rio Precision Gunworks]

They weren't testing tuners or anything like that. It's been a year or so since I last looked at the paper, but I think they were looking at the repeatibility of different fixtures for mounting M4s.

My only point is that the technology to measure barrel movement is available and has been so for years.

I wasn't going to go down this road, since it wasn't going to be productive. But yea, most of this stuff has already been looked over by some very sophisticated labs for both .mil and civilians.

Other than that, there is no conversation to be had when people are claiming they can test as good as better as actual purpose built labs and companies via shooting paper and steal.

 

[Ledzep]

I have to assume the guys at the ARL must occasionally read forums like this so they can wet themselves laughing. They've been doing it for 10+ years and have the capability directly integrated into the rifle mount in their spark range.

The most recent publications with that kind of data were based on measurements from laser displacement sensors, whereas the older data was obtained with eddy current sensors.

What you find from those setups is that the bulk of dispersion is not caused from muzzle movement and is left up to interpretation a little bit, but is most likely from in-bore yaw and a few other factors. The trend between muzzle movement (position and angle) and bullet POI is weaker than most would assume. Bear in mind this is from my recollection of conversations months ago and is not all-inclusive. Only generally speaking to things that had been tested. No idea if tuners were on that list but I doubt it.

 

[Macht]

What you find from those setups is that the bulk of dispersion is not caused from muzzle movement and is left up to interpretation a little bit, but is most likely from in-bore yaw and a few other factors. The trend between muzzle movement (position and angle) and bullet POI is weaker than most would assume. Bear in mind this is from my recollection of conversations months ago and is not all-inclusive. Only generally speaking to things that had been tested. No idea if tuners were on that list but I doubt it.

That jives with the conversations I had there as well. On a separate note, possible exceptions to that rule are auto fire and open bolt guns.

 

[timintx]

What you find from those setups is that the bulk of dispersion is not caused from muzzle movement and is left up to interpretation a little bit, but is most likely from in-bore yaw and a few other factors. The trend between muzzle movement (position and angle) and bullet POI is weaker than most would assume. Bear in mind this is from my recollection of conversations months ago and is not all-inclusive. Only generally speaking to things that had been tested. No idea if tuners were on that list but I doubt it.

I agree , in my testing it appears it is a combination of 4 factors , muzzle position , lateral muzzle velocitiy ,in bore yaw and CG offset which in turn creates a larger aerodynamic jump at the muzzle especially with suppressors. My suppressor designs will negate those effects .

 

[Taylorbok]

Your barrel will need a tuner around 3 pounds. I have a tuner on one of my heavyguns and it was made by Scott "Fudd" Hamilton at 51 ounces but I am using a 9 inch barrel block.

Here is the movable weight tuner that I used in 1000 yd Benchrest .

I've talked with some machinist friends and figure we should be able to make a tuner brake similar to what Cortina makes. If the whole assembly is going to weigh in the neighborhood of 3 lbs how heavy should the adjustable portion should be?

Also anyone tried these Insite Arms tuner brakes? Thoughts?

 

[CNC-Dude]

I've talked with some machinist friends and figure we should be able to make a tuner brake similar to what Cortina makes. If the whole assembly is going to weigh in the neighborhood of 3 lbs how heavy should the adjustable portion should be?

Also anyone tried these Insite Arms tuner brakes? Thoughts?
View attachment 8248771

I made one based on his new V2 design. It works pretty good....just a tuner, no brake!

 

[cameljockey230]

I've talked with some machinist friends and figure we should be able to make a tuner brake similar to what Cortina makes. If the whole assembly is going to weigh in the neighborhood of 3 lbs how heavy should the adjustable portion should be?

Also anyone tried these Insite Arms tuner brakes? Thoughts?
View attachment 8248771

The tunable mass would weigh 48 ounces but if the brake is past the muzzle you can deduct its weight from the movable mass.

 

[cameljockey230]

I'm not surprised.

There are probably a few industries that have technology that could be utilized to map out a barrel in 4D.

It's unsurprising that the army is doing it. This is the kind of technology that should be used to prove the underlying assumptions behind positive compensation, and to understand how and to what extend tuners "work".

A barrel is just a piece of steel pipe and engineers have been studying how it bends for quite some time now.

 

[TheOfficeT-Rex]

Popping back in with a couple questions for the collective braintrust-

I shot this test at 100 yards. I am trying to use the positive compensation tuner method. Each aimpoint is a pair fired at a different tuner setting. Blue rounds are loaded under nominal charge (slow), green ones are loaded higher (fast). There was a 60 fps difference between them.

The conclusions I’ve drawn from this target are (please tell me where and why I’m wrong or I missed something):

• The best setting for 100 yard shooting is 3, because it has the lowest vertical spread while still having the slower round impact higher. It is tuned for this distance.
• For positive compensation at distance, setting 8 is best because it delivers the slower round higher.
• The worst of any setting is 21, because of the large vertical spread with faster rounds hitting higher.

My question:

• If I use my normal ammunition, should I be able to discern any differences between these settings at 100 yards if I fire groups?

Thanks all.

 

[JBoomhauer]

All signs point to 72

 

[Rio Precision Gunworks]

Popping back in with a couple questions for the collective braintrust-

I shot this test at 100 yards. I am trying to use the positive compensation tuner method. Each aimpoint is a pair fired at a different tuner setting. Blue rounds are loaded under nominal charge (slow), green ones are loaded higher (fast). There was a 60 fps difference between them.

View attachment 8266895

The conclusions I’ve drawn from this target are (please tell me where and why I’m wrong or I missed something):

• The best setting for 100 yard shooting is 3, because it has the lowest vertical spread while still having the slower round impact higher. It is tuned for this distance.
• For positive compensation at distance, setting 8 is best because it delivers the slower round higher.
• The worst of any setting is 21, because of the large vertical spread with faster rounds hitting higher.

My question:

• If I use my normal ammunition, should I be able to discern any differences between these settings at 100 yards if I fire groups?

Thanks all.

Shoot the exact same test 5 different days and post the pics.

Then we can pick a setting/s and test the dispersion of said setting.

 

[Rio Precision Gunworks]

Popping back in with a couple questions for the collective braintrust-

I shot this test at 100 yards. I am trying to use the positive compensation tuner method. Each aimpoint is a pair fired at a different tuner setting. Blue rounds are loaded under nominal charge (slow), green ones are loaded higher (fast). There was a 60 fps difference between them.

View attachment 8266895

The conclusions I’ve drawn from this target are (please tell me where and why I’m wrong or I missed something):

• The best setting for 100 yard shooting is 3, because it has the lowest vertical spread while still having the slower round impact higher. It is tuned for this distance.
• For positive compensation at distance, setting 8 is best because it delivers the slower round higher.
• The worst of any setting is 21, because of the large vertical spread with faster rounds hitting higher.

My question:

• If I use my normal ammunition, should I be able to discern any differences between these settings at 100 yards if I fire groups?

Thanks all.

You can also just shoot number 3, 8, and 21 over a few times.

See if they repeat your observation.

 

[TheOfficeT-Rex]

All signs point to 72

I honestly expected 42, but you're probably right.

Shoot the exact same test 5 different days and post the pics.

Then we can pick a setting/s and test the dispersion of said setting.

Lets say that I was going to shoot the best and worst on the same day as this test (as if a match format, and these were my sighters).

 

[Rio Precision Gunworks]

I honestly expected 42, but you're probably right.


Lets say that I was going to shoot the best and worst on the same day as this test (as if a match format, and these were my sighters).

You could do something like shoot the best and worst for 20 shots each. Then compare. That'll let you know how much "improvement" you have.


On something like this, when we've had people want to really see what's going on, we have them shoot the rifle without knowing which round is which. They shoot, we give them the round and keep notes on it. Then come back several days and repeat.

Then we take a look and see what patterns came about.


As far as just taking the 22x two shot groups.....you can't really do much else except eliminate the completely bad. Small data sets are only able to weed out unacceptable data points. You can't really decide on positive data points with small samples.

 

[TheOfficeT-Rex]

You could do something like shoot the best and worst for 20 shots each. Then compare. That'll let you know how much "improvement" you have.

Which settings would be best and worst? How much improvement should I expect to see? Or is reasonable to see?

I'm not trying to get into a sample size war. I'm just trying to execute as I understood from the podcast. It sounds as if you might be referencing a different tuning test/protocol?

 

[timintx]

Popping back in with a couple questions for the collective braintrust-

I shot this test at 100 yards. I am trying to use the positive compensation tuner method. Each aimpoint is a pair fired at a different tuner setting. Blue rounds are loaded under nominal charge (slow), green ones are loaded higher (fast). There was a 60 fps difference between them.

View attachment 8266895

The conclusions I’ve drawn from this target are (please tell me where and why I’m wrong or I missed something):

• The best setting for 100 yard shooting is 3, because it has the lowest vertical spread while still having the slower round impact higher. It is tuned for this distance.
• For positive compensation at distance, setting 8 is best because it delivers the slower round higher.
• The worst of any setting is 21, because of the large vertical spread with faster rounds hitting higher.

My question:

• If I use my normal ammunition, should I be able to discern any differences between these settings at 100 yards if I fire groups?

Thanks all.

What you are looking at could be just dispersion , for that reason you should shoot a 5-6 powder charge graph first just to see what pattern you are adjusting . The two shot test is more for confirmation of tune . If you shoot a 6 powder charge graph and you are flat then your two shot test may be misleading . But if there is a good spot on the 6 shot graph you will have a better idea of what powder charge to do the two shot test . Good luck and feel free to ask any questions .

 

[TheOfficeT-Rex]

What you are looking at could be just dispersion , for that reason you should shoot a 5-6 powder charge graph first just to see what pattern you are adjusting . The two shot test is more for confirmation of tune . If you shoot a 6 powder charge graph and you are flat then your two shot test may be misleading . But if there is a good spot on the 6 shot graph you will have a better idea of what powder charge to do the two shot test . Good luck and feel free to ask any questions .

I did do a powder test prior to (albeit on a different day). The nominal charge is in the middle of a range of weights where slower charges impacted higher, although the difference is around a quarter inch.

 

[timintx]

I did do a powder test prior to (albeit on a different day). The nominal charge is in the middle of a range of weights where slower charges impacted higher, although the difference is around a quarter inch.

Ah ok , so you have a good idea of the trend before the two shot test . Just checking .I might add that if they are tracking up at all and it is only a quarter of an inch that is still good . The gun will shoot killer downrange at any distance .

 

[TheOfficeT-Rex]

Ah ok , so you have a good idea of the trend before the two shot test . Just checking .I might add that if they are tracking up at all and it is only a quarter of an inch that is still good . The gun will shoot killer downrange at any distance .

Thank you.
So would my previous conclusions about tuner settings be reasonable?
Would the minimal vertical change between loads mean the tuner is less or ineffective?

 

[timintx]

Thank you.
So would my previous conclusions about tuner settings be reasonable?
Would the minimal vertical change between loads mean the tuner is less or ineffective?

I think so now that you have told me about the graph your conclusions are most likely correct .The best confirmation would be downrange groups say at 1000 yds or so .

 

[timintx]

I think so now that you have told me about the graph your conclusions are most likely correct .The best confirmation would be downrange groups say at 1000 yds or so .

To add the tuner just moves pattern , if the pattern is consistent for a wide range of velocities then you won’t see much if a change but if your in bore timing changes big and is off of the pattern then you always have the option to turn the tuner or change powder charge to get it back in to tune .

 

[TheOfficeT-Rex]

I think so now that you have told me about the graph your conclusions are most likely correct .The best confirmation would be downrange groups say at 1000 yds or so .

Thanks Tim. I appreciate the dummy check on setting selection. I've been playing with the tuner methods off and on for over a year now and wading through the myriad of claims, methods, and target pattern interpretations has been... challenging.

 

[timintx]

Thanks Tim. I appreciate the dummy check on setting selection. I've been playing with the tuner methods off and on for over a year now and wading through the myriad of claims, methods, and target pattern interpretations has been... challenging.

Your most welcome and I hope this video and thread helps to clear up some of the misconceptions that have developed about tuners and their functions.

 

[FisherT&C]

This is a graph plotted from 3 separate ones I shot on the same day.
What's the next move?
My plan is to shoot 41.5, 42 & 42.5 for groups.
I know shooter error is in there.
I'm interested in learning more.

 

[timintx]

Studying your graph. The first (lowest) powder charge has vertical errors that are way to much . They are as much as the whole graph through out the other powder charges . I would first find the vertical error problem with your set up , I am only guessing but first shoot on bags with a concrete bench . Front and rear . Is that being done ? And is the temperature of the barrel cool at all graphs ?

 

[FisherT&C]

Studying your graph. The first (lowest) powder charge has vertical errors that are way to much . They are as much as the whole graph through out the other powder charges . I would first find the vertical error problem with your set up , I am only guessing but first shoot on bags with a concrete bench . Front and rear . Is that being done ? And is the temperature of the barrel cool at all graphs ?

I shot prone from a bipod with a rear bag. Each graph was shot 1-5 starting with a cool barrel. The barrel cooled between graphs, there is no more than a minute between 1-5 per graph. We have concrete benches, I can shoot it from a bench next time.

 

[timintx]

I shot prone from a bipod with a rear bag. Each graph was shot 1-5 starting with a cool barrel. The barrel cooled between graphs, there is no more than a minute between 1-5 per graph. We have concrete benches, I can shoot it from a bench next time.

Ok , thanks for clarifying. bags would be best on the front and rear . Bipods can give vertical dispersion especially with rubber feet . With bags on both ends you can get a more repeatable graph and and with for less vertical dispersion with one powder charge while also watching for equal velocities for a given powder charge . If they are close within a charge then you should get a more repeatable graph . If you have problems you can call me to discuss and we will get you ironed out .Good luck to you .

 

[FisherT&C]

Ok , thanks for clarifying. bags would be best on the front and rear . Bipods can give vertical dispersion especially with rubber feet . With bags on both ends you can get a more repeatable graph and and with for less vertical dispersion with one powder charge while also watching for equal velocities for a given powder charge . If they are close within a charge then you should get a more repeatable graph . If you have problems you can call me to discuss and we will get you ironed out .Good luck to you .

I appreciate you taking the time to take a look and respond.

 

[JAS-SH]

Popping back in with a couple questions for the collective braintrust-

I shot this test at 100 yards. I am trying to use the positive compensation tuner method. Each aimpoint is a pair fired at a different tuner setting. Blue rounds are loaded under nominal charge (slow), green ones are loaded higher (fast). There was a 60 fps difference between them.

View attachment 8266895

The conclusions I’ve drawn from this target are (please tell me where and why I’m wrong or I missed something):

• The best setting for 100 yard shooting is 3, because it has the lowest vertical spread while still having the slower round impact higher. It is tuned for this distance.
• For positive compensation at distance, setting 8 is best because it delivers the slower round higher.
• The worst of any setting is 21, because of the large vertical spread with faster rounds hitting higher.

My question:

• If I use my normal ammunition, should I be able to discern any differences between these settings at 100 yards if I fire groups?

Thanks all

"If I use my normal ammunition, should I be able to discern any differences between these settings at 100 yards if I fire groups?"

You should because you are shooting great.

Tuners only affect one thing - vertical, which is a life saver in most disciplines, shooting benchrest excluded because of reloading after every heat. If you set you loads in Florida and then go shoot in Wyoming they will shoot real different. That's what tuners are for...

The issue becomes "where was the barrel pointing when the shot came out". My solution to that was to use gross adjustments, fine tuning later. The idea is to see a big change in the direction that you want, and that is not intuitive. Sometimes slower shots will go high instead of low. That means that the barrel is going up fast as the shot comes out.

High means the slow bullet is still in the barrel as the barrel is going up, and vice versa.