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What new book? I only have the AB for long range shooting.
Range Report Which Published Berger BCs Are From Predictions Rather than Measurements?
- Thread starter Michael Courtney
- Start date
What new book? I only have the AB for long range shooting.
Ha! I know what you mean. Do a search on Michael Courtney and you'll see this a lot.
Rest assured your ballistics solver is solid to 800 yards at least. Physics is alive and well, despite the concerns of the good Dr. Courtney.
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Muchos gracias, my friend. Oh, I think I will buy it. I will do it right now.
It's all about that first shot. Input valid gun measurements, use a custom drag curve, run a scope calibration test, follow directions (MV cal, DSF, meaning use range that is recommended) capture target direction and crosswind at location, look down range at other indicators, bracket a wind call, shooting fundamentals, and send the damn thing.
I've been using Litz's custom drag curves for 175 SMK out of our OBRs and no issues. We have some wind sensors to play around with too and shit lines up. Unless we're calling wind within 1mph or less, we ain't hitting shit past 700 with a 1st shot.
I recommend buying a WEZ Analytics tool... It's an eye opener and makes you WANT to improve your RE and wind reading skills. That 2mph or 5% RE error will destroy you, hence why we're pushing to mounted LRFs with built in AB software, makes things a bit easier and it's faster.
I've been using Litz's custom drag curves for 175 SMK out of our OBRs and no issues. We have some wind sensors to play around with too and shit lines up. Unless we're calling wind within 1mph or less, we ain't hitting shit past 700 with a 1st shot.
I recommend buying a WEZ Analytics tool... It's an eye opener and makes you WANT to improve your RE and wind reading skills. That 2mph or 5% RE error will destroy you, hence why we're pushing to mounted LRFs with built in AB software, makes things a bit easier and it's faster.
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I don't remember getting a friend request from him or I sent one to him but in his profile you will see it. I'm like his only friend and he won't listen to me. I don't know what happened to him. When he was in CO he seemed a little normal and rarely posted on here. I read a couple of his papers and thought they were interesting but a little odd coming out of the Air Force Academy. I figured he was science professor there or something. Seriously, Michael. This is what happens when you start cross-forum bashing.
Thanks for the reference Chris.
BTW damoncali, did you update your library of BC's on your online solver to include all the new ones in this book? Feel free to do so, the more use these numbers get the better.
FYI, when I clicked on Chris's link for the book it struck me that the page was so tiny, then I figured out it was the mobile version of the page probably linked from your phone. Here's the link for viewing on a regular computer:
Modern Advancements in Long Range Shooting: Volume I
And thanks again Chris for the reference on AB Analytics and WEZ analysis. You can do some limited WEZ analysis in the free online AB solver here: Ballistics Calculator | Applied Ballistics, LLC
In this online version, most of the uncertainties are fixed, but in the AB Analytics software you can customize your rifle, ammo and shooter uncertainties to predict hit percentages for any scenario. As of today, when you purchase the AB Analytics software, you get the book "Accuracy and Precision for Long Range Shooting" for free. This book basically lays the groundwork for WEZ (Weapon Employment Zone) analysis, which is the calculation of hit % based on uncertainties.
-Bryan
Funny you mention that. I started working on an update to my code this weekend. I'll be sure to add all the new ones.
the problem with the wind calls, (and clearly it is not just me seeing it) seems to be with winds over 8MPH, usually 10 to 15MPH and especially up here. I don' t know if it is because of the altitude, does it have more of a viable effect (beyond the above discussion) or is it because we are paying a lot more attention due to the number of 1 shot only competitions here. When you have everything from Raton to CRC, to T3 all with targets beyond 800 yards with only 1 shot per target, you tend to notice these things. Pretty much everyone on the line uses a kestrel, and yes we do have some more and interesting Terrain features to deal with, but most will agree, you better off defaulting to experience than trusting the solver when it comes to wind.
As noted, I was approached unsolicited about my observations and it was stressed they dare not mention their own personal observations as the politics of the military demand you don't question it. It's taken as gospel and no data otherwise is needed.
I honestly don't think it is a coincidence, and it's not just a case of a bad wind call, when working the results backwards, that 30% error rate is spot on and being observed by too many to dismiss. I know it is not BC related, but it is inside the PM Solvers over any other. Being realistic, ColdBore and FFS are around 5%, well the other are definitely closer to 30% off. Here is the deal, having just shot FLA this weekend, the wind is barely a factor compared to the ranges here in CO. We average 12MPH and down there, even at 800 yards you might use .5 Mils to hit, if that, more like .3 so the odds of seeing it on the East Coast with light winds is close to Nil.... I understand, on days when our gusts are easily 6MPH by themselves, but on days with a consistent wind... you cant tell me I can group sub MOA at 800 yards and it's a bad wind call. The bullet is not being effected that much.
Here is a good example I have recorded,
130gr Berger VLD Load @ 2950fps out of a 21" AW the group was shot at 800 yards with a 6MPH recorded wind
The groups sizes is solid, and the measurement to the target says I would need .3 Mils of wind to hit center ...
if you put the details into JBM which I have done, it says I need .7 Mils of wind or just shy of 20" of drift. There is the target with the scoring rings and I held center. That is clearly not 20" of drift ... that is the point I am making I went downrange and recorded .3 was needed to hit center, the computer says .7
I personally believe and others who are paying attention believe there is an issue inside the solver on how it figures this ... not pointing fingers just asking how do we tighten up this part of the equation. After all it should be as simple as "Cause and Effect" of the Wind blows "X" the solution is "Y" if we hit variations downrange because of Terrain, I get that, but on a manicured range with very little obstacles, the variations are not great. Which the Group itself can attest too, I did not change my hold from Shot 1 to Shot 5.
As noted, I was approached unsolicited about my observations and it was stressed they dare not mention their own personal observations as the politics of the military demand you don't question it. It's taken as gospel and no data otherwise is needed.
I honestly don't think it is a coincidence, and it's not just a case of a bad wind call, when working the results backwards, that 30% error rate is spot on and being observed by too many to dismiss. I know it is not BC related, but it is inside the PM Solvers over any other. Being realistic, ColdBore and FFS are around 5%, well the other are definitely closer to 30% off. Here is the deal, having just shot FLA this weekend, the wind is barely a factor compared to the ranges here in CO. We average 12MPH and down there, even at 800 yards you might use .5 Mils to hit, if that, more like .3 so the odds of seeing it on the East Coast with light winds is close to Nil.... I understand, on days when our gusts are easily 6MPH by themselves, but on days with a consistent wind... you cant tell me I can group sub MOA at 800 yards and it's a bad wind call. The bullet is not being effected that much.
Here is a good example I have recorded,
130gr Berger VLD Load @ 2950fps out of a 21" AW the group was shot at 800 yards with a 6MPH recorded wind
The groups sizes is solid, and the measurement to the target says I would need .3 Mils of wind to hit center ...
if you put the details into JBM which I have done, it says I need .7 Mils of wind or just shy of 20" of drift. There is the target with the scoring rings and I held center. That is clearly not 20" of drift ... that is the point I am making I went downrange and recorded .3 was needed to hit center, the computer says .7
I personally believe and others who are paying attention believe there is an issue inside the solver on how it figures this ... not pointing fingers just asking how do we tighten up this part of the equation. After all it should be as simple as "Cause and Effect" of the Wind blows "X" the solution is "Y" if we hit variations downrange because of Terrain, I get that, but on a manicured range with very little obstacles, the variations are not great. Which the Group itself can attest too, I did not change my hold from Shot 1 to Shot 5.
Frank,
My advice is to take Nick up on his offer to go come out and shoot with our wind sensor array (WSA).
Like you, I use a computer for elevation but make wind calls based on judgment in my shooting comps. Not because I don't believe the solvers wind calcs, but because we're not allowed to have electronics on the line, and because wind is so fluid and our shots so frequent, that it just works out that shooters can combine wind reading with 'chasing the spotter' to keep shots centered pretty well without tools.
While shooting under the WSA I was able to keep my group round and centered on a ~36" steel plate at 1 mile with the 338 (TRG-42). To the best of my recollection, I was hitting about 1/4 to 1/2 of the shots, with as many missing for elevation as windage. This was shooting over some terrain (Thunder Valley Precision). With conventional wind indicators, I'm certain my calls and shots would have resulted in a much wider group as compared to shooting under the WSA.
For our purposes which were experimental, I would stay on target with Nick and Dan watching the computer and telling me when the wind hold settled on a particular value and I would shoot that hold. It was amazing to me how much the wind holds changed from the WSA calculations when you could look down range at the same time and 'see' no changes.
I'm not denying your experiences, only saying that it's an eye opener to get onto a range instrumented with numerous anemometers. Might be something you'd be interested in for your range and classes.
-Bryan
My advice is to take Nick up on his offer to go come out and shoot with our wind sensor array (WSA).
Like you, I use a computer for elevation but make wind calls based on judgment in my shooting comps. Not because I don't believe the solvers wind calcs, but because we're not allowed to have electronics on the line, and because wind is so fluid and our shots so frequent, that it just works out that shooters can combine wind reading with 'chasing the spotter' to keep shots centered pretty well without tools.
While shooting under the WSA I was able to keep my group round and centered on a ~36" steel plate at 1 mile with the 338 (TRG-42). To the best of my recollection, I was hitting about 1/4 to 1/2 of the shots, with as many missing for elevation as windage. This was shooting over some terrain (Thunder Valley Precision). With conventional wind indicators, I'm certain my calls and shots would have resulted in a much wider group as compared to shooting under the WSA.
For our purposes which were experimental, I would stay on target with Nick and Dan watching the computer and telling me when the wind hold settled on a particular value and I would shoot that hold. It was amazing to me how much the wind holds changed from the WSA calculations when you could look down range at the same time and 'see' no changes.
I'm not denying your experiences, only saying that it's an eye opener to get onto a range instrumented with numerous anemometers. Might be something you'd be interested in for your range and classes.
-Bryan
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I'm at 3600' and usually use the 30% rule that I judged based on trail and error over time. It is interesting. It had me scratching me head for a long time and did some serious damage. Things just weren't adding up to dry shit. Wind is usually 10-15 MPH. Good day 5-10. Dawn and early morning is usually calm and the apps predict well. In the past I tended to overestimate the wind and then apps came along and appear to do the same thing. It took my a while to figure this out. I just thought, oh well the winds are squirrely downrange so I'm going to subtract 1/3 of the wind speed and see what I get. Then I started doing that a lot and noticed an improvement. Not scientific but willing to share.
The beauty of science is that it doesn't matter what anyone believes, the next step is the same either way - measure the biggest uncertainty and see what happens. In Lowlight's case, even with a very skilled shooter under some pretty specific conditions, the biggest uncertainty is still the wind measurement. Until that is nailed down, we're speculating as to what exactly is being observed. The theory points to bad wind calls. But that doesn't always make it so.
We've seen the same thing. Thanks for sharing.
Quick question relating to this whole thing: when using the AB app, if I choose a bullet with (Litz) next to it, will the solver use the custom curve for this bullet or does it just use the measured corrected BC? Can't tell on the app (iPhone) how to specifically tell it to use the curve and not just the BC. Maybe this feature is not available on the iPhone version. I need to get the software that comes as a package with the AB book, currently I just have the eBook so I cannot comment on if curves can be chosen in that. I ask this partially also because I am planning to get the kestrel with AB for a nice compact package and so input on the curves vs corrected BC with the kestrel is also welcomed. Thanks!
Like I said before...when Courtney actually creates or produces something better, THEN we will take notice. It is much easier to tear down someone else's work than it is to produce a working solution to a real world problem, or to physically execute that solution. When I was at the Zoo (the AF Academy), there were all kinds of "experts" on air warfare theory that never set foot on a flightline. As an aero major there, I became well acquainted with these types with no practical experience that will argue til they are blue in the face on an esoteric point and never understand the broader picture because they think but never "do."
That is what is happening here. He has a bone to pick and thinks he has caught Berger in something and the big "reveal" was going to make him a hero as we all gasp in horror at their "lies". Because he has never involved himself in this world, he doesn't understand how much Berger, and Bryan Litz specifically, has done for the long range community, and thus our appreciation. They have helped us get results, he hasn't. Nothing personal, its just the way it is. Doesn't have to stay that way, and I hope Courtney produces a workable solution that improves our ability to produce first round hits. Is it the model, our wind calls, or both would be a good place to start.
There is nothing wrong with pointing out that crosswind prediction models could be more accurate. Well no shit, of course they could. Are we supposed to be impressed at this obvious fact? Long Range competitive shooters, fighter pilots, snipers and sniper instructors like LL, and other type A personalities are far more impressed with solutions than they are criticism. Do the work, solve a problem, and the market will let you know how well you have done, because the type of people I mention above care about results not jawing.
In other words, be part of the solution, and you wont have to quote a resume nobody cares about to get recognized, it will come with the useable results you produce. This is the world we live in; nobody cared what I KNEW as a fighter pilot, they only cared about what I could use that knowledge to DO. Thats the way it should be when your job is to put steel on target, whether it is 175grains or 2000lb at a time.
Courtney - Get us a better wind solution, or better trajectory predictions, and people will sing your praises as they should. Trying to whip up scorn on people who have put their money where their mouth is and succeeded is only going to blowback on you if you offer nothing better. Being a help, not a hindrance, and teamwork have solved a lot of problems.
"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly; who errs, who comes short again and again, because there is no effort without error and shortcoming; but who does actually strive to do the deeds; who knows great enthusiasms, the great devotions; who spends himself in a worthy cause; who at the best knows in the end the triumph of high achievement, and who at the worst, if he fails, at least fails while daring greatly, so that his place shall never be with those cold and timid souls who neither know victory nor defeat."
--Theodore Roosevelt
That is what is happening here. He has a bone to pick and thinks he has caught Berger in something and the big "reveal" was going to make him a hero as we all gasp in horror at their "lies". Because he has never involved himself in this world, he doesn't understand how much Berger, and Bryan Litz specifically, has done for the long range community, and thus our appreciation. They have helped us get results, he hasn't. Nothing personal, its just the way it is. Doesn't have to stay that way, and I hope Courtney produces a workable solution that improves our ability to produce first round hits. Is it the model, our wind calls, or both would be a good place to start.
There is nothing wrong with pointing out that crosswind prediction models could be more accurate. Well no shit, of course they could. Are we supposed to be impressed at this obvious fact? Long Range competitive shooters, fighter pilots, snipers and sniper instructors like LL, and other type A personalities are far more impressed with solutions than they are criticism. Do the work, solve a problem, and the market will let you know how well you have done, because the type of people I mention above care about results not jawing.
In other words, be part of the solution, and you wont have to quote a resume nobody cares about to get recognized, it will come with the useable results you produce. This is the world we live in; nobody cared what I KNEW as a fighter pilot, they only cared about what I could use that knowledge to DO. Thats the way it should be when your job is to put steel on target, whether it is 175grains or 2000lb at a time.
Courtney - Get us a better wind solution, or better trajectory predictions, and people will sing your praises as they should. Trying to whip up scorn on people who have put their money where their mouth is and succeeded is only going to blowback on you if you offer nothing better. Being a help, not a hindrance, and teamwork have solved a lot of problems.
"It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly; who errs, who comes short again and again, because there is no effort without error and shortcoming; but who does actually strive to do the deeds; who knows great enthusiasms, the great devotions; who spends himself in a worthy cause; who at the best knows in the end the triumph of high achievement, and who at the worst, if he fails, at least fails while daring greatly, so that his place shall never be with those cold and timid souls who neither know victory nor defeat."
--Theodore Roosevelt
Awesome quotes!
Yours perfectly describes what's happening here and I couldn't agree more.
I think I'm going to print and frame the Roosevelt quote.
Nailed it man. Great quote and great perspective. As a community we should be working together to put first round hits on target. That's all that matters in this business.
That's the problem with the intellectuals and professors who never leave "academia". They don't work in the arena of market forces and don't understand it. They don't solve problems, they create more problems to perpetually study so they can write more grants to use the money of those that are actually putting people to work and using knowledge in a PRACTICAL way.
Since earning my PhD almost 20 years ago, I've spent 10 years in academia (faculty jobs) and 19 years subject to the same market forces as everyone else. Almost all of my colleagues and co-authors have also spent the majority of their careers working for private companies with a few years serving as University faculty to broaden perspectives. Most of our research funding is from private sources, solving problems closely connected with private companies ability to stay in business. We hardly write any grants. Parties come to us with money and ask us to solve their problem.
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Good thread.
That particular Teddy quote is framed and hangs in my reloading room.
That particular Teddy quote is framed and hangs in my reloading room.
My favorite TR quote:
"We cannot afford to differ on the question of honesty if we expect our republic permanently to endure. Honesty is not so much a credit as an absolute prerequisite to efficient service to the public. Unless a man is honest, we have no right to keep him in public life; it matters not how brilliant his capacity."
"We cannot afford to differ on the question of honesty if we expect our republic permanently to endure. Honesty is not so much a credit as an absolute prerequisite to efficient service to the public. Unless a man is honest, we have no right to keep him in public life; it matters not how brilliant his capacity."
Michael,
At this point, it's no longer a question of honesty.
Berger and I have been forthcoming in all of your questions.
There's nothing more to discuss.
At this point, it's a matter of when you'll stop trying to piss in shooters' ears and tell them it's raining.
At this point, it's no longer a question of honesty.
Berger and I have been forthcoming in all of your questions.
There's nothing more to discuss.
At this point, it's a matter of when you'll stop trying to piss in shooters' ears and tell them it's raining.
I appreciate that.
I wish you had been a bit more clear with which varmint and which flat base match bullets were actually measured.
Berger has fabulously accurate flat base bullets, so project contributors nearly always peruse the Berger catalog when designing a new experiment or working on a new project. Don Miller always wanted us to do an experiment linking stability and accuracy, but my concern was that confounding factors would bugger up the works and mask stability effects in the noise. We settled on the need to do the experiment either at night or indoors and to use a group of barrels in a randomized way to get good statistics and separate the signal from the noise.
We also intend to circle back around to the wind drift projects. For various reasons, these experiments are easier at shorter ranges with lower BC bullets. If MPM has problems predicting wind drift at shorter ranges with low BC bullets, it won't work any better at 1000 yards with high BC bullets. Shorter range eliminates uncertainties in the drag curve between M1.0 and M1.5. Shorter range reduces other confounding effects and sources of inaccuracy. Shorter range allows for more uniform wind fields and improved ability to quantify wind fields more accurately with a given capital investment. But when picking lower BC bullets for an experimental design, knowing the BC is important, and Berger discontinued one of the two we had actually measured.
Here's a tip - isolate the variables you want to test. You can't complain that point mass is bad because the drag data isn't good enough, and then test it in the velocity region where we are most certain about drag. Another tip - do some work with the software (write a solver) before you head to the range. It will give you some clarity into what the point mass method is and isn't. You're missing something fundamental here. F=MA isn't the problem. It's drag, and you're going out of your way to test the F=MA part.
Maybe I missed it.... But does this Courtney fellow actually shoot comps or recreational. Does he shoot LR or ELR? Or does he just "experiment " for ballistic data??
Our first hint that there might be a BC problem with the Bergers was when the 115 VLD failed to expand on a long range deer. At the time, the advertised BC was 0.523. We started measuring BCs shortly after this because we wanted to know the impact velocity more accurately to understand terminal performance at long range. We later measured the BC of that bullet as 0.419, which provided a good explanation for the failure to expand. Berger later adjusted that BC downward to 0.466 and attributed the lower BC we measured to a worn die because when we checked, the dimensions of the bullets we had were off. When Berger sent us new bullets (new die) our BC measurements agreed with theirs.
I've also shot a lot of varmints over the years. Both terminal velocity and wind drift are big issues with varmint shooting. Most of my competitive shooting has been long range precision rifle - shooting prairie dog and similar steel targets out to 700 yards or so. In addition, I've shot a small number of long range benchrest matches. My colleagues and co-authors shoot long range precision rifle, benchrest, and F-Class and I often serve as coach/spotter for them in these rather than competing myself.
The dope was checked by shooting at long range, and I did notice the need to adjust the elevation more than expected. I simply made a chart of the measured elevations actually needed at the ranges at which shots were expected. Perhaps there was a lack of due diligence on my part, but at that point I still believed the published BC and attributed the need for extra elevation to some other factor: imperfect scope tracking, temperature dependent muzzle velocity, imperfect range determination, imperfect environmentals, etc. We'd done due diligence to ensure hitting the target, but not to determine why extra elevation was needed.
It was not until we started measuring BCs soon after that we bought some Kestrels and became much more careful about other details like checking scope elevations adjustments for accuracy and repeatability independently of long range sighting adjustments. We later learned that the specific scope has excellent accuracy and repeatability in its elevation and windage adjustments.
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Your CV on your website says you earned your PhD in 1995. Your website also states you are a mathematics professor. Surely you can do subtraction. Seems like 2014 - 1995 = 19 years.
And you were saying something about Berger not being honest? What the fuck, dude?
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Typo, should have been "almost 20 years ago." Sorry about that.
OK Professor, before you start thinking you are the equal of a guy like Bryan, lets see you start answering some of the questions you keep spouting off. I am starting to think you ain't got a clue and would not know where to buy one if you had a shoe box full of dollar bills.
A scientific/engineering discussion should focus on the facts rather than the personalities.
The above questions were posed to the author of published material because they concern details that only the author (or others with inside information) would know. Those not privy to the original data or the detailed methods by which the original data was transformed into the published material would only be guessing at the answers to the above questions.
I'd be happy to answer the above questions for any of the drag curves our group has published. You can rest assured that if we publish a BC or Cd at a given velocity or Mach number, that we've actually measured the BC or Cd at the specified velocity or Mach number and we're not extrapolating from a much narrower range. For example, in the attached figure, we actually measured the Cds over a range from M1.36 to M2.98. The uncertainty in Cd at each Mach number is about 1%, but at one point is closer to 2% and shown with error bars.
Attachments
This is a good example, let's consider it for a moment.
So you measured the drag of a bullet at Mach 1.36 (~1517 fps), probably over 100 or 200 yards.
My question is; what barrel twist did you use to test the bullet at this speed?
As a bullet slows down on a long range trajectory, its spin rate doesn't decay as fast as it's forward velocity, which means that if it was turning 1:9" @3100 fps from the muzzle, by the time it's lost 1/2 it's velocity, it will be spinning at a rate much faster than 1:9", probably closer to 1:6".
So my question to you is, did you fire your low velocity data points from a faster twist barrel than your high velocity data points? If not, then the data point is not representative of the bullets actual stability condition at that speed on a real long range shot.
Another question; didn't you publish on the effects of tip off rate affecting BC? If you fire the bullet at 1517 fps MV and you gather that data point where there's a 'tip-off' rate which reduces BC, then, again, it won't be flying as it really does on a long range shot.
And now to answer your question.
The reason my data points appear to be clustered tightly together is because they represent the center of the speed range tested. Since I test over long range, a shot with a MV of 3200 fps which slows to 1600 fps, will have a midpoint of ~M2.15. So that's where the data point would sit. My data points appear clustered on the graph, but my measurements are a more accurate representation of the bullets actual drag at long range.
This is another example of you dwelling on the minutia in order to twist the facts. Yes it's a fact that you tested a data point at M1.36. It's also a fact that that data point doesn't represent the bullets actual drag at that speed on a real long range shot.
I'm going to go out on a limb here and say that actual shooters actually care about drag models which actually put them on target at long range more so than they care about where your points are on a graph and why you say your way is better.
You'd like that wouldn't you. Except you loose the scientific/engineering points as well because your 'facts' are not in alignment with what shooters experience (or they're abstract and irrelevant). I still can't decide if you're twisting of all these facts is deliberate, or if you really just don't get it. It's been suggested that you just have an overwhelming appetite for attention, good or bad doesn't matter. If that's the case, you can make your therapy check out to Snipers Hide as a contribution for helping you with your mental issues.
One thing I am sure of is that shooters appreciate information that helps them hit targets. I don't ever recall you EVER providing any such information. What I do see a lot of from you is criticism of those who do.
As always, you keep doing what you do, and I'll keep doing what I do.
-Bryan
For those jumping over from the other Berger thread, allow me to save you some reading and summarize:
Michael: Berger says all their BC's are measured. They're lying.
Berger: Yeah, sorry about that. We misspoke. Only the BCs for bullets where people actually are about BCs are measured. The others are calculated.
Michael: You owe us an apology.
Everyone Else: Whatever. They're great bullets and nobody cares about flat base BC's. Thanks, Berger! You rock!
Michael: Bryan Litz is a liar. And the point mass method is wrong.
... much discussion ...
Some dude: Whoa! Child sacrifice? Didn't see that coming.
Michael: Bryan is a liar. I am the champion of the consumer.
Bryan: Um, your papers are all wrong and look like they've been written by students on a Friday afternoon. Nobody believes you.
Michael: Please, stick to the facts.
Michael: Berger says all their BC's are measured. They're lying.
Berger: Yeah, sorry about that. We misspoke. Only the BCs for bullets where people actually are about BCs are measured. The others are calculated.
Michael: You owe us an apology.
Everyone Else: Whatever. They're great bullets and nobody cares about flat base BC's. Thanks, Berger! You rock!
Michael: Bryan Litz is a liar. And the point mass method is wrong.
... much discussion ...
Some dude: Whoa! Child sacrifice? Didn't see that coming.
Michael: Bryan is a liar. I am the champion of the consumer.
Bryan: Um, your papers are all wrong and look like they've been written by students on a Friday afternoon. Nobody believes you.
Michael: Please, stick to the facts.
Thank you for clarifying the issues from your book that I had asked about earlier.
The stability was over 1.5 for all the data points in the attached figure. Sierra has done some very convincing work showing the consistency of BCs (and drag coefficients) for different twist rates, as long as the bullet is well stabilized. One should consider section 2.5 of the 5th edition of the Sierra Reloading Manual before suggesting that BC depends on twist rate for well stabilized bullets. For example, Figure 2.5-2 (Sierra 5th edition) shows BCs are consistent for the 69 grain SMK in barrels with 1 in 7", 1 in 8", 1 in 9", and 1 in 10" twist rates. There is only a reduction in BC for the 1 in 12" twist rate for that bullet under their test conditions.
Further, Figure 2.5-3 (Sierra 5th Edition) shows BCs are consistent for the 190 grain (.308) SMK in barrels with 1 in 8", 1 in 9", 1 in 10", and 1 in 11", with only a loss of BC (drag rise) for 1 in 12" and 1 in 14" twist rates under their test conditions.
Consequently, there is no experimental support for the suggestion that bullets that leave the barrel at Sg > 1.5 are experiencing more drag than they would if fired with faster twist rates (higher stability).
The bullets were all fired from the same barrel, which was fine, because the stability was above 1.5 for all the test shots.
Our earlier published paper concerned the effects of pitch and yaw in drag coefficients rather than BC. The effect is small (< 2%) in the bullets we used, requires very careful measurements to see, and has mostly disappeared after the first 50 yards.
Our shots with the smallest powder charges (low Mach numbers) have no discernable effects of pitch and yaw. The pressures at the base of the bullet as it exits the barrel from 6 grains of Blue Dot are much smaller than with a full power load, so tip off effects are too small to see. In the attached figure, the Cds were determined over 100 yards, so the effects of pitch and yaw might be as large as 1% at the higher Mach numbers, but are much smaller at M1.36.
One needs longer bullets with larger tip off rates to see more significant effects on drag.
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I did not mean to imply that my "way is better" only that determining drag coefficients over the whole range of Mach numbers is more meaningful than extrapolating the curve from a small number of points. Isn't this the point of having "custom drag curves" that some in ballistics are now advocating.
Further, being able to accurately predict the impact velocity (in addition to drop) is essential for ensuring terminal performance. For example, many solid copper bullets (as mandated by CA) have higher expansion thresholds than lead core hunting bullets. For example, using our measured BC for the 150 grain Nosler E-Tip (.308) suggests a maximum expansion range of 350 yards using their Nosler's threshold of 1800 fps. Using Nosler's BC suggests expansion out to 500 yards.
One only needs to shoot paper out to 500 yards (or whatever your max shot range is) to correct for drop issues related to inaccurate BCs. The low impact velocity and failure to expand will likely go unnoticed until a hunt is ruined.
Mr. Courtney, with all due respect, I think it is you who owes the apology to Brian. As others have said , Berger is the tier one bullet maker right now and IMHO has revolutionized not only the bullet industry itself , but the sport as a whole. As busy as Mr. Litz is, he still takes the time to consult with shooters in forums such as this one. I for one can see that while trying to be polite in your responses are beginning to piss Mr. Litz off. I can't blame him. It seems like a political attack hidden behind some kind of agenda.
I'm telling you this because if you continue to "call out" Brian in the subtle ways you are , your going to make the worst enemies you could imagine.... Snipers Hide Members. It is well known that this is the most respected Shooting Forum on the net and some members of this forum belong to and own some of the most exclusive and prominent clubs and businesses in the industry. I respect the fact that everyone has an opinion and yours is a little different than the rest given your "expertise" but if you plan on having the " street cred" for future publications that people will take seriously and not as a one upper to Brian , I would highly advise dropping this "subtle" attack on The Poster Boy of the Shooting World.
Rant over
I'm telling you this because if you continue to "call out" Brian in the subtle ways you are , your going to make the worst enemies you could imagine.... Snipers Hide Members. It is well known that this is the most respected Shooting Forum on the net and some members of this forum belong to and own some of the most exclusive and prominent clubs and businesses in the industry. I respect the fact that everyone has an opinion and yours is a little different than the rest given your "expertise" but if you plan on having the " street cred" for future publications that people will take seriously and not as a one upper to Brian , I would highly advise dropping this "subtle" attack on The Poster Boy of the Shooting World.
Rant over
OK, here we go again.
You make this claim several times, but the truth is, you don't know what the stability level was of these bullets. The Miller formula (and its variants) are based around 2800 fps, with a correction factor that's good for small variations in Mach. The velocity correction is way off condition at a MV of M1.36. Even if you used a more sophisticated model like PRODAS, aero-prediction codes are notoriously bad at estimating overturning moment coefficients near transonic speeds.
So although the math suggests stability, the truth is, you just don't know that.
To clarify for the readers how our methods of drag measurement differ:
You're way: determine specific points of drag over 100 or 200 yard increments by downloading a bullet to transonic MV and shooting it in an unknown stability condition to "gather more points".
My way: load the bullet to it's typical MV and shoot it with adequate stability and determine it's BC by measuring TOF over actual long range flight.
Not only is my method more representative of how bullets are actually fired, but it also has less uncertainty since measurements are being made over greater distance.
And academics aside, the results of my method are field proven. The results of your method are not even in use.
Mike, I think you've worn out this particular topic. You seem to get some favorable attention for a short period of time with a fresh group of people who don't know you yet, but that ships sailed.
-Bryan
You make this claim several times, but the truth is, you don't know what the stability level was of these bullets. The Miller formula (and its variants) are based around 2800 fps, with a correction factor that's good for small variations in Mach. The velocity correction is way off condition at a MV of M1.36. Even if you used a more sophisticated model like PRODAS, aero-prediction codes are notoriously bad at estimating overturning moment coefficients near transonic speeds.
So although the math suggests stability, the truth is, you just don't know that.
To clarify for the readers how our methods of drag measurement differ:
You're way: determine specific points of drag over 100 or 200 yard increments by downloading a bullet to transonic MV and shooting it in an unknown stability condition to "gather more points".
My way: load the bullet to it's typical MV and shoot it with adequate stability and determine it's BC by measuring TOF over actual long range flight.
Not only is my method more representative of how bullets are actually fired, but it also has less uncertainty since measurements are being made over greater distance.
And academics aside, the results of my method are field proven. The results of your method are not even in use.
Mike, I think you've worn out this particular topic. You seem to get some favorable attention for a short period of time with a fresh group of people who don't know you yet, but that ships sailed.
-Bryan
My apologies Bryan. Damn spell check got me....
D
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I got your new book, Bryan. A lot of new useful information. Good work and glad to see you qualifed your SMK 168 statement from your first book. More better.!
Quoted for emphasis.
We've validated the stability formulas by turning down the stability at low Mach numbers. The bullets tumble when the appropriate formula predicts SG < 1.0 and do not tumble for formula predictions that SG > 1.0.
It's not just the formulas suggesting stability, the experiments confirm it.
I hope you can forgive the poor video quality, but I have attached a frame of a high speed video showing a 55 TTSX beginning to tumble near M1.2, just where the stability formula predicted it would for the given twist rate and environmental conditions.
In our testing of armor and terminal ballistics at low Mach numbers, we've found the predictions of our stability formulas very reliable (within 5%) down to M0.8 and we've shot a lot of bullets at M0.8 to M1.5.
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More twisted facts.
We KNOW bullets tumble for SG lower than 1, and not for SG greater than 1. That's actually a definition.
What I'm questioning is the validity of your data points which are created in stability conditions which are different from what the bullet actually flies with on a long range shot.
And why did you choose this one point to respond to and ignore the rest?
We KNOW bullets tumble for SG lower than 1, and not for SG greater than 1. That's actually a definition.
What I'm questioning is the validity of your data points which are created in stability conditions which are different from what the bullet actually flies with on a long range shot.
And why did you choose this one point to respond to and ignore the rest?
You seem to be challenging the validity of the Miller stability formulas (which we have experimentally verified) as well as the long established results from Sierra that BC is independent of stability for well-stabilized bullets.
This is a more interesting technical discussion than the other rabbit trails. I want to see if you have any real data to support your claims.
I accept that the Sg of a bullet that was fired at 2800 fps and slowed to 1500 fps is higher than one that is fired at 1500 fps at the muzzle.
But if the Sg > 1.5 at the muzzle, there is no reason to believe the downrange bullet (Sg is higher) has a different BC because of the higher Sg. Damping of pitch and yaw may have raised its BC 1-2%, depending on the tip off and bullet length.
I've seen you define 'rabbit trails' in the past as subjects you prefer not to discuss anymore because someone called you out on your BS and you would rather not talk about that anymore.
So, again, it's the old: On to child sacrifice! routine again.
Courtney vs. the heathens - The Tech
Seriously?
My most recent experiments on this topic are published in Modern Advancements in Long Range Shooting.
I wouldn't expect you to be familiar with this work though, it hasn't been approved for release by your peers, or 'peeps' as you call them.
http://www.bergerbullets.com/twist-rate-calculator/
Your stability calculator suggests bullets may have a reduced BC for SG < 1.5, but that the BC is constant for SG >= 1.5.
Is there data in your book contradicting your stability calculator?
I was under the impression that your stability calculator incorporated all the related findings supported by data in the book.
Yes or No? Do you have data showing BC losses for SG values above 1.5?
If so, when do you plan to update the stability calculator to reflect these findings?
Mikey, I don't answer to you.
You claim to be a ballistics expert who's "published more than anyone else...". How about you try READING some the published works by others on the subject before you question their conclusions. My study of transonic stability and drag is based on careful and extensive live fire testing. The Berger stability/BC calculator that you linked above is one example of a useful result of that work. I know you have a big problem with 'useful' things, but you'll just have to live with this one.
As for your attempts to try and twist my words into something contradictory... I'm not going to continue spoon feeding you on internet forums when my work is published in black and white.
Read it, and if you need help understanding anything, ask.
If you'd rather launch another public criticism (more your style), go for it. But know that you're eroding the credibility of BTG with each post you make.
From a business perspective, that's actually good for me. But honestly I'm concerned about how your damaging the credibility of everyone else in your group. I don't know them, but they might be hard workers and maybe they deserve better representation than you.
The hole seems deep enough to bury you now, you can stop digging.
I think I'll buy a box of Berger bullets for every post the guy makes trying to nitpick your work
I do have a question though, on the calculator, it shows the 215 Hybrid .308 out of a 10 twist at 2940, just above sea level, as marginally stable. However other online calculators (jbm) show stability well over 1.5. Could the data for the bullet be wrong in the calculator?Similar threads
