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Scientific differences between Applied Ballistics and Horus Kestrel.

Christopher Rance

CR2 Shooting Solutions
Full Member
Minuteman
First and foremost this is a statement on the scientific differences of the two models. In no way is this a negative statement on Horus or the creators of Atrag. This statement isn't from Kestrel.

As mentioned in previous posts by Frank, generally any well written solver should produce an accurate solution as long as the correct inputs are given.

Obviously there are uncertainties in long range shooting, with wind being the greatest one. Learning to accurately assess wind speed and direction can improve hit % dramatically. Other uncertainties such as MV deviation, range ect will also effect your shooting. The best way to combat this is to use accurate inputs and always improve your fundamentals in shooting, wind calls and RE.


From AB team;
The AB solver coupled with the Litz-measured drag curves provides accurate solutions to ELR without the typical "tweaking" that has been previously necessary to get rounds on target. Several of these features are not specifically mentioned in press releases but in working with the AB team, I have come to learn that there are several advanced features. One of them includes air density compensation for high angle shooting. At extreme angles, this can become a real issue. Additionally, when dealing with high crosswinds, aerodynamic jump also causes the elevation to change as well. All of these items are included within the AB solver but may be be explicitly called out.

As a result, by using the Litz-measured drag curves and when using the AB Kestrel and inputting accurate sensor and wind data, the elevation is accurate to extreme long range. Even though most solvers ignore such things, at ELR each of them adds up to a significant enough influence that you are likely to be off target. When engaging steel or on a range, this may not matter, but in a military scenario, this could be very different. Since there is no distinction on the AB units for the military and the civilian versions, the AB device has all of the capability that the military is using as well. Thus, increasing the standoff range of the currently deployed 0.308" weapons is a must and the AB solver allows that to happen.

While many users may not be aware of the internal workings of the ballistics solvers, there are other important distinctions. One such item is the usage of truing the ballistic coefficient. The ATRAG units handle this by modifying the ballistic coefficient (usually by lowering it at longer ranges) as a function of range. However, this leads to a modified time of flight and thus in turn, a wind deflection that is greater than expected. With the usage of the DSF calibration that the AB solver uses, the wind deflection is unchanged by the DSF modification. I know that the AB team has conducted many experiments and data collections that show that this is the better way to go and provides more accurate wind correction at long range as well.
 
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One of them includes air density compensation for high angle shooting. At extreme angles, this can become a real issue

While nice to know, this is a feature most people will never utilize or even have a need for.

Since there is no distinction on the AB units for the military and the civilian versions, the AB device has all of the capability that the military is using as well

So does this mean that the publicly available AB version has the loophole capability enabled or that the loophole capability isn't available on the AB model period?


Cutting out all the marketing chatter from the AB statement above, it sounds like the biggest difference between the two is not having to true your data due to using the Litz curves. Please correct me if I am wrong or have missed something.
 
also IIRC Litz defines ELR as for a cartridge up to the point of transonic - at least in his book. I guess ELR is defined differently by different people - I think many define it by distance - ie. 2000 yards or 1500 yards. Since the statements about these different devices talk about ELR, its likely a good idea to understand what they mean.
 
Does it include calculations for the gravitational attraction of the moon phase and orbital position of the moon relative to the earths orbit around the sun, and the ocean mass relative to tidal flow? I missed my last shot because I input waning - it was waxing.
 
The AB model doesn't have the loophole feature, that is only on the Mil Horus model.

ELR is defined by where the bullet enters transonic/subsonic realm of flight, so every bullet is different.

"When using the custom drag curves, the notion of having a BC referenced against a standard model drag curve such as the G1 or G7 no longer applies. As a result, we have created a scaling that applied to both the custom curves and the standard curves and does not act on the BC. It acts on the scaling of the drop and as a result, we called it the drop scale factor. "

"The DSF is also a very simply concept that almost anyone can understand. Let's show an example...

- An operator shoots to 1000 meters and the predicted drop is 10 mils.
- The operator observes that the actual drop is 11 mils
- The operator enters this into the DSF calibration screen and the computed DSF will be 1.100 at the Mach at which the bullet is at when hitting 1000 meters.

The math there is simple and I am sure you just picked up on it... the predicted drop was 10 mils. The observed drop was 11 mils. Therefore, there is 11/10 mils of drop or 1.100 or 10% more drop. So, when shooting to that point, the drop is scaled by 10% more (multiplied by 1.1). That's pretty simple and intuitive and should be easy for most people to understand.
 
The AB model doesn't have the loophole feature, that is only on the Mil Horus model.

So there is no Mil AB version. So making a statement that civvy AB users are getting the same as a Mil unit is misleading as there IS NO Mil version. I fail to see how any of this "increases the stand off of the 308". 308 ballistics and standoff are pretty well documented and known, using AB doesn't all of a sudden increase or change the law of physics.That whole statement is marketing hype IMO.



"When using the custom drag curves, the notion of having a BC referenced against a standard model drag curve such as the G1 or G7 no longer applies. As a result, we have created a scaling that applied to both the custom curves and the standard curves and does not act on the BC. It acts on the scaling of the drop and as a result, we called it the drop scale factor. "

"The DSF is also a very simply concept that almost anyone can understand. Let's show an example...

- An operator shoots to 1000 meters and the predicted drop is 10 mils.
- The operator observes that the actual drop is 11 mils
- The operator enters this into the DSF calibration screen and the computed DSF will be 1.100 at the Mach at which the bullet is at when hitting 1000 meters.

The math there is simple and I am sure you just picked up on it... the predicted drop was 10 mils. The observed drop was 11 mils. Therefore, there is 11/10 mils of drop or 1.100 or 10% more drop. So, when shooting to that point, the drop is scaled by 10% more (multiplied by 1.1). That's pretty simple and intuitive and should be easy for most people to understand.

You know what that sounds like to me? TRUING. It may use a different approach to obtain the same ends but call it what it is and that is truing. DSF or what ever they want to call it cannot change the laws of physics and so far the "scientific" explanation given here is nothing more than marketing hype IMO. And I get that, they are trying to sell their product. But I also think they are trying to convince current kestrel ATRAG users to buy the same kestrel with different software in it with fancy packaging/word speak and the assumption that they are getting something markedly "better" than what they currently have. Unfortunately, no one has provided a simple solution out put comparison between the two units let a lone a truly scientific one.

The way I see this, and I may be wrong, is that Kestrel has decided to move away from Horus software and team with AB for what ever reason, probably business related ,and its more of a lateral business move as opposed to moving due to a vastly improved software platform presenting itself. By AB's statement above it doesn't appear to eliminate having to true so in the end, after the user has trued their data to their gun, it sounds like it provides the same results that a user would obtain with trued data from Horus software. I admit, I may be wrong in my assumptions but until I see more than marketing hype I won't believe the King has new clothing.
 
It shouldn't be too hard for one to take the same shots at ELR using both the Horus and AB, list the results and boom... Scientific research. IMO, that should be satisfactory to soothe the minds of the curious.
 
How is that misleading? The AB doesn't have two different models unlike the Horus. So if your mil you get the same model that is sold to a civilian. If you want you could get subdued pieces on Kestrel for more of a "tactical look".

No Kestrel is still 100% behind Horus. This statement "isn't from Kestrel" but from the AB team. Horus model is actually getting some excellent upgrades.

The AB and Horus are two completely different solvers. They execute their truing calibrations differently. Two things the DSF do differently is;
1) We do a piecewise scaling and do not apply the DSF to the entire flight, just the small piece of the bullet flight
2) We reference against Mach and not range. This ensures that no matter the DA, the scaling still applies.

If you want greater clearification then shoot Bryan Litz an email and I'm sure he'll fill in the missing pieces.
 
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Having used the AB Kestrel in Oregon I was really happy with the results and the ease of use. I think personally speaking, the fact Bryan includes the Custom Curve feature which is a completely different model than your standard G1 vs G7 debate, interests me. If you read these boards and see the number of people struggling to understand the differences between G1 & G7 as well as the large amount of people who accidentally use G1 numbers with a G7 model, this new Custom Curves solves a lot of those problems. Next we need a well written explanation on how to get the most out of the Custom Curve feature so we start moving down that road as opposed to rehashing the G1 vs G7 argument. How you apply it beyond the samples in the Kestrels.

I will also say, at the monthly class I teach here for a local range, we hand everyone out a Nomad Recon w/ Horus ATRAG installed. I have used the Horus ATRAG Software since the beginning and feel it is a good piece of kit, especially for a new shooters. The fact you can see the, Gun, Atmosphere, & Target on the same page helps. Now this is not the Kestrel version, but under the hood I think the Horus is a bit behind the curve. Especially if you compare it to the AB Software with the custom curve feature.

After about 10 days of use, my feeling is, if you are a casual shooter, once, twice a month kinda guy, and you already own the Horus stick with it. If you are a Finnegan who likes to tweak and explore to the point of almost have to reset the whole damn thing cause you changed everything, the AB unit is a better fit. Again, cause Bryan is probably reading this, put out a detailed paper on using your custom curve. Let guys run with that and you'll attract many more to the AB side of the table. It's different enough to matter. Let them explore, true, adjust and manipulate your numbers to get as much real world data as possible. Then people can start trading curve models.... I know, you don't like my opinions on things at times but trust me this direction has high merit.

As far as the marketing hype, LOL, hey what's a company to do. @Papa Zero Three, careful pointing stuff out, that is how i get into trouble. :)

I haven't shot the AB Kestrel out to distance yet, really only 1100 yards with a 308, so I can't comment on the ELR side of things. Here at 5000ft 1100 yards is not ELR ranges, even with a 308. But i have access to further so I will certainly give it a try. But it was dead on at 800 yards when I did my Cold Bore in Oregon, it went from 6.5 Mils in CO to 7.2 mils on the coast and was accurate enough for me, and with a 308 that is damn good, I was more than centered on the target considering.
 
I did not have to use the DSF on mine for my last load. Really I thought it was for transonic ranges only.

I took one number, which was my 1100 yard data, plugged it in, and it was good on all distances out to 1194 yards!
 
How is that misleading? The AB doesn't have two different models unlike the Horus. So if your mil you get the same model that is sold to a civilian. If you want you could get subdued pieces on Kestrel for more of a "tactical look".

How? From the statement above that you posted from the AB team, and I quote:

"When engaging steel or on a range, this may not matter, but in a military scenario, this could be very different. Since there is no distinction on the AB units for the military and the civilian versions, the AB device has all of the capability that the military is using as well."

Why not just come out and say in plain English, there is no mil version AB? As far as I know, in any official procurement/program of record /contractual way, is the US gov't buying,issuing and using AB other than perhaps a force modernization office rep having a few on hand for test & evaluation.



The AB and Horus are two completely different solvers. They execute their truing calibrations differently. Two things the DSF do differently is;
1) We do a piecewise scaling and do not apply the DSF to the entire flight, just the small piece of the bullet flight
2) We reference against Mach and not range. This ensures that no matter the DA, the scaling still applies.

If you want greater clearification then shoot Bryan Litz an email and I'm sure he'll fill in the missing pieces.

I am familiar with how it is done as far as bryan explains it is done in his book(s). I don't dispute his findings and or refined solution(s), on the contray, I laude him for doing it as it raises the bar for everyone. What I do have issue with is the marketing hype that is being used to make it sound like AB can somehow defy the laws of physics due to bryan's secret sauce curve and inventing a new catchy word for truing.


LowLight said:
As far as the marketing hype, LOL, hey what's a company to do. @Papa Zero Three, careful pointing stuff out, that is how i get into trouble.

HAHA, well heaven forbid I don't want steal your thunder :) But hey, they are legitimate questions that deserve an answer and besides, what are they gonna do, bend my dog tags, send me to Afghanistan? haha :D
 
I am familiar with how it is done as far as bryan explains it is done in his book(s). I don't dispute his findings and or refined solution(s), on the contray, I laude him for doing it as it raises the bar for everyone. What I do have issue with is the marketing hype that is being used to make it sound like AB can somehow defy the laws of physics due to bryan's secret sauce curve and inventing a new catchy word for truing.




HAHA, well heaven forbid I don't want steal your thunder :) But hey, they are legitimate questions that deserve an answer and besides, what are they gonna do, bend my dog tags, send me to Afghanistan? haha :D

If you have dog tags you're just not high speed enough to know what a Kestrel is. How do I know? Cause the clerk in the S3 shop with a shaving profile told me high speed guys tattoo their dog tags on their ribcage. Just sayin man...
 
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Slightly off-topic. :)

Lowlight said:
As far as the marketing hype, LOL, hey what's a company to do. @Papa Zero Three, careful pointing stuff out, that is how i get into trouble.
HAHA, well heaven forbid I don't want steal your thunder :) But hey, they are legitimate questions that deserve an answer and besides, what are they gonna do, bend my dog tags, send me to Afghanistan? haha :D
Lowlight, what trouble? We like you here, and not only because you've created this wonderful site! ;)

P03, do you realize how uncomfortable can bent tags feel while en-route to Syria (especially from A-stan)? :D Just sayin'... :)
 
Listen I don't work for AB, I consult for Kestrel and I do the soldier thing full time. I don't write marketing statements but I will gladly pass along your gripes to the right people. I'll ask for a true clarification on the implementation of his custom drag curves and how they assist the shooter. I can try to explain it to you but I think it would be better for the AB team to do that.
 
I am definitely interested in how the blended Litz curves perform through transonic flight. What is most encouraging with this is the prospect for continued support and improvement, a major boon for me when I think about investing in this as a 'platform' rather than just a single, frozen tool.

That said, I have more than my work cut out for me working with just the FDAC and JBM tables...
 
Well with all this talking about both, I gotta chime in. I have had both units. I Liked my horus it worked, but its geared in my opinion towards military. The applied ballistics is more for hunting and target shooting. I think they both are amazing units, both durable as hell, and kestrel stands behind them all the way. So at the end of the day they both work and they both have amazing warrantys. Just shoot with what you got and quite worrying about the small stuff.
 
Well with all this talking about both, I gotta chime in. I have had both units. I Liked my horus it worked, but its geared in my opinion towards military. The applied ballistics is more for hunting and target shooting. I think they both are amazing units, both durable as hell, and kestrel stands behind them all the way. So at the end of the day they both work and they both have amazing warrantys. Just shoot with what you got and quite worrying about the small stuff.

But I am sure Sniper24INF Posted somewhere here that the Civvy Version of the Horus is Missing something that the Mil Version has??? Why I dont know AND that The AP Model close's that Gap, So which one will tighten the Truing Accuracy issues and how much Out is the worst version in the first place and do these issues only effect Military Bullets???

John
 
But I am sure Sniper24INF Posted somewhere here that the Civvy Version of the Horus is Missing something that the Mil Version has??? Why I dont know AND that The AP Model close's that Gap, So which one will tighten the Truing Accuracy issues and how much Out is the worst version in the first place and do these issues only effect Military Bullets???

John

No, what the civy version of atrag lacks that the military version has is the Loophole function. It is a feature that has nothing to do with truing the firing solutions and really has no civilian use other than for what would be called novelty shooting;it is a feature most would never use or have a need to use even if they did have access to it.
 
No, what the civy version of atrag lacks that the military version has is the Loophole function. It is a feature that has nothing to do with truing the firing solutions and really has no civilian use other than for what would be called novelty shooting;it is a feature most would never use or have a need to use even if they did have access to it.

OK, So this Version can correctly give us the right data where our APPs dont seem to match the True flight of a Bullet when it gets beyoned a certain Range, Yes???

So at what Point/Distance do Our Apps Loose the Actual Bullet Flight because my Apps can be set at any distance and now Everyone is saying that they are not Correct due to Mr Litz's Findings.

Thanks, John
 
When bullets enter the transonic stage their calculations obviously change from sonic speed. Supposedly Litz's calculations are going to get you closer to your target. I would guess that he spent a lot of time working with rounds in the transonic stage and based a calculation from his findings. Unless you are trying to shoot 1200yds with a 308, I wouldn't worry about it. If you are trying to shoot 1200 with a 308 you should consider a hotter round such as a 300 or .338.
 
When bullets enter the transonic stage their calculations obviously change from sonic speed. Supposedly Litz's calculations are going to get you closer to your target. I would guess that he spent a lot of time working with rounds in the transonic stage and based a calculation from his findings. Unless you are trying to shoot 1200yds with a 308, I wouldn't worry about it. If you are trying to shoot 1200 with a 308 you should consider a hotter round such as a 300 or .338.

I understand what your saying so they only way around this it do actual range time and measure every shot,and make tables and run the maths and account for the weather because these Apps loose something within the Program.

John
 
Just for the sake of clarification.

A "custom" drag curve is what Mr. Litz did in his books when measuring the BCs of the published bullets.

Any solver out there works against a drag curve, moreover, you cannot determine a BC unless you first determine the corresponding drag curve.

After all, what is a G1 or G7 BC? It's just the "custom" drag curve of a particular bullet, simply referenced (compared) to a "standard projectile" be it the G1 or G7 ones.

So, the use of a "custom" curve does not eliminate the use of a G1, G7 or G "X" reference. Not at all. The only positive side of this usage is a best fit for the Mach range.

It's ballistics 101...so nothing new here, except for the fact that the curves are just preloaded for a group of certain bullets.

And what PZ3 said about hype is 100% right on the money. Nothing wrong with marketing speech, but I don't see the need to confuse people beyond a reasonable measure.

My point is, AB (Kestrel or not) is a Point Mass solver, and the so called "custom" curves are nothing new at all. And the "DSF" thing is just another fancy word for "truing" or a way to compensate for wrong predictions.
 
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Just for the sake of clarification.

A "custom" drag curve is what Mr. Litz did in his books when measuring the BCs of the published bullets.

Any solver out there works against a drag curve, moreover, you cannot determine a BC unless you first determine the corresponding drag curve.

After all, what is a G1 or G7 BC? It's just the "custom" drag curve of a particular bullet, simply referenced (compared) to a "standard projectile" be it the G1 or G7 ones.

So, the use of a "custom" curve does not eliminate the use of a G1, G7 or G "X" reference. Not at all. The only positive side of this usage is a best fit for the Mach range.

It's ballistics 101...so nothing new here, except for the fact that the curves are just preloaded for a group of certain bullets.

And what PZ3 said about hype is 100% right on the money. Nothing wrong with marketing speech, but I don't see the need to confuse people beyond a reasonable measure.

My point is, AB (Kestrel or not) is a Point Mass solver, and the so called "custom" curves are nothing new at all. And the "DSF" thing is just another fancy word for "truing" or a way to compensate for wrong predictions.

While I do agree with this...the major differences between the Ab and the Horus is that one you can put your curve into if need be, the other you cannot. Due to that feature, the ab will hold an edge over the Horus on longer engagements.

Does that mean you should run out and swap your Horus? No...it will work fine. However if you're frequently shooting 1300 and beyond you would more likely be better off with the ab.

I recently got my ab plugged in all of the data including my curve - dope is near perfect.

That's not something I could do on the Horus.
 
Just for the sake of clarification.......

Any solver out there works against a drag curve, moreover, you cannot determine a BC unless you first determine the corresponding drag curve.
Yes. But:

After all, what is a G1 or G7 BC? It's just the "custom" drag curve of a particular bullet, simply referenced (compared) to a "standard projectile" be it the G1 or G7 ones.
Yes - and by implication Gx coefficient of a bullet shows how much a given projectile differs aerodynamically from the reference ("standard") projectile.

Basically there are two ways to determine trajectory of a specific projectile:
  • Measure it, get empirical data, whatever - and build the entire curve from scratch, specifically for it. One can do that, for example, with Lapua radar data for their bullets. At least some ballistic applications make use of that data in their computations.
  • Create such a curve for each of the 8 "standard" projectiles. Determine what standard projectile your bullet is the closest to, determine your bullet's BC, and with that compute how this specific trajectory will differ from the standard one. This is why ballisticians like Mr. Litz insist that G7 should be used, because modern long-range bullets are much closer to G7 standard projectile than to G1.

But Lowlight performed several tests that demonstrated that a good ballistic solver works OK with either G1 or G7, some were even better with G1. How come? The answer is that neither coefficient (G1 or G7) adequately represents the bullet. More accurate (and more sophisticated) solvers take a lot more into account than just BC. They also adjust BC based on bullet speed (as it decays, dynamically) and other factors. That's what allows them to perform seemingly (from the math point of view) impossible - compute a reasonably accurate trajectory from clearly insufficient and often semi-correct BC data. I say "semi-correct" because the theory behind using BC to represent a bullet as a difference from the standard projectile is based on the fact that the bullet is fairly close to that projectile. Using G7 on a wadcutter is not supposed to work (i.e., is not supposed to give you meaningful and realistic trajectory predictions), and using G1 on Berger VLD shouldn't work either - because the difference between the standard/reference and the "referring" projectiles is just too great.

Several good apps allow entering "stepped" or "band" BC: authors realized that one BC does not represent the entire trajectory well enough, so they allow specifying different BC for different speed bands. As Mr. Litz showed, G7 varies from one velocity band to another much-much less than G1 does. Still, it varies.

So, the use of a "custom" curve does not eliminate the use of a G1, G7 or G "X" reference. Not at all. The only positive side of this usage is a best fit for the Mach range.
Well, as I said, there are multiple ways to define/compute that "custom" curve. One is basing it on the standard curve with "BC offset".
 
Just for the sake of clarification.

A "custom" drag curve is what Mr. Litz did in his books when measuring the BCs of the published bullets.

Any solver out there works against a drag curve, moreover, you cannot determine a BC unless you first determine the corresponding drag curve.

After all, what is a G1 or G7 BC? It's just the "custom" drag curve of a particular bullet, simply referenced (compared) to a "standard projectile" be it the G1 or G7 ones.

So, the use of a "custom" curve does not eliminate the use of a G1, G7 or G "X" reference. Not at all. The only positive side of this usage is a best fit for the Mach range.

It's ballistics 101...so nothing new here, except for the fact that the curves are just preloaded for a group of certain bullets.

And what PZ3 said about hype is 100% right on the money. Nothing wrong with marketing speech, but I don't see the need to confuse people beyond a reasonable measure.

My point is, AB (Kestrel or not) is a Point Mass solver, and the so called "custom" curves are nothing new at all. And the "DSF" thing is just another fancy word for "truing" or a way to compensate for wrong predictions.


When G1 or G7 BC's are selected or entered, the Applied Ballistics solver references the corresponding drag curve (G1 or G7).

However, when custom curves are used, no *standard* is referenced. The drag of that specific bullet is modeled without referencing any standard. Basically, that bullet is it's own standard when you're using custom drag curves.

In contrast to the published data in my book and multiple BC's you can find in other places like Sierra's literature which show 3 to 5 bands, custom drag curves are tables which include over 20 points describing the drag of that particular bullet over it's entire Mach spectrum.

Having said that, you'll notice that most of the custom drag curves are strikingly similar to the G7 standard thru the supersonic range. It's not until you slow below ~Mach 1.5-1.2 where the custom drag of a bullet might begin to diverge significantly from the G7 curve. In other words, the advantage in accuracy for custom drag modeling is typically not apparent unless you're shooting at extended ranges where your bullet slows below about 1350 fps.

At that point, the custom drag of a bullet might be close to the G7 curve, the G1 curve, in between, or something else. That's what the custom curves are about; taking (more of) the guesswork out of trajectory prediction thru modeling actual bullet drag rather than referencing a standard with known (more or less) error.

The reality check is if you're only shooting out to 600 yards with a supersonic round, you're not going to see any more accuracy from a custom curve based solution vs. G7 based or even G1. It's just not far enough to matter (Sorry, I failed marketing)

As for the ballistic calibration; both MV and DSF; that's there to help you dial in if you; a) don't know your exact MV, and b) A custom drag curve is not available for your bullet. If you know your MV accurately and have access to a good custom curve, then the calibration (truing) features are not necessary. They're provided because in reality we don't always have perfect information and a fix is better than no fix.

-Bryan
 
When G1 or G7 BC's are selected or entered, the Applied Ballistics solver references the corresponding drag curve (G1 or G7).

However, when custom curves are used, no *standard* is referenced. The drag of that specific bullet is modeled without referencing any standard. Basically, that bullet is it's own standard when you're using custom drag curves.

In contrast to the published data in my book and multiple BC's you can find in other places like Sierra's literature which show 3 to 5 bands, custom drag curves are tables which include over 20 points describing the drag of that particular bullet over it's entire Mach spectrum.

Having said that, you'll notice that most of the custom drag curves are strikingly similar to the G7 standard thru the supersonic range. It's not until you slow below ~Mach 1.5-1.2 where the custom drag of a bullet might begin to diverge significantly from the G7 curve. In other words, the advantage in accuracy for custom drag modeling is typically not apparent unless you're shooting at extended ranges where your bullet slows below about 1350 fps.

At that point, the custom drag of a bullet might be close to the G7 curve, the G1 curve, in between, or something else. That's what the custom curves are about; taking (more of) the guesswork out of trajectory prediction thru modeling actual bullet drag rather than referencing a standard with known (more or less) error.

The reality check is if you're only shooting out to 600 yards with a supersonic round, you're not going to see any more accuracy from a custom curve based solution vs. G7 based or even G1. It's just not far enough to matter (Sorry, I failed marketing)

As for the ballistic calibration; both MV and DSF; that's there to help you dial in if you; a) don't know your exact MV, and b) A custom drag curve is not available for your bullet. If you know your MV accurately and have access to a good custom curve, then the calibration (truing) features are not necessary. They're provided because in reality we don't always have perfect information and a fix is better than no fix.

-Bryan

Like I said before, I agree on the best fit of a so called "custom" curve does in relation to the Mach number, especially in the transonic region giving its high rate of change.

It's of course a "less compromised" number than an average BC. Again, in that regards it's a better approach, however I'd like to see, if possible, how this usage produces significantly better predictions than when relying on a well established BC (like the ones you measured so carefully). Any ELR data confirming this is welcomed.

Take for example the "custom" drag curves that have been around for several years now, coming from Lapua most of them (and derived from Doppler radar data) and offered for free and available in both JBM and QTU (free version) programs, both examples of well known Point Mass solvers.

Do they made any significant difference in ELR scenarios? Acccording to the experience of many the gain, against a well behaved BC, was not quite significant at all. Indeed in most cases the difference was not even there.

If I understand right your curves were calculated from downrange ToF values, a clever way to obtain them, but if I'm not wrong they cannot compete against the longer observed range yielded by Doppler as well as its sampling rate and size.

Please I'm not saying the use of drag curves is a bad idea or else, far from my intent, just trying to separate marketing speech from reality. On the contrary, the use of darg curves is always a good sanity check against badly behaved BCs.

In that same way, I have to say that the DSF and MV "truing" methods are just another way to somehow compensate for badly determined inputs, but like you wrote in your book, both are limited to an specific range and observed env factors. Other than that, there is the chance of introducing more error than removing them. Please correct me if I misunderstood what's in the book.

All in all, IMHO I think AB given its feature set is a much better option than Horus and clearly a more robust solver.
 
okay, so a novice like me will be just fine with either program, I haven't noticed any price difference in the kestrels with different programs so... is my decision just which color to get or do you guys recommend one over the other for an old grunt with a 700 aac-sd?



P.S. The clerk with the shave chit told me you gotta put one of yer tags in yer boot.
 
okay, so a novice like me will be just fine with either program, I haven't noticed any price difference in the kestrels with different programs so...

Listen to Bryan - he's got research time in the field - I've had conversations with him and he's a also a skilled mathematician. The other guy's just flapping his gums.
 
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I've had the 4500NV AB BT for about a month. It's an amazingly powerful tool. Two stand outs for me: 1) the accuracy of the solutions; and 2) the ability to function without a cell signal. Two relatively minor complaints: 1) the installation process could be more intuitive; and 2) occasional problems with communication between my laptop and the Kestrel via Bluetooth.

My previous methods were a standard 4500 with DA and pre-printed range cards, Shooter on my Droid, and AB on my Droid. The 4500 NV AB BT is a significant step forward. From the Big Empty, ELN.