Ballistic Apps - 3DOF, 4DOF, 6DOF

[Long Range 338]

I've got a few apps and am familiar with a few more. Does anybody know which ballistic engines are 3DOF, 4DOF, and 6DOF? I know that Lapua's app says its 6DOF, Hornady's app is 4DOF... But what about the others? I know I've read some threads where LL went into depth on why he wasn't a fan of 3DOF and there was a lot of back and forth specifically with the AB guys and now I can't find the old thread - maybe it was on Scout.... Anyways I'm looking for some behind the scenes info for some of the more popular apps, for example:

-AB
-Trasol
-Shooter
-Ballistic AE
-BallisticsARC
-BulletFlight

and others you guys are familiar with. I'm not really asking about FFS or CB as I'm aware they are for different platforms and purposes.

 

[Lowlight]

6DOF is not available in an App, it needs more computing power, however, Lapua is using 6DOF data and it's coupled with Doppler Data. Hornady has this same data too, as do others.


Most Apps are 3DOF, they use the same freeware you can run in Excel, they are not really calculating the extra stuff like SD and CE as they don't have that ability, it's an add-on flat rate number, because a percentage of time of flight based off some old data.




Bison has a pretty simple explanation
http://bisonballistics.com/articles/the-details-of-a-ballistics-calculator-solver

4DOF adds a bit more information, it includes Pitch and Yaw and was written after 3DOF / Point Mass was put out. In fact, the Army white paper on it was written in 1966. Most people, and if you google say, Bryan Litz invented PM, which is completely untrue. He just uses it, that has been around a very, very long time. Just like G7 was first shot and modeled in 1940 but was not used until recently. You can draw a very straight line from McCoy to Litz, others like Hazelton, Ruiz, Boatright, have felt the need to correct his shortcomings. By famously saying "it's good enough for the government" has exceeded its usefulness in my opinion.





Most just copy what McCoy wrote and he felt 3DOF was easy and accurate "enough". But, we are now shooting farther than ever and it's not really accurate enough so you start to see hacks in the formulas to add in the missing details. This is also why we true software. Because none of the original curves line up 100% so you have to bend them or adjust them based on the software method. The Pesja stuff uses their own method vs just changing the MV or BC. Hornady is removing the weak link, the BC and uses the Form Factor which raises or lowers the entire curve vs just the ends.






The difference two is, Point Mass tells us where an object will be at any given moment, "At what point the mass will be in space' with software like ColdBore it knows where the bullet was before and where it is after. 3DOF does not know this, only where it should be at any given moment in space, as noted above.

 

[LastShot300]

Thanks for sharing the info, I found it very informative and interesting, always learning more stuff like this help to hone my LR skills..

 

[Long Range 338]

Thanks for the awesome info LowLight. You sent me on a tangent reading all the info from Hornady and Bison Ballistics. I was probably lost in study for a good 6 hours, hopefully I'm somewhat smarter for all the studying.

So if I understand correctly Lapua is not a real 6DOF app, they are using data they have for their own bullets only they derived from a 6DOF program and are importing it into a 3DOF ballistics engine? Or some kind of 4DOF possibly? While it is a slick little app, I personally haven't shot any Lapua bullets so its just another app without their additional data - or so it appears to my small mind. Not complaining as the app is free so its just a bonus to have it. I was hoping it had some secret sauce somewhere.

 

[damoncali]

Lapua is a legitimate 6DOF calculator, but that's kind of wasted on a phone. They have not to my knowledge explained where they get the volumes of data required for it (they either calculate the data, or the measure it - each has it's drawbacks). So you just sort of have to trust them that it's accurate - some of it is very hard to test (like its dynamic stability calculations). Generally 6DOF calculators are used by engineers to design systems or to explore complex rotational effects like stability, aerodynamic jump, spin drift, large yaws, and swerve. It's overkill for predicting trajectories, and I wish Lapua had released it as a desktop app so we could get the most out of it.

4DOF is a bit of a misnomer - it's sloppy shorthand for "Modified Point Mass", which us more like a 3DOF+ than 4DOF. But that's the shorthand and what Hornady calls their MPM calculator. You need additional ballistic data on the bullets (hornady calculates theirs), but in return you get a very good, mathematically rigorous estimate of things like spin drift.

3DOF has been the method of choice for simple trajectory calculation, and with good, doppler derived drag data, it's very accurate out to what most people would call very long range - well past 1000 yards.

To make things even more confusing, you have calculators like AB, which are 3DOF, but with additional secondary effects (like spin drift and crosswind aerodynamic jump) added in. This makes the results similar to those of a MPM, but they go about the math in a simpler way that requires less data. That doesn't necessarily make it worse, but it is different, and a little more hand-wavey mathematically speaking. You can think of their math as more empirically driven, as opposed to the theoretically driven 4DOF math. (This was a touchy subject a while back, so know that I'm greatly simplifying here. There are pros and cons to each method).

Then you throw in other methods like Pejsa, which is a 3DOF model in that it doesn't account for spin or yaw, but it solves the trajectory in a different way than a normal Point Mass model. There is nothing wrong with Pejsa, but it's no longer beneficial now that we have modern computers. You could even call it obsolete, but that's kind of harsh, since it works.

I'll skip Cold Bore and it's brethren simply because they don't really say how it works, but it appears you can reproduce its results with a 3DOF solver and some custom drag functions. People seem to like the results. I've not used it.

With any solver, the data is the key - the more complex the solver, the more data you need, and the more opportunity to go wrong there is. The KISS way to go about it is to use good doppler data and a 3DOF solver. That will get you way out there. Beyond that, you'll have to talk to guys who shoot a lot of ELR, but I would argue that software doesn't really matter past a certain point - things like 1 fps variations in muzzle velocity and 0.5 mph variations in wind start to matter a lot more than where your theoretical trajectory says you're going to hit.

 

[LastShot300]

With any solver, the data is the key - the more complex the solver, the more data you need, and the more opportunity to go wrong there is. The KISS way to go about it is to use good doppler data and a 3DOF solver. That will get you way out there. Beyond that, you'll have to talk to guys who shoot a lot of ELR, but I would argue that software doesn't really matter past a certain point - things like 1 fps variations in muzzle velocity and 0.5 mph variations in wind start to matter a lot more than where your theoretical trajectory says you're going to hit.

Good data is vital, which is obvious. But it is not only the data, it's how the underlying algorithm crunches the data. If this statement wouldn't be true, all solvers of any kind will be equal but they are not.

And then this discussion becomes moot, though it's not, simply because when feeding exactly the same data some solvers are more accurate than others as attested by lots of ELR shooters who run the non-3DOF Point Mass solvers.

 

[Lowlight]

Here is the 4DOF or Modified Point Mass paper from 1966 ... Link

It's a bit odd the guys that advocate 3DOF shoot down 4DOF or changes it incorporates ... the key to their argument, 3DOF is good enough and simple. But when you talk to guys doing 4DOF or more they can cite several shortcomings in the software.

That was the argument initially and even recently against both Hornady and ColdBore, that they are complex and not just giving a nod to the errors like 3DOF does. They like it better that they can add a simple flat rate value vs actually putting in real data for the actual bullet being shot. Your solutions are not for your actual bullet. Yes, it requires more effort and you can't just copy and paste the formulas into your App using the Freeware like they do. When guys actually fix the errors they get shot down as being unnecessary. I find that funny.

We point out the real world issues and errors and guys will argue how 3DOF is great and good enough, but we can "See" the problems they refuse to address.

Pejsa is smarter even today as he is non-G Dependent. He does not weight G7 vs G1, both give you the same results. Hornady sees this by using the Form Factor to address this problem. Competitors will say, BCs are marketing, BCs are Flawed, and yet they weight these values because they are using the original data from 100 years ago. If you understand all the models are flawed, you can actually fix them. But if you call the models good and take the shortcut of using what they always have, we have what we see today. Bullshit.

Go back and actually read Pesja and clearly, he says what others know but refuse to fix. Hornady fixed it using the form factor, Coldbore fixes it by including more calculations. FFS fixes it by not being G dependent. `

I just don't see these guys advocating for 3DOF as being honest but more about defending their lack of effort.

 

[damoncali]

To me, the goal isn't "which solver is more accurate with the the same data", but "which solver provides acceptable results with the easiest to acquire data". Assuming good data, 3DOF < MPM < 6DOF. No arguments there. However, getting data for even 4DOF is non-trivial, and bad data can be worse than other methods. This was essentially AB's argument when the 4DOF calculator was released - that the PRODAS based coefficients used by the Hornady 4DOF solver were not good enough to justify the use of a 4DOF solver. Whatever. I don't really care. They're booth legitimate approaches and well beyond what is needed. Given a choice, I'd pick 4DOF and good data if I cared a lot about spin drift or AJ. But I'd listen to an argument about PRODAS and it's fidelity with regards to the bullet at hand and wouldn't accept it as obviously better than AB's approach without testing. The entire reason MPM was developed was to get some spin related insights without having to go to a full-blown 6DOF. If it wasn't potentially better than a plain 3DOF model, it would never have been published. (Although I appreciate AB's concerns about data, I found their argument to be weak. Hornady's approach is definitely legit, and I get why they were sort of offended).

I would definitely be concerned about the level of fidelity of the data going into Lapua's calculator. I have no reason to think they don't do a good job at Lapua, but it's a lot of work, and again, bad data can be worse than no data. But since almost nobody cares about what 6DOF actually gets you, it doesn't really matter. Assuming their data is good, you're not going to do any better. It's amazing to me that we have access to a free commercial 6DOF calculator that you can run on a phone. We live in a golden age.

I will categorically reject the idea that Pejsa is in any way superior to 3DOF, though. Even Pejsa said that. It's easier to calculate, but only because it ignores some of the physics. Useful in the 80's, but not so much anymore. If you can run a 6DOF on your phone, you surely don't have to worry about the computational savings between Pejsa and Point Mass.

All in all, given that we've basically evolved past G1 and G7 based drag models to bullet-specific drag functions, I think most shooters will be very happy with a simple 3DOF solver, even without AB-style enhancements. 4DOF is icing on the cake. 6DOF is really not needed by the vast majority of sporting shooters, but can provide some useful insights to advanced users. Any solver is going to have limits at ELR when it comes to predicting precise bullet strikes (because our data just isn't that good, even at its best), and you're going to have to develop specific experience with the bullets used at that distance. Software will only get you so far.

So, yeah, 3DOF is popular because it's easy and "good enough". I don't think anyone would honestly dispute that. But regardless of the software, data is the most important thing to worry about. The software is free. Data is hard to come by (although everyone seems to have a doppler radar these days. Again - golden age. We have much to be thankful for on this Christmas eve.)

 

[LastShot300]

To me, the goal isn't "which solver is more accurate with the the same data", but "which solver provides acceptable results with the easiest to acquire data". Assuming good data, 3DOF < MPM < 6DOF.

I'm confused, please bear with me. If you don't care about "same data" how do you compare apples to apples? How do establish a baseline to compare one against the other? Am I missing something new here?

I mean, not talking about the "easiest to acquire data". If any given level of effort was put on the data, to the point we can label it "good, accurate data" then the data itself gets out of the equation by simple arithmetic.

Bottom line, with the SAME QUALITY DATA some solvers are the best to predict ELR engagements than the usual bunch of 3DOF Point Mass programs, and by simple logic, if that alone wasn't true then we have, myself included, a bunch of idiots running the "other" solvers. That cannot be true IMHO.

3DOF (with or withou extensions) is good enough, no argument here, since most people don't see the need to shoot ELR (at and beyond transonic) and the price of most is insanely cheap, which I guess is the main reason for their popularity including a good number of pages offering free programs such as JBM, AB, Bison, Gunwerks, etc.

So, I wouldn't dare to say all is the same, because the real world experience of tons of shooters have proven the contrary. Hard to argue with reality

 

[LastShot300]

That was the argument initially and even recently against both Hornady and ColdBore, that they are complex and not just giving a nod to the errors like 3DOF does. They like it better that they can add a simple flat rate value vs actually putting in real data for the actual bullet being shot. Your solutions are not for your actual bullet. Yes, it requires more effort and you can't just copy and paste the formulas into your App using the Freeware like they do. When guys actually fix the errors they get shot down as being unnecessary. I find that funny.

Pejsa is smarter even today as he is non-G Dependent. He does not weight G7 vs G1, both give you the same results. Hornady sees this by using the Form Factor to address this problem. Competitors will say, BCs are marketing, BCs are Flawed, and yet they weight these values because they are using the original data from 100 years ago. If you understand all the models are flawed, you can actually fix them. But if you call the models good and take the shortcut of using what they always have, we have what we see today. Bullshit.

Crystal and coming from a guy with tons of real world ELR experience hard to match by most. Once again, hard to argue with reality, which has the nasty habit of not listening to what we say.

 

[damoncali]

I'm confused, please bear with me. If you don't care about "same data" how do you compare apples to apples? How do establish a baseline to compare one against the other? Am I missing something new here?

I mean, not talking about the "easiest to acquire data". If any given level of effort was put on the data, to the point we can label it "good, accurate data" then the data itself gets out of the equation by simple arithmetic.

Bottom line, with the SAME QUALITY DATA some solvers are the best to predict ELR engagements than the usual bunch of 3DOF Point Mass programs, and by simple logic, if that alone wasn't true then we have, myself included, a bunch of idiots running the "other" solvers. That cannot be true IMHO.

3DOF (with or withou extensions) is good enough, no argument here, since most people don't see the need to shoot ELR (at and beyond transonic) and the price of most is insanely cheap, which I guess is the main reason for their popularity including a good number of pages offering free programs such as JBM, AB, Bison, Gunwerks, etc.

So, I wouldn't dare to say all is the same, because the real world experience of tons of shooters have proven the contrary. Hard to argue with reality

I don't think we really disagree.

6DOF requires more data (a lot more) than 4DOF. 4DOF requires significantly more data than 3DOF+ (AB style). 3DOF+ requires just a little more data than plain 3DOF. So *if* 3DOF+ is getting you the same results as 4DOF, then 4DOF is a bad choice. That's all I'm saying. And if 3DOF gets the job done, then you're certifiably crazy to go to 6DOF trouble. A MPM or 6DOF solver is not significantly harder to make than a plain 3DOF solver. The reason nobody does is because the data they require isn't easily obtained.

For the vast majority of shooters, 3DOF - just plain old JBM or the equivalent, gets you 99.5% of the way there, which is plenty good enough. It's only a rarified few who care to tweak that last 0.5%, and I would argue that they don't really have to. But I would never say that they shouldn't. Once upon a time, people "got the job done" with drop tables in the back of reloading manuals - back when 600 yards was "long range", and look at the progress we've made since then doing "unnecessary" things - people are starting to complain that a 3" X-ring at 600 yards is too easy. So I'm all for pushing limits. If you like whatever package you like to use, I'm certainly not going to tell you not to use it in favor of something else just because I have some preference for a certain theoretical nuance.

The reality is that we have better solvers than data. It's my view that future improvements the accuracy of ballistics computation will come in the form of better data, not better solvers. Ballistics software is not the largest problem limiting the effective range of small arms. I think wind uncertainty and velocity inconsistency are the two problems to solve right now. Trajectory prediction is low down on the list.

 

[Lowlight]

Here is the clue everyone.

It's only "easier" and "good enough" for the publisher of the apps, what he is talking about, in terms of acquiring data is on the publisher side and not the end user side.

These guys are advocating simpler software for them to write and make money off of. They are not interested in fixing the problems and doing it right. It's about simplicity in design which allows them to take shortcuts. At which point when things don't line as needed they can just spin the tale and blame the end user.

Meanwhile, guys have to true a known MV to the tune of 100fps or more. Forget the fact that technology has progressed, we have better chronographs, better powder, better barrels, better bullets, they want to use 100-year-old drag models. After which when things don't line up they will just force you to bend the curve out of whack.

If Pesja from the 80s is bad, how is it the older information is better? He at least admitted the data being used to determine these predictions were first developed for artillery and then by shooting inside 400 yards. The long-range predictions back in the day were generally inside 700 yards. Instead of embracing advances they want to couple our modern advances in technology with ancient data based on bullets we are not even shooting anymore. Why you ask, read it above, it's easier ...

Bottom line they embrace shortcuts and ease vs putting in the effort to collect real-world data out to the distance we shoot, bullet by bullet and then modify the data to match. Nope, take the original intent G1 number compare that old curve to the same old G7 curve which barely matches by its own right and then claim, good enough. When I test stuff I actually shoot it to transonic and don't model it using sub loads or short-range data on a subsonic bullet. I shoot it to distance and collect the data yard line by yard line. In the end, my data is stronger. But I am not trying to sell an App to the masses.

PS, Hornady collected Spark Range Data and used the latest version of PRODAS, they also had a guy with more experience doing this than most in Dave Emry. Look really close at this slide, this is from the spark range, note the pins on the back of the bullet.

 

[Lowlight]

To add in, here is the data collected by Hornady,

T
What they need to solve for

 

[Lowlight]

Here is another comment on the false equivalency argument,

Once upon a time, people "got the job done" with drop tables in the back of reloading manuals - back when 600 yards was "long range", and look at the progress we've made since then doing "unnecessary" things - people are starting to complain that a 3" X-ring at 600 yards is too easy.

This is exactly the issue, our rifles, our bullets, our equipment is better. Making a 3" X Ring look too easy has absolutely positively NOTHING to do with software. That speaks to the increased accuracy of the shooter and rifle system in general. Hence the software now needs to catch up to modern times and our increased capabilities when shooting.

The software being peddled is not better, it's keeping to the publisher line of good enough. They know 75% of those using it are not reaching peak capabilities, they know the average range in the US is 200 yards. So they play a numbers game, they argue that inside 1000 yards everything is rosy. Well, our equipment is much better inside 1000 yards because we continue to push the envelope beyond this range. But the software cannot keep up. If everything was the same, if the Point Mass numbers were all good, every piece of software would be on, but clearly, that is not the case. Under the hood, it's all supposed to come from the same starting point. 3DOF PM Calculations, but as noted over and over, put the same end user data in, and get wildly different results out. That is easy enough to see without going to a range.

The software is not needed to hit an X ring, it's needed to predict the unknown. It's not needed where you can effectively rezero the rifle to the aiming point, but where you have to adapt on the fly. When you have a KD Range with convertible sighters, do you really need software? You know it's 300, 500, 600, 800, 900, 1000 yards. Everything in the middle or on the ends is irrelevant. Yet it's in those other areas we need software to fine tune the values. We can dope a certain amount distance but we cannot dope every distance, thus the need for software.

If the elevation predictions are so easy and good enough, why are the winds and the drifts so far off reality? How about putting the effort into the wind values, into fine-tuning the use of multiple wind zone to help combat the random nature of the effect. If 3DOF is more than good enough for the elevation where is the effort on the drift side of things which is clearly a weak point.

Lazy, that is why, we can copy and paste the formulas, we can detail the interface, but after that, just update the app to run through the IOS changes and your good, let the easy money roll in.

What they failed to understand is, if they required more of the shooter, more of the end user to confirm their data in order for these predictions to be better, they will do it. But we don't see anyone asking anything of the shooter beyond the basics. It's pretty easy to say, "If you do A, the answer will be B, if you do X the answer will be Y, and if you do A and X the answer will be Z, that would solve a lot of the truing issues we see. Like asking them for instructor level details to help the average shooter. I have been told flat out "NO" they want it all in-house, or just gray enough to confuse the average guy. Where is the instructor level videos and powerpoints to disseminate out to those truly interested?

 

[damoncali]

I don't disagree that accuracy has little to do with software. I was merely stating that what was considered a long shot 20 years ago is routine today - not even "long range". Nobody had much use for a ballistic calculator at all when everything was under 300 yards. Better scopes and bullets have got us out to ranges where the software actually becomes useful. But better computers have made a lot of what the old engineers figured out less useful.

I also don't disagree that the constant wind assumption used by most calculators is insufficient to produce good results. But again, I think we have a data problem rather than a model problem. It's trivial to implement a continually varying wind vector (in all three dimensions) into a point mass (or MPM or 6DOF) calculator, but I can barely keep track of a couple wind flags in real time, let alone feed them into a calculator. That's where the sci-fi wind measurement stuff they're developing these days comes in. Once that is nailed and affordable, I guarantee you it will be integrated successfully into a 3DOF program running in a scope, and wind calls will be dead nuts on out to transonic for any bullet with a reasonably accurate BC.

There's probably a lot of nuance left to study when it comes to transonic stability and pushing through it accurately. Most of the military studies just aren't concerned about that level of precision. For example, there's a study of rifling on aerodynamics out there. They concluded it wasn't worth worrying about because it only impacted things by a couple percent. Well, some of those old timers probably thought (correctly for their application) that a couple percent of BC was insignificant. We have higher demands than they do - a 2% bump in BC will sell a lot of bullets and pointing dies. It's not that the science isn't known, its just that nobody has had any reason to apply it in detail for this purpose. Whether or not these types of findings can be usefully boiled down to a Cd and run through a 3DOF, I don't know. Maybe, maybe not. Probably depends on the bullet. There's a really cool paper on tubular bullets on a thread somewhere here. That's a wide open topic that could be really interesting.

Personally, to the extent that we want better software, I like Hornady's approach (and by extension, Lapua's), and I hope they continue to find value in pursuing that level of detail. It will only lead to more discerning customers and for more research to be done. Engineers don't learn this stuff without doing it, so even though I don't think there's a strong need for MPM or 6DOF at the moment, I'm glad that the industry is developing that expertise. The old timers are dying, so it's great to see that info passed on to a new generation.

I can't speak to the business motivations of various companies, but I agree that I would like to see more transparency from all involved. Lapua has been pretty open. I'd like to see more from the others. None of them invented any of this stuff. They may as well share their knowledge with their customers. That's my view at least. Obviously, they disagree, and I'm sure they have their own reasons. It's not like ballistics or bullet design is a black art. There is no secret sauce to hide.

 

[timintx]

Frank that is a great point about truing the wind once the drops are matching and one of the most obvious problems with the programs I see people using.I use Ballistic AE. It has one of the best advanced wind configurations I have seen and can be configured for any terrain situation but I still have to true the wind drifts as you spoke of. I am working to get a drone with a wind meter to check these issues soon up towards the apex of a trajectory in the 2000-3500 yd ranges to see if it is in fact windrift due to drag function or input error of windspeed at 1100 ft off of the ground.But have seen exactly what you speak of.I find myself changing the BC again to match the wind drifts and the drop which seems impossible sometimes

 

[_Windrider_]

How i feel right now after reading all this.

 

[Long Range 338]

So to kick this horse one more time, I have to ask to better inform myself. This may be info that’s not really available about the different apps from the companies but I’ve been searching the websites and not getting much in the way of specifics.

Trasol/CB - uses a mix of data and methods to extrapolate their dope. CB is a 6dof but is TRASOL a 4dof or where does it fall into the mix?
Hornady - calls itself 4dof. Is it still a 3dof just using Doppler data instead of G drag info? If it’s still a PM calculator it sounds very similar to what AB is doing as far as drop data.
AB - How does it differ from Hornady other than trying to sell the CDMs individually as it’s still using the Doppler info to use instead of G drag, correct?

Im only asking about drop here not wind, AJ, CE or other effects. In following the comments in the ELR threads I find myself coming to a realization that at some point I’m going to have to go to a 6dof solution. So it really boils down to how far can I realistically go with the apps before needing to drop a bunch more coin to get good data? I’m kind of hitting the wall at about a mile now and I’m certain I am part of the problem that needs to be solved. Of course I realize lots of practice is as important as the equipment but at the same time I feel just throwing lead down Range until something connects could be a bigger waste of time and money than getting better equipment and better documenting and understanding the ballistics. I’m remote so finding somewhere to practice is not the deciding factor, finding time is much more difficult.

 

[damoncali]

Trasol/CB does not specify clearly how they calculate last I checked. It is not 6DOF, however. The only commercially available 6DOF calculators that I am aware of are PRODAS (which really isn't even a solver the way most people think of one) and the Lapua app. Maybe there are some others I don't know about.

Hornady is Modified Point Mass (MPM), also known as 4DOF, which is just point mass plus some information derived from spin and bullet aerodynamics. It was developed back in the old days to investigate things like spin drift without having to resort to a full blown 6DOF calculation, which was very computationally expensive (slow) and required very difficult to obtain data. Today, it's not appreciably faster than 6DOF, but it is still much less data-hungry than 6DOF. FWIW, I dislike the term "4DOF", because it really isn't. It's engineer jargon/shorthand, but I think it confuses people who don't know exactly what it is. MPM is basically a 3DOF solver, plus some extra.

AB is Point Mass, aka 3DOF, with some additions regarding spin. It is in the same category of calculator as MPM, but I would say it's less mathematically rigorous. It's a different approach to the same problems solved by MPM, but without having to use MPM levels of data, which are non-trivial to collect.

Almost every other calculator is just plain Point Mass, which does not account for spin at all.

None of these methods have anything to do with G-functions or Doppler, which are just different ways of describing a bullet's drag. You can use a G-function or a Doppler table in any of the above methods (if the developer provides the interface to do so). Lapua's old point mass solver could handle doppler data out of the box, for example. I have written a plain point mass solver that does not use BC's at all - just Doppler tables.

Hornady, Lapua, and AB seem to be using radars to feed their calculators these days. That's as good as it's going to get. Warner Tool Company publishes their Doppler data, which is also awesome (although I'm not sure how you'd use Warner's data without writing your own solver, or at least converting it to Lapua's format, which I if I recall is a rebranded version of QuicKTarget).

You do not need a 6DOF solver. 6DOF is for investigating things like large yaw in indirect fire situations, epicyclic swerve, and dynamic stability. Simple trajectory calculations are well handled by good, accurate drag data (such as that provided by Doppler) and any of these 3DOF-ish solvers. There's nothing wrong with using Lapua's app if you are shooting their bullets (and getting good results from the app), but it's overkill. And PRODAS is engineering software (with the associated price tag), not a ballistics app. Whole 'nother ball game.