Range Report Doppler Comparison of Point Mass & LB3

[Lowlight]

Guys as discussed in the other thread regarding G1 versus G7, I was given some comparison data that was done using Doppler.

<span style="text-decoration: underline">About the Test: </span>

This information is from Spain, their doppler facility at <span style="font-style: italic">“La Marañosa”</span> using the 250gr Scenar and the 50BMG

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">It’s a fair comparison by all means. Same input, press enter and let’s compare the output to the Doppler baseline.

No <span style="font-style: italic">“tweaked” or “false manipulation”</span>…<span style="text-decoration: underline">facts are precisely that…facts.</span>

The “0.0” point in the Y-axis indicates the Doppler baseline. The curves are “absolute algebraic differences” from that baseline, in MRAD or Feet/Sec, depending on what ballistics parameter was tested.

All distances are in meters.</div></div>

As discussed you can calibrate and tweak the data to match, but was raw data as presented.

The Point Mass (3DOF) method is used by the following free and commercially available ballistics programs: JBM (web), Berger, Litz, RSI, Ballistics FTE (iPhone), iSnipe (iPhone), BulletFlight (iPhone), Shooter (Android), FieldCraft (ex ABC by CheyTac), Balistika, Quick Target Unlimited, JBallistics, BigGameInfo (web) plus many others. The algorithm is well known and free computer code is available to download from the Internet.

The Pejsa method is used by the following free and commercially available ballistics programs: FFS (Field Firing Solutions), BallistiX, Dr. Pejsa’s own plus some free spreadsheets like BfX. One of the typical issues that are encountered with most of the usual solutions is that they are limited to supersonic velocity values, something very critical to take into consideration when evaluating these programs. The algorithm can be studied in the books published by the author.

LoadBase 3.0 engine is proprietary and is not available outside the packages implementing it.

 

[bigwheeler]

Re: Doppler Comparison of Point Mass & LB3

I wasn't even aware of the LB3, let alone it being that different. Found a quick article on why.

http://ukvarminting.com/forums/index.php?showtopic=11543

Great charts, explains a lot as to why real data never matches computed data.
Thanks.

 

[mouse07410]

Re: Doppler Comparison of Point Mass & LB3

Thank you for providing this info! These results make perfect sense. LB3 does it own hybrid thing, so no wonder it come out as accurate as it does, and for the Point Mass Solvers G7-based calculations are closer to the truth than those based on G1.

 

[Lowlight]

Re: Doppler Comparison of Point Mass & LB3

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mouse07410</div><div class="ubbcode-body">Thank you for providing this info! These results make perfect sense. LB3 does it own hybrid thing, so no wonder it come out as accurate as it does, and for the Point Mass Solvers G7-based calculations are closer to the truth than those based on G1. </div></div>

True,

However you can adjust the G1 of a Point Mass Solver to be equally as accurate. The ability to band the BC is there for a reason and does very well in adjusting the curve model to fit the actual curve.

Remember this is unadjusted data... Adjusted Data is a different story, as I fully believe when you actually shoot it both need to be adjusted to fit the system.

 

[mouse07410]

Re: Doppler Comparison of Point Mass & LB3

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mouse07410</div><div class="ubbcode-body">Thank you for providing this info! These results make perfect sense. LB3 does it own hybrid thing, so no wonder it come out as accurate as it does, and for the Point Mass Solvers G7-based calculations are closer to the truth than those based on G1. </div></div>

True,

However you can adjust the G1 of a Point Mass Solver to be equally as accurate. The ability to band the BC is there for a reason and does very well in adjusting the curve model to fit the actual curve.</div></div>
Precisely. It just looks like it's more of a headache to adjust a G1-based solver because it would need (many?) more reference points along the curve to "whack it in sync" (and that's most likely is what LB3 is doing, among other things). But I totally agree with you.

And this is why I swear by software that allows banded BC, especially when it does not limit how many velocity bands I can define (Bullet Flight and Ballistic FTE allow up to 4 bands, Shooter and Senior Pro have no limit).

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Remember this is unadjusted data... Adjusted Data is a different story, as I fully believe when you actually shoot it both need to be adjusted to fit the system. </div></div>
Yes... But, e.g., Bullet Flight gave me first-shot hits on steel plates up to 900 yards, and that's with me botching the wind calls more likely than not. I used banded G7 BC from Bryan's book, MV measured on the chrono, range verified by LRF, and the actual weather data from Kestrel 4500. <span style="font-style: italic">I even enabled Spin Drift correction in the program!

But not Coriolis - was too lazy to look up the azimuth.

</span>

One question I have is - if I get a chance to shoot 338LM at 1800m+ (and collect the dope, of course), how to use it to calculate and add BC's for transonic and subsonic velocity bands (leaving the higher-velocity "proven" BC's alone). The starting point would be the drag curve that Bryan provided in his book...

 

[Lowlight]

Re: Doppler Comparison of Point Mass & LB3

FFS gave me first round hits out to 1530m with G1... what is your point ?

I would be happy to put $500 up to Wounded Warriors shooting UKD targets to any distance you like with me using G1 and anyone else using G7 ?

I also have used Ballistics with G7 and Bulletflight with Banded G1 and had better success to 1000 yards using a 308... with G1, in the end, Ballistics required me to adjust the G7 down to match.

So the fact, you got lucky and hit with G7 is pretty irrelevant in my opinion, because Banded data for G1 is easy to find, and requires the exact same effort when setting up the system with G7, it doesn't change the facts that either can be equally effective if used correctly.

For too many years the standard was G1 so data is extremely common, like changing a 175gr BC from .505 to .496, that is so common most don't even find the .505 information they go straight to .496.

Splitting hairs and anecdotal data can be found on both sides...

 

[Lowlight]

Re: Doppler Comparison of Point Mass & LB3

Also, one would have to ask, if you blew the wind call and added SD what would have happened if you got the wind right ?

There is a reason the original Ballistic Program has a utility in place of SD called Shooter's Drift where you adjust the calculations by shooting at 600 yards to include the shooter into the equation.

For my shooting out to 2100 yards in Oct, I turned SD on too, but only used half the recommended value, and managed several first round hits... again, pointless because what works for me may not work for you, or the next guy. Until the Human Factor is considered scientific data is flawed as it is no longer relevant due to the shooter's errors which easily eclipse the small changes caused by such things as SD or CE. Especially when put up against wind drift at such distances.. your blown wind statement says it more clearly than anyone could.

 

[mouse07410]

Re: Doppler Comparison of Point Mass & LB3

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">FFS gave me first round hits out to 1530m with G1... what is your point ? </div></div>
My point was going to be that using an accurate (and preferably banded) BC with a decent ballistic computer, could make it unnecessary to adjust that BC to get "close enough" on target. Needless to say I've got nothing to match a first round hit (or any round hit

) to 1500m+. Never shot that far (no place to do that), and not sure I'm ready as a shooter yet - still need lots of training and practice.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">I would be happy to put $500 up to Wounded Warriors shooting UKD targets to any distance you like with me using G1 and anyone else using G7 ? </div></div>
It would take quite a bit more of training before I'd consider accepting a challenge like this.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">I also have used Ballistics with G7 and Bulletflight with Banded G1 and had better success to 1000 yards using a 308... with G1, in the end, Ballistics required me to adjust the G7 down to match. </div></div>
An interesting and useful observation. I'd appreciate if you could share (a) what the bullet in question was, (b) what the original and final G7 BC were, and (c) whether you were satisfied in the end that the adjusted G7 BC gave prediction as accurate (or better?) as the banded G1.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">So the fact, you got lucky and hit with G7 is pretty irrelevant in my opinion, because Banded data for G1 is easy to find, and requires the exact same effort when setting up the system with G7, it doesn't change the facts that either can be equally effective if used correctly. </div></div>
Yes, if used correctly - both can be equally effective, as the LB3 example proves. In fact, for the graphs you posted it looks like LB3 is "optimized" to deal with G1 and does it better than G7. And yes, the user effort to set it up is exactly the same. <span style="font-style: italic">My point is that G1 would require more reference points along the curve to get it right - but good software would hide it from the user (it's the under-the-hood complexity that users don't see).</span>

I'm aware of only one manufacturer - Sierra - that posted banded G1 BC for their bullets. And for some manufacturers -Speer for example - I could not find even a single G1 BC (.264 140gr Grand Slam), let alone banded and/or G7. Of course, Grand Slam is not a long range bullet, so one may legitimately ask "who cares".

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">Also, one would have to ask, if you blew the wind call and added SD what would have happened if you got the wind right ?

There is a reason the original Ballistic Program has a utility in place of SD called Shooter's Drift where you adjust the calculations by shooting at 600 yards to include the shooter into the equation. </div></div>
Good question. Hopefully the answer is "would've hit it dead center"

, but I understand what you mean. Again hopefully, one of the next shooting sessions would provide the answer.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">For my shooting out to 2100 yards in Oct, I turned SD on too, but only used half the recommended value, and managed several first round hits... again, pointless because what works for me may not work for you, or the next guy. Until the Human Factor is considered scientific data is flawed as it is no longer relevant due to the shooter's errors which easily eclipse the small changes caused by such things as SD or CE. Especially when put up against wind drift at such distances.. your blown wind statement says it more clearly than anyone could.</div></div>
There's no question that in my case the shooter's errors eclipse SD and other minor predictable corrections. Now I don't <span style="text-decoration: underline">know</span> that I blew those wind calls (and the wind was mild, between 2mph and 5mph), but I don't know that I got them right either - and lacking sufficient experience I prefer to lean towards more caution.

Yes I understand completely what you're saying about human factor. I'm still working on being consistent enough for that factor to be "computable".

<span style="font-style: italic">I contemplated what Lowlight said about Shooter's Drift and about the fact that even great experience and skills doen't free a shooter from this... I did not fully appreciate it before...</span>