Ballistic FTE (IPhone) Trajectory Question

[mtn grizzly]

All
I have been working with my Ballistic FTE software and am getting a significant error at long distances. The software gives me fairly good data (+/- .4 MOA ) to 600 yards and then things get off. At 1K I am hitting dead on with 32.5 MOA but the software is telling me 30 MOA. I am shooting the 123 Scenar and my velocity, and all other parameters are dead on.

Can anyone explain to me why the data is wrong for my application?

Thanks in Advance
Mtn Grizzly

 

[KeithR41]

Re: Ballistic FTE (IPhone) Trajectory Question

Could be anything. Wrong B.C, altitude, baro pressure, velocity, etc.


You'll just have to play with it. Mine is within .1 mil at 1K.

41

 

[Nostradumbass]

Re: Ballistic FTE (IPhone) Trajectory Question

I've experienced the same problem with the same bullet.....can't figure it out either. I think it must be me putting the wrong input in the equation. Maybe scope height, or maybe slightly off on my muzzle velocity.

 

[mtn grizzly]

Re: Ballistic FTE (IPhone) Trajectory Question

Roger that! My velocity readings are dead on and have been checked numerous times over two chronographs 2842 fps ES 11 SD 5 The rifle groups about 6" at 1K but I am getting a true error of 2.5 MOA at 1K (Thats Huge)

 

[Rich Emmons]

Re: Ballistic FTE (IPhone) Trajectory Question

Lapua is far from advertised BC try about .455 G1 if i remember right
main error may lay on your pressure thouh.

 

[captrichardson]

Re: Ballistic FTE (IPhone) Trajectory Question

At the longer distances, all of the input variables become very critical for accurate data output.

Environmental - Temp, Dens Alt, Humid, etc.

Rifle - Bore Height

Ammo - Correct BC, Velocity, etc.

Some of those variables can be off a little, and you will not really see the errors produced in the short range data output, which can lead you to believe that your data input is correct.

That old saying, $#!@ IN = $#!@ OUT, is very true for ballistic calculations at longer ranges.

If you are sure your data input is 100%, then you may also want to check other things like if your scope tracking is 100%. Working on some ballistics problems, I actually found out I had a scope that had a tracking error in the last 10 MOA of adjustment.

I am not trying to say the Software can't have a problem, but I have found that when I get my input data correct, I can get output data to +/- .25 MOA out to 1,200 yards.

Best of Luck,
M Richardson

 

[AKAce]

Re: Ballistic FTE (IPhone) Trajectory Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Rich Emmons</div><div class="ubbcode-body">Lapua is far from advertised BC try about .455 G1 if i remember right
main error may lay on your pressure thouh.</div></div>

+1 they use Way over Rated BC's... That was the reason I started with them, but ended up with A-Max. Drop the BC down till it's right.

When trying to make Progs match Dope...
Adjust Velocity to change the closer stuff.
Adjust BC to change the Further stuff.

 

[spot69221]

Re: Ballistic FTE (IPhone) Trajectory Question

The scope could never be wrong, or could it?

Seems lots of bullets have inflated their BC, Lapua seems to be one of the closer ones for me though.

 

[mtn grizzly]

Re: Ballistic FTE (IPhone) Trajectory Question

All

Thank you for the help I will adjust the BC until things match up better

 

[cap2031]

Re: Ballistic FTE (IPhone) Trajectory Question

What about Sierra Match Kings? The Ballistics FTE has the variable BC for the actual Sierra, this is cool as it calculates based on the change in BC as it slows throughout its range. I've found that its dropped the range quite a bit on the .308 and 300 winmag to what I think is more realistic. Getting out to 2000 would require a hefty 40 MOA base with lots of travel in a scope tube plus use of the holds in the reticle. So that seems more realistic, but I've yet to confirm this. This is all versus what seemed to be too easy getting to 2000 so I think the variable BC with the right drag coefficient is the way to go with the iphone FTE.