Re: Any info on Knights Armament's ballistic cal
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Here2Learn</div><div class="ubbcode-body">I use both and they seem to give the same info. If your happy with FTE I would just stay with it. I don't think anything would be gained from switching. </div></div>
My experience differs from yours. I concur with your conclusion though - if one is happy with FTE there's no reason to switch. I got Bullet Flight because I didn't like FTE interface (now I'm better used to it, but still think BF does the UI better).
I got both of them (see threads
here and
here). My current opinion (biased by limited experience) is: Bullet Flight is easier to work with - <span style="text-decoration: line-through">but Ballistic FTE is more accurate</span>.
<span style="font-style: italic">Latest math experiments conducted with the help of Lindy and Robert Silvers (from Knight Armament Co) demonstrated that Bullet Flight does indeed provide accurate results well within the ballpark of JBM and Ballistic FTE. It looks like something wasn't imported right from the Projectile Database to the original profile, but alas no way to examine it.</span>
For example, try them both on the following task (as I did):
<ul style="list-style-type: disc">[*] 0.338 Sierra 250gr MatchKing bullet. (<span style="font-style: italic">Try to use G7 BC = 0.314, or - if your program allows - banded G7 BC from Bryan Litz book.</span>)[*] Muzzle velocity <span style="text-decoration: underline">at zeroing time</span> 2900 fps (weather was 86F, 29.94 inHg (sea level), 78% RH; altitude 100m), rifling twist 1:10 right-hand.[*] Rifle zeroed at 100m.[*] Target distance is 2000m (if it's too unrealistic for you - try 1500m instead).[*] Current weather is: 19F, 29.93 inHg (sea level), 47% RH.[*] Altitude is 68m.[/list]
<span style="text-decoration: line-through">and see which of the programs makes more sense out of it (hint: the results will differ by quite a lot - like 14 <span style="text-decoration: underline">mils</span> or 93 feet). Then decide which program you're going to trust for your first on-target (or near-the-target
) shot at a really long distance.
</span>
<span style="font-style: italic">Now they both do make sense, diverging by 0.1-0.3mRad throughout the range.</span>
<span style="font-style: italic">Also, if you don't mind some programming & debugging - get GEBC (freeware) and see what numbers it gives (in my case it was in between Bullet Flight and FTE).</span>
<span style="text-decoration: line-through">
Repeating:
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I use both and they seem to give the same info.</div></div>
Could you please provide a few (or a couple of) samples - the inputs you gave these programs, and the output they provided? And would you like to expand your experiments by e.g. increasing distance to target (and tell us whether the two programs still stay together regarding predicted drop)?</span>
I must add that Robert Silvers (who supports Bullet Flight) is <span style="font-weight: bold">very responsive</span> - I'm currently in email conversation with him, discussing the potential causes for the differences I'm observing: calculation error? BC difference - as all the programs I used in comparison use different ways to input BC)? pilot error (quite feasible, considering my very limited experience with it)?
<span style="font-style: italic">Update 1. Looks like we narrowed the problem down to the Projectile Database. When I <span style="text-decoration: underline">manually</span> entered banded G7 BC - Bullet Flight output matched JBM to within 0.1-0.6mRad (0.3mRad at 2000m). Entering single G7 BC still keeps the output within the ballpark (0.3-0.4-0.6mRad). We're still investigating. If there are more updates - they'll be here. </span>
<span style="font-style: italic">
Update 2. <span style="font-weight: bold">WTF!</span> Upon Robert's request I was making screenshots from the iPod for him to evaluate. Miraculously everything started working right. All the BC's - those taken from Projectile Database and those manually entered - started giving good output, well within the ballpark of JBM!
So why it was giving me 25mRad drop instead of 39.8mRad will remain a mystery, as - thankfully - I cannot re-create the problem any more, but can re-create the correct result.
Now I'm enjoying both program giving reasonably accurate data, one somewhat more deep - another one easier to deal with.
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