I primarily shoot Hornady 88 eldms, Berger 85.5’s and Berger 130 hybrids and have recently noticed that the Kestrel default values for G7 BC differ from the mfg stated BC. I only started questioning this as I have recently switched to the 85.5's and am having some elevation issues at ranges beyond 700 yards. ES on loads is around 15 FPS, at 2950 FPS. Is this just an error on Kestrel's/AB's end or am I missing something?
Kestrel BC Values are incorrect
- Thread starter Superjet
- Start date
Well yeah, but isn’t he still Berger’s lead ballistics guy? So, would we not have a reasonable expectation that AB G7 will match Berger’s G7 for the 130 HTs?
. That would be a safe assumption but u know what happens when you assume.
There is the banded BC info Hornady provides. If Kestrel/AB track into trans/subsonic their average BC is going to be further down the curve.
The BC value is tied to velocity, not just the shape of the bullet. Most vendors give a single number average that usually works "good enough" at common distances.
Hornady gives 3 different G1 and G7 values at different speeds as shown in the picture for many of their target bullets. As you can see the BC value decreases as the speed decreases.
Their whole chart is here:
Ballistic Coefficient - Hornady Manufacturing, Inc
A-Tip®, ELD® Match, and ELD-X® Ballistic Coefficient Values Hornady originally published “800 yard”* average Ballistic Coefficient (BC) values for ELD-X and ELD Match bullets. This was done to provide the most usable BC from a trajectory prediction st...
The Hornaday 4DOF 5700 uses bullet data developed by Hornady, all other 5700 ballistic meters use bullet data developed by AB. When you use the App to create a profile the phone/pad goes to their database for the bullet information. There is very little bullet data in the Kestrel itself, just a few profiles. Always build your profile in the Kestrel Link Ballistic App and transfer to the Kestrel for optimal bullet data. The best data would be the 4DOF for Hornaday or the AB Custom for AB. These are tested results and allow the ballistic engine to optimize results.
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