@chainsaw, it is a pandora's box
a lot of this is just marketing hype, trying to justify publishing higher BC values than a competitor, or defending low values against inflated ones.
In my experience Berger has a fairly good take on BC values. Litz has done a ton of work, and is not afraid to publish and put data in the public domain.
Here is an interesting article on their website: https://bergerbullets.com/nobsbc/var...with-velocity/
At the end of the day, whatever is on the box or on the website, is just marketing to me. Use that as a guide, but you need to shoot actual drops at distance to verify and get real-world values that work for you.
I have used the Litz G7 values published in his book for projectiles of various manufacturers, and found them to be extremely accurate out to silly distances. If you want the Nth degree of info, have a look at the custom drag curves for Applied Ballistics. @andyanimal31 on here is a huge fan those and has had good results with them
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