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## Main Question or Discussion Point

I have been attempting to calculate a Ballistic Coefficient (BC) from two velocities of a known distance using the formula:

for example

In this example, I have compared this result with the vendor's published BC (.415) and two online BC calculators (.455 and .422) and I'm considerable off.

As I understand it, air density needs to be factored in.

Can someone help with the correct formula?

BC = (AirDensity * Distance) / ( SQRT(Velocity0) - SQRT(Velocity1))

for example

AirDensity = 0.0751265 lb/ft³

Distance = 100 yards

Velocity0 = 3000 fps

Velocity1 = 2772 fps

BC = 0.0329

Distance = 100 yards

Velocity0 = 3000 fps

Velocity1 = 2772 fps

BC = 0.0329

In this example, I have compared this result with the vendor's published BC (.415) and two online BC calculators (.455 and .422) and I'm considerable off.

As I understand it, air density needs to be factored in.

Can someone help with the correct formula?

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