How to Calculate BC from Labradar Data?

Tested FX 81 gr 357 pellets using a Labradar and the Pyramyd air calculator I’m getting BCs between 0.036 and 0.040 ( 50 degrees out, 1400 feet elevation, average muzzle velocity 847 fps (out of my Impact 0.35) according to Labradar, 855 according to FX chronograph.)

Anyone know of a way to enter all the data (speeds at various distances that Labradar provides, averages over a whole shot string) rather than entering the speed at two distances for all combinations? Seems like 0.036 to 0.040 is a pretty big range of uncertainty and averaging a bigger data set might reduce the uncertainty.
 
BC will change for the pellet as it slows down down-range to the target. It's really a differential equation with respect to velocity. If you calculate BC with velocity at the muzzle and velocity at the target, you actually get a something like an average BC for the pellet traveling that distance with the starting velocity from your gun. If you want more accurate BC at specific distances (for your pellet and speeds), you'll break your distance up into smaller sections (i.e., at each point you are measuring the pellet velocity) and calculate BC for each section - using the velocities at the start and end of that section of projectile travel.

If you have a string of velocities, you can certainly average those - but only average the ones recorded at the same distance from your muzzle. Then you can take those averages to calculate your BC between each stretch of measurements as the pellet moves downrange.

-Clayton


 
You can enter multiple bc’s into StrelokPro if you want to.Bit of work in setting it up. 
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