Yes you can use 2 chronographs try NOT to hit the second one! I use LabRadar to determine the bc’s of my home made .25 cal slugs and have only tried one pellet;33.95 gr. JSB which computed to a bc of 0.046 using the GA function. Slugs need the G1 function ( can use JBM program), pellets ChairGun. But as others have said bc will be influenced by the velocity range and to a lesser degree gun/barrel. LabRadar will give you velocities over a range of distances and you can choose what velocity band you to measure bc. Of course the 2 chrono method could be used but with more setup time involved. On the other hand Hard Air Magazine website has many bc’s in their ballistic coefficient section and your pellet type may be included.Originally Posted by Magpie palmer
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