[ QUOTE ] How do you find the true b.c. of your bullet? [/ QUOTE ] There is more than one way to skin this cat. One of the many ways is to shoot through 2 chronies spaced some distance apart such as 100-300 yards. Then a ballistic calculator will give you the BC. One other way (my favoraite) is to zero your rifle at a specified distance. 300 yards works near perfect. Then fire your load out to your maximum range and at 100 yard increments between. Then after paying close attention to your real muzzle velocity and the current air density during the test, you can manipulate the numbers in your calculator until the BC and drag function make your chart match the one you just created. Once that is done, you have your BC and you will not need to change it in the program for new ballistics, just the air density.