Hi, I got an balistics app and it want to know the hight on my scope, where do I measure from? And where Do I get the BC of the zan 20gr ?
Help with input on calculator
- Thread starter Gambler
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For scope height over bore I like to use the tin foil method. I think its a little more accurate than just using a ruler on the actual scope. Here is a link. It works best with lots of light. Like outside in the sun.
airgunaccuracy.wordpress.com
Chairgun and “Scope Height”
I hear a lot of people complaining about the ballistic software Chairgun not being in line with their real world results. But in my field target rifle and scope combo’s it has improved to bei…
airgunaccuracy.wordpress.com 
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To determine the true BC of your slug you will need to shoot it over a chronograph. Shoot about ten shots and get an average muzzle velocity. Then move the chronograph to a know distance downrange and shoot ten shots over it again for an average. I usually do this at 25 yards and again at 50 yards. Depends how much you trust shooting over your chronograph at longer range. Once you have those velocity numbers your ballistics program should be able to determine your true BC for you. I say true BC because the BC is fluid is influenced by environmental factors. The manufacturer can supply a BC but it is only so accurate. Elevation, temperature, humidity and even your own barrel will greatly affect the actual BC.
Kenny
Kenny
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