I need an info on ballistic coefficient on this projectile?

Update: I have a .177 break barrel rifle. The muzzle velocity for this projectile is around 780 fps.
Update 2: The projectile is 13.43 grain JSB exact monster redesigned. What is the BC?
Update 3: I need the BC because I need to know the maximum range for this projectile. 100 yards approx.
Update 4: @mrBean: maybe you should go out rather than "telling a story of your childhood".... and yes I have been googling all day to find this precious "math".
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