Ballistic Coefficient

[lorvan]

Excuse my poor English.
I try to calculate a ballistic traiectory using ballistic software.
But, I have seen that ballistic coefficient change with the bullet speed.
Nosler give us only a ballistic coefficient, but I know that ballistic coefficient is a little different at various speed, ad so at various ranges. How may I do for calculating a true traiectory for shooting at 700 yards with my sauer 90 7 rem. mag. ?
I have used the Peja formulas, that introduce a coefficient for degrade the ballistic coefficient, but it do not works very well...
Anyone know the answer?

Lorenzo

Florence - Italy -

 

[Ol` Joe]

The BC given in most books for a bullet is a estimate or average over the flight of it and not a fixed number.
The temp also affects the trajectory, and the burn rate of the powder which also changes the initial velocity. The best way I know of to see what the true BC is for your bullet under your conditions is to shoot and record.