Courtesy of G-Tex, of CivDiv Designs fame, a solid and user-friendly ballistic calculator available online.
Q: Why do we need this?
A: It’s simple. If we can produce a table showing point of impact versus point of aim, for any round and load we care to choose, at a given distance, we can set out the BZO that fits our situation and zero more effectively on the ranges– that is, the facilities– available to us.
(Hint: ammo manufacturers readily supply ballistic coefficient values.)
And therefore we can take a step closer to first round effective hits on target. And we get more value out of the time, and rounds, expended.
It’s all about knowing your rifle and how it performs at given ranges.
None of us practices as much as he (or she) would like. So, use the reliable predictive tools at your disposal to prepare you for the shots in the field.