Re: Predicting a Bullet\'s B.C. ??????
The best way to find a true BC is to go out and do a firing test.
1. You know the velocity
2. You can look up atmospheric data on the web or use a handheld field station.
3. You know the ranges to your targets. 400, 600, 800, 900, 1000 yards.
4. Write down the amount of clicks you had to use to hit dead on from zero. Or Mils, MOA's or whatever method you use to compensate.
5. Go to your software and plug in all the known variables and manipulate the BC until the output matches best.
If you need a place to start, always start with G1 and the manufacturer's published BC. Start at 300 yards (for a 100 yard zero or 400 yards for a 300 yard zero) Go from there.
In the Reloader's Archive, there is a shooting log that converts clicks to inches of drop at range. With that, you then go to the ballistics output page and adjust the BC and drag function until all the numbers match. Once a drag function and BC is set, these stay constant for the purpose of the calculator. From there atmospheric data is changed and the results are displayed.
Some BC calculators can do pretty good, but none will be 100% and even more none will be 80% or better 80% of the time. The best is real world. BC's change from rifle to rifle to so once you find a true BC for a given load, it doesnt mean that it will be the same or even close for that matter in another rifle.
I would say the The Reloader's Archive is "THE" software, but I cant cause I am bias. [img]/ubbthreads/images/graemlins/crazy.gif[/img]
Hope that helps!
Long range shooting is a process that ends with a result. Once you start to focus on the result (how bad your last shot was, how big the group is going to be, what your buck will score, what your match score is, what place you are in...) then you loose the capacity to focus on the process.