Determine ballistic coefficient of projectile?


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cpileri
December 9, 2010, 11:12 PM
Is there an online program, or a real-live person who specializes in such things; who can determine the ballistic Coefficient of a bullet if its shape, size, weight, composition, and all dimensions are known?

Can anyone point me to the correct link or person?

Sincerely,
C-

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Ol` Joe
December 9, 2010, 11:47 PM
Call Sierra and talk to one of their Techs. I`m sure he can point you to the formula or tell you how the factory goes about figuring theirs.

rg1
December 10, 2010, 12:01 AM
Only way to find out for sure for an unknown bullet is to use two chronographs, one at the muzzle and another downrange at a specific distance. By taking chrono readings of velocity at the muzzle and downrange you can compute BC's. Don't have the formula and you'd need to be pretty accurate to not hit the chronograph downrange. Now if you have a bullet from a known manufacturer, they can usually give you BC's ranges for your bullet.

Zak Smith
December 10, 2010, 12:04 AM
There are two books that touch on it: Rinker's basic ballistic books, and McCoy's tome on external ballistics. The new Litz book might cover it as well. There are computational "rules of thumb" that work for certain geometries; however, as rg1 posted, the way to get true real life BC values is to use radar or chronographs.

rg1
December 10, 2010, 12:22 AM
A simple but very good ballistic program is PointBlank Ballistics with a free download from here: http://huntingnut.com/index.php?name=PointBlank
The program has a bc calculator but you still have to have muzzle velocity and 100 yard velocity for your bullet. Click on Misc Functions for the bc calculator and other functions. A very interesting program and free from HuntingNut. It downloads to a file that I store in my documents folder. Click on the Scope Crosshair file to start the program.

JimKirk
December 10, 2010, 08:32 AM
Brian Litz has lots of work on BC.

I would look at this link... lot of good reading and some BC calculaters about middle of the page.....

http://www.jbmballistics.com/ballistics/calculators/calculators.shtml

Jimmy K

rcmodel
December 10, 2010, 11:16 AM
Every bullet manufactures reloading manual shows the SD & BC for every bullet they sell.

rc

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