Ballistic Coeffecient changes??

BC assumes a specific model of bullet shape.
Since your bullet is a different shape, it doesn't work.
So the bug fix is, pretend the BC changes at different velocities.
 
Yes, you are reading it correctly.
No, it wont show up at normal varmint ranges.
 
The only place I know of that will take the multi-BC in to account is Exbal. With this Ballistic Calculator it will take in to account the drop in BC at different range or speed to help predict bullet impact accuratly. In the bullet library of this program you select a Serria bullet and it automaticlly enters what it calls the muli-BC. I have yet to test the accuracy of this function but I will soon. When the weather get better and my gun arrives back from Gaillard.
 
BC is dynamic, it does change with velocity. Manufacturers post the ideal BC at an ideal velocity at a point in time.
 
7 num num said:
The only place I know of that will take the multi-BC in to account is Exbal. With this Ballistic Calculator it will take in to account the drop in BC at different range or speed to help predict bullet impact accuratly. In the bullet library of this program you select a Serria bullet and it automaticlly enters what it calls the muli-BC. I have yet to test the accuracy of this function but I will soon. When the weather get better and my gun arrives back from Gaillard.
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The Bullet Flight application for the iPhone/iPod also has fields for varying BC's, but at the distances I'm shooting (less than 600 yards) I doubt it will make any difference.

That and the fact that Hornady only publishes 1 BC per bullet... and I'm only shooting AMAX and VMAX at the moment.
 
BC is a dynamic variable.
I would guess all bullet manufacturers have an interest in internal, external and terminal ballistics. Sierra, has a BIG interest/knowledge of external b. Hence the furtherthing info. you have read.
 
scott_r said:
How are these calculations made? Seems pretty complicated :confused:

Cheers!!
Click to expand...

Basically speaking BC is determined by multiplying the SD by a form factor, although clearly there is more to it than that as variables such as velocity and elevation influence the numbers. When Sierra moved the location of their test facility, they made changes to their published BC's.

The best way for a shooter to determine the BC of his bullet is to shoot at longish range (300 yards should do it) and compare his bullet drop with the trajectory from a ballistics program for that velocity, elevation, and meteorological conditions. This would be helpful if you were to create a corrected drop table for your own rifle and load.
 
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