Originally Posted by Hunter15
... I have heard of using multiple BC's entered into a program and have the option to do so but am unsure of how multiple BC's work....
If I may... (and there's many on here who understand this much better than I do...)
I seemed to have this problem with a friends 22-250. My calculations were good to 350 or 400 yds but at 600 or so the bullets were hitting quite a bit low. As a bullet flies downrange and decreases in veloctiy it also loses BC value. This is one reason that on Sierra's website they list multiple BCs for a given bullet, based on the veloctiy.
EX: A .224 cal 55gr Sierra BlitzKing has a BC of .271 @ 3100 fps and above. But they also list the following:
BC= .264 between 3100 and 2550 fps;
.250 between 2550 and 2050 fps;
.236 between 2050 and 1800 fps;
.224 @ 1800 fps and below
For my friend's 22-250 I had an original starting BC which was good from 0-400 yds and then a lower BC which was valid from 400-600 yds, etc...
Hope that made some sort of sense... maybe someone with more experience will chime in as well...