Ballistic program not matching actual

[caryo15]

I've played with the velocities and BC and have gotten close, 2775 fps with .420 BC. I've herd the published BC's can be off, but this much?

With the adjusted inputs, will wind drift be close also? Will changing atmosphere conditions be as close (a linear change)?

The purpose of purchsing exbal(from reviews here), pocket pc and the kestrel is for a first shot hit at different ranges in different weather conditions.

The difference between the two rifles was very simular. This makes it appear like the program.

 

[Loner]

168's in a .308 past 900 aren't a good idea. Especially at lower altitudes. They transition
and not very well at times. Try your data leaving the stuff past 800 out of the equation.

 

[bigngreen]

Change to IPHY adjustments, .427 BC and 2814fps and see what you think.

 

[Loner]

I missed the lupy scope part. I would use iphy which puts it at 36.6 iphy @ 1000 in jbm using den.alt. and .427 bc in a g1. Sierra uses a dual bc number and it's apparently not for little more than advertising. I would suggest shooting a 155 berger or the 155 Scenar
past 900 with a .308. Even the 175 smk does better than the 168's. Your mach is around
1142, and your bullet is 1190 at a 1000. That's too close imho.