The result of field testing concurs very close to his findings.
Field testing will reveal any anomalies that my conditions have as compared to his.
So, if I use a G7 of 0.324 for a 208gr A-max (this is a Litz BC) and plug all pertinent data into a ballistic program and find that my result is ,lets say, 2 moa different in drop than his then the 'effective BC' in my circumstance is different. If I know the difference then I can account for it.
This is but one of the items used to build an accurate drop chart.
Another example is a 200gr Accubond has an advertised G1 of 0.588 and a G7 of 0.273. The testing I have done indicates a G7 of 0.268. This is most likely due to a lower velocity, slower twist rate than normal (1:11), elevation and atmospheric conditions.
Commenting on relative accuracy of Litz's BC's was done through field testing.
You can do that too, the 'kicker' is you need accurate velocity readings, the rest is math and working the program.
As always, trust but verify.
