the ingall models are not the same as G drag models the g drag model is more updated but you can find the conversion tables, All manufacturers publish coefficients using the g1 model, i am trying to find a table of B.C decay rates for the G models.
my problem is that even with an accurate measurement of the projectile, cartrige, sectional density and the bullet wieght, the results will be using the wrong decay rate therefore the bullet drop, wont be what you see in the field