The reason for variable BC...
Form factor, each bullet we use has a form factor that is calculated by comparing the attributes of any bullet to the standard bullet that was used to model the G1 or G7 BC.
The closer the bullet is to the form factor of 1.000 the more closely the trajectory of that bullet will be to the drag model that is used.
Because the G1 drag model is based on a flat based bullet a more rounded ogive etc... than that of your typical VLD type bullet the form factor for the VLD type bullets end up being significantly lower than 1.000 when compared to the G1 standard model, meaning less drag than the model predicts. When you put the G1 BC for a VLD type bullet it is predicting that the bullet has the same amount of drag as a bullet with the form factor of 1.000 so the BC's are adjusted at different velocities to make up for inadequacies in the comparison.
Last edited by heavywalker; 06/21/17.
