They will all exhibit a sharp drop in BC (or rather an increase in drag) as they approach Mach 1.... It is the shape of that curve that differs between pellets.... and even that is really only a measure of how well the Drag Model (eg. G1 or GA) you use to calculate the BC matches the pellet.... The BEST way is to develop your own drag model for your specific pellet and gun combination.... not really practical for most.... However, I think with the new Doppler Radar sets now available, we at least have a chance of developing a better drag model for pellets in the Transonic Region (Mach 0.8-1.2)....Bob