Re: Anyone ever hear of the 30 FBI ?
Sorry guys, if the bullets have the same BC, drop and drift are the same. Drop is a TOF issue, Drift is essentially TOF as well but is computed with a component known as lag time. That is the difference between TOF(vacuum) and actual TOF. Lag time is a measure of the effects of drag on the projectile, and thus reflects BC or Coefficient of Drag. The term 'Drift' is misleading in the context of this discussion as what is actually occurring is a deflection. If you'll work the equation a bit you'll see that the bullets are NOT drifting, and in fact resist that quite a bit. From memory, and perhaps not correct: D=wind velocity(fps)/T-Tv where Tv is vacuum time, T =actual TOF.
As to denser core materials, yes, they have a higher BC for a given length and same form, or same BC for shorter projectile. The concept has great merit for many reasons, no doubt some I haven't considered. In any case however, BC is BC, regardless of material of construction.
If you have the time, get a copy of Robert Rinkers book, "Understanding Firearm Ballistics".
[ 08-11-2003: Message edited by: MAX ]