
552 Ballistics: Theory and Design of Guns and Ammunition
These are empirically derived values. In Equation 19.3, d is the diameter of the actual pro-
jectile, d
6
is the diameter of a 6 mm projectile (in case you want the units of d in a differ-
ent system), and U
6
is a characteristic velocity for different materials determined through
experiments with a 6 mm diameter projectile. The parameter a in Equations 19.1 and 19.2 is
a function of the projectile type and the angle of attack of the projectile.
The stability criteria developed in Part II of this book work fairly well for behavior in the
human body. As stated earlier, the density terms must ...