For the whole bullet, the Magnus effect (which arises from the
boundary layer interaction of the inclined and rotating body with the flowfield)
results in the Magnus force FM 
which applies at its centre of pressure CPM. The location of the CPM varies
as a function of the flowfield conditions and can be located either behind
or ahead of the CG.
The figure above assumes that the CPM is located behind the CG. Experiments have shown that this comes true for a 7.62 x 51 FMJ standard Nato bullet at least close to the muzzle in the high supersonic velocity regime.
