A finite target perforation limit means that the projectile reaches the rear
face of the target and spalling opens the penetration channel. The penetrator residue
will have a length of one to one and a half diameters. In experiments the residue sticks
in the exit crater or drops to the floor in the immediate vicinity of the target. The result
is observable at the target site, whereas a semi-infinite target first has to be cut up laboriously.
The perforation limit is primarily determined at an oblique plate.