Abstract: The assumption of rigid projectile is usually employed to study the penetration/perforation of EPW. It is well known that only two dimensionless numbers, i.e., the impact function I and the geometry function of projectile N, dominate the whole penetration process. The present paper further declares the available range of I and N of EPW, which are likely to be applicable to design the projectile body. The analyses on the compress/stretch and bending of projectiles are conducted to obtain the limit thickness of the cartridges. The minimum thickness of the cartridges and the maximum obliquity angle of projectile, without any bending failure and damage, are formulated in the case of hollow and slender missiles penetrating into concrete targets at different initial velocities. The weakest location of projectile under oblique impact is also predicted. Some suggestions are carried out to define the thickness of cartridge, the local strengthening and the weld locations.