There are lots of things that influence shell pen and whether or not you get full or partial pens, the major factors being: >Raw Shell Pen Values (influenced by shell weight, shell type, propellant, gun size and barrel length) >Ballistics of the Shell (influenced by shell weight, shell type, propellant, gun size and barrel length) >Armor of the Enemy Target (strength, thickness, any sloping/rounding) >Angle of Impact I don't know the specifics of your situation (what bar