....A hatton round is not a solid slug....
Hate to disagree R44...... but it's actually a powder compressed into a solid. If it wasn't a solid, it wouldn't be able to effectively dissipate the kinetic energy needed to attack the hinge/lock.
What it is however, is frangiable, meaning it breaks up on impact, but after dissipating the KE - thus making it safer for those sat behind the door.
But, I can guarantee....... it's solid
