Bullet proof vest.

Bob.
I see you did have an interesting weekend. Yes the .223 will pass through being very high velocity and pointed bullet. The vest are designed for handgun bullets at a range a police officer would engage a perp. The weave of the material is designed to rapidly slow the projectile down while it mushrooms on the vest for the ones that will do that. The 40 I am guessing was traveling faster that the 45 but the 45 being heavier showing more reaction (kinetic energy) They do help stop a handgun bullet but not the transfer of energy that's why police that had their vest on and had been shot have had injuries from being badly bruised to broken ribs and the wind knocked out of them.