I was hoping for some detailed information about ballistics and its penetration capabilities through various types of building materials or something like that. Instead, he makes a bunch of contradictory assertions why you should do one thing, but doing that one thing really won’t result in a better outcome for you.My understanding is that anything that reduces the energy of the bullet will reduce its harmful effects when it hits flesh or bone. Window glass isn't one of those things, unless it's inch-thick window glass.