What a buncha idiots. Well, one is now dead, but still.

Using the equation below with the assumptions noted, it’s possible to estimate how far ammunition of that type should penetrate a material with that density:

3cm bullet with density 8000 kg/m3
Book with density 400 kg/m3
speed on impact 500 m/s
0.03 * (8000 / 400) * .5 = 0.3

That’s 30 centimeters — nearly a foot. Intuitively, that’s about what I would’ve expected. Books aren’t that dense and having shot books and at (abandoned) cars before, I know bullets go right through them like they were nothing, even from a handgun.

Assuming an average thickness of 4 inches, the “victim” would’ve needed to hold at least three volumes of the encyclopedia up to his chest to be reasonably sure of no penetration. I’d recommend four, or better yet not doing the stunt at all. But it’s too late for all that now.

Or he at least could’ve looked up some of this information in said encyclopedia beforehand.