InfraRED,
I tried your setup once, sorta. Our phone books are but 1/4" thick and I couldn't steal enough of them to make a wet pack.
What I did have plenty of were my wife's various glossy magazines. All taped together and soaked over night they provide a very tough medium to shoot into. Too tough I guess. I got hardly any penetration with 45 or 357 ammo of different weights. Just to show those magazines who was boss, I shot a pack of them with a 243 soft point. It disintergrated within an inch.
Don't use soaked women's magazines. They could double as soft body armor.