Active Shooter Backpack Armor: Can M855A1 Defeat Plastic Armor ~AND~ A Book?

M855 will normally punch right through most UHMWPE plates but can it punch through a polyethylene plate with a book or laptop in front? Shot Stop's incredibly lightweight all polyethylene SSB-III-RA2 backpack armor panel is NIJ lvl III rated to stop 7.62x51mm M80 FMJ and is not intended to protect against M855. but we test it with M855 and M855A1 to see if it can stop these rounds with a book or laptop in front of the armor.