"'Assault Rifle' vs. The Common Backpack: Are the AR15, AK47, and SBR MP5 Defeated by a Mere Bookbag?" James Reeves of The Firearm Blog Youtube Channel (TFBTV) decided to find out. The 9 mm from an MP5 was, not completely unexpectedly, easily blocked by a backpack full of magazines, papers, and a few textbooks. Surprisingly, at least to me, is that the 7.62x39 and 5.56 NATO rounds were also stopped, although they went through quite a bit more paper. Both, however, were defeated by the Criminal Law textbook at the very back of the backpack. (Reeves, as some of you may know, is a lawyer). I suspect that a text book on bankruptcy law would have been even more effective since the subject matter is more dense!