Books for wetpack testing?

Thanks to a link posted in response to og's earlier discussion of his wetpack testing

http://theboxotruth.com/

I discovered that my previous attempt to do some penetration/deformation testing with dry phonebooks and newspaper was meaningless: the box o' truth testing demonstrated that bullets acted completely differently when shot into books.

Unfortunately, I used up all my newpaper, and it takes a while to accumulate (who needs to buy newspapers when you have "the Internets"? ). But I found a stack of old computer trade paperbacks for a nickel apiece, so I grabbed some.

I know that the paper used in books has different characteristics from newsprint and phonebooks. The question is whether it's different enough that soaking it won't make it kinda-sorta useful for ballistic testing. I don't care whether the results can be compared to "official" ones: I just want to do some comparative testing of different .38 loads that will give me some rough idea of how they'd perform in real-world conditions. The dry-paper test told me nothing: the jacketed hollow points, e.g., were almost "reloadable" after passing through a couple of layers of corrugated and a couple of inches of paper.

Has anyone tried using wet books and found that it does/doesn't give useful results?

I do have a good supply of 2-liter soda bottles. Would I be better off using those?

Thanks,

Ran

p.s. Any bibliophiles out there who are aghast at the notion of "book desecration" can forget about lying to try to dissuade me: those Internet Exploder and Windoze 95 books are going out to the desert to be shot up. The only question is whether they'll be "giving their lives for science"