I experimented with some Federal 124 gr +p Expanding Full Metal Jacket (EFMJ) rounds. I fired them into two Yellow Pages books from a range of 7 yds (a reasonable self-defense range).
I fired about 24 rounds through two phone books....of those, only two of the bullets stopped in the books. The rest penetrated all the way through (1200+ pages). I didn't have the opportunity to try wet vs. dry books to see if there was a difference.
I fired a total of 250 rounds from five pistols (Ruger, Glock, Sig, Steyr and Walther). Not a single hiccup or problem. All in all, I feel pretty good about these rounds for home defense.
The following photos show some of the results.
Here are two mushroomed rounds next to an unfired round. They expanded to approximately 1/2" diameter.
Here are two mushroomed rounds
Here are two mushroomed rounds plus a third round that was severely deformed.
The following series of photos show the expansion of one of the rounds as it passed through the phone book. Each photo indicates how many pages of the phone book the round had penetrated at that point.
Exit hole - 675 pages deep