I do not like phone books either, for a variety of reasons. I have shot many different materials but finally settled on the jugs and boards. The recovered bullets look very much like bullets recovered from game and the results are consistent from bullet to bullet.

I'm not sure if there is really anything that can "duplicate" animal bodies...except animal bodies.

That testing {for service pistols} I've done on sheep and goats, but it is no real help either since getting two bullets to hit the same amount of bone and muscle is really difficult. However, my stock shooting at least put to rest the notion of the existence of "stopping power" among service pistol catridges.

A homogenous medium like the wet phone books isn't a "bad" bullet testing medium. It is, however, in my experience, very easy on the bullet and makes for classic mushrooms where classic mushrooms may not be created by the impact with game. The jugs & boards media is far better in this regard.