FMJs= very good penetration+ very little tissue damage.

A little anecdote:

Last fall I took a friend out shooting and let him shoot my M1 loaded with ball ammo. He shot at a pumpkin (uncarved) at 100 yards. I expected the pumpkin to explode when hit, but after 6 shots, the pumpkin did not move. We took a look at it, there were 6 bullet holes that went completely through the pumpkin- the holes were actually much smaller than the bullet diameter also. About the only use for non expanding bullets is Cape buffalo and Elephants, where smashing through skulls and massive bones and muscle is needed to hit a vital organ or brain.