The FMJ will tumble in flesh, reversing from point first to butt first in its path, I recall about after a few inches travel in the body. That's based on Army Medical Corps autopsies. That is also where they found bullets breaking up on the cannelure. I would expect it to do so on any medium sized critter. Nuff said on that
Will it do it every time? 1 time out of 10? 1 time out of 100? Like I said, I tested FMJs on solid fruit myself, and the results were less than inspiring. FMJ's did minimal damage- a caliber sized entry and exist hole, that for he most part sealed itself back up, even a remington corelokt bullet would do spectacular damage to fruit, but a FMJ would not.
I would expect it to do so on any medium sized critter
There is a good reason why its illegal to use FMJs for hunting in most places- they do minimal damage, even if they tumbled, they would still do minimal damage. FMJs are not a hunting bullet, though I can see using them on small animals like coyotes on down.