Thats a new one on me as well. Interesting stuff.
I've seen a few bullets that have broken the skin but haven't come right through, but none have been backed out like that.
I can remember a few years back shooting a big billy goat as he ran directly away along a game pad.
I was using a 360 No2 double and 286 gn Barnes X bullets.
The projectile went full length of his body and was almost ready to drop out of the exit hole in the skin.
You could see this bright gold thing in the hole which turned out to be the nicely mushroomed bullet.
The size and shape of the hole though showed that it was still travelling front forward.