I'm definitely not (repeat, NOT) a bullet expert!
But the one hog I shot using an AR-15 was with a Nosler Partition bullet, which I recovered.
That bullet (which weighed only 60 grains) had a somewhat small lead portion, which separated from the rest of the bullet. However, I felt the bullet, in that case at least, had performed well.
PHOTO:
I'm not sure how relevant this is, but the fact that the bullet separated didn't bother me. Maybe it should have, but at present I'm too ignorant to understand why. Not being smart-@$$, probably just showing my lack of knowledge regarding bullets.