RE: Not for weak stomach!
I shoot stuff- unless you shoot 50s in competition, I suspect I've fired more rounds out of a 50 than you have and more than most. I'm a competitive shooter and shoot a lot. I've yet to see anything impressive out of a 50. Of course I have not shot any animal at 100 yards or less with one(MV is not impressive and more speed offers more destruction) and have only shot out to just under 2000 yards(hard to find clear/safe ranges past that point) Oh sure you've probably seen that pic on the net of the head shot. Yep you hit the head with a big or high speed slug it'll do things like that with the right projectile. But under normal circumstances this wound is not gonna come from a 50. As a disclaimer I have never shot amax projectiles in the 50. I have shot a ton in the 223 and at mid ranges they expand but are not explosive.
Last thought-- now that we are saying its an entry wound, that seems tough to swallow. Though I shot a buck in the neck with my 300 and 180 partitions. I had a hole about half that size, large enough that the taxidermist could not patch it. That bullet did not even penetrate the spine, though it offset the vertabrae enough to sever the cord, the bullet IE what was left of it was sitting against the bone. I suspect that in my case the hole was not as large upon entry but that all the bones and frags could not go out the back side and therefore they went in, and turned around and came back out. Sorta like and entry and exit combined. Sure had a lot of frag holes in the hide that appeared to come from inside out as the hair was not clipped off like an entry wound where the frags came out. And considering that one should only have one entry wound, and no frags till after penetration was effected.
Hard to believe, yet its very possible. Its one of those things, unless you've hunted long enough and seen enough deer shot, stuff like this seems like BS. My only advantage over others is that I guided on a large ranch for a number of years. I was there all season (3 months) in which time we generally harvested over 300 deer each season. With that experience and being that I normally helped skin and gut some amount of deer each nite, you see a lot.
Want to really call BS? I've bowhunted long enough to have seen an entry and exit wound on the same side of a deer with an arrow. Went in left side, came out left side. How can that happen? Only through deflection upon entry though most will call bs. Doesn't bother me. Or the one my brother in law shot from in a tree stand, behind the front leg(downward angle shot) and the arrow exits the TOP of the neck(severe u-turn also)
For all those that call BS, anything can happen. Just because you haven't seen it don't say its impossible. And while I'm at it, it could easily be a fake, doctored photo also.
Actually it really doesn't matter in the end. Who cares. It was an interesting photo. And as noted if its real, then I'd go back and look at my choice of bullets closer. Much like my 300 experience. It was my chosen Elk load if I ever got lucky. I expected to quarter an elk with no problem. Yet it failed on my deer and on a nilgai the same load did not penetrate impressively from an angle either so I swapped out to Barnes X which will do what it needs to and I'm lucky I never tested the original load on an elk.
Jeff