I am working my way through this thread and have really enjoyed it so far. I killed my first deer with a 5.56 (RA556B), and each year give my friends different rounds to hunt with (One year it was 70gr TSX, one year it was 75gr Gold Dot, etc). So far we have harvested deer with:
RA556B (The entrance was more impressive than the exit, the deer ran 75m with minimal trail and died. Interior damage was "what one would expect")
75gr Gold Dot (Blood everywhere, deer stumbled around in a stupor an died. Interior damage was "worse than my .30-30!"-Friend)
70gr GMX (This one was variable. My friend shot a deer at about 120m and the projectile ice-picked and tumbled. It was a 5.56 Black Hills loading, and fired from a 16" gun. The deer had a minimal reaction to being hit and required follow-ups). (I shot a deer with this round from a 14.5" gun at 27m, and there was tons of blood, the deer ran about 80m, and literally hit a tree. The damage could be described as "the same as I see from TMK in this thread".) I have also shot a deer with this round at 74m, and the deer died instantly as it was a shot that intersected the spine. Damage was reasonable. In water jug testing, I noted that this round from my 14.5 would often shear the petals off. I believe that this round is "brittle" and either fragments or fails to expand, with a very small "goldilocks" zone where proper expansion will occur. My 74m deer may have been within that zone.
70gr TSX: This one has reliably just killed stuff. No insane damage, no poor damage, it just tends to poke 0.5-0.75 inch holes through things.
I have bought a case of 77gr Black Hills TMK this year to try out. I found it for $700 shipped, and figured I'd snag it.
