I've seen both good and bad blood trails from .264 and .308 holes, from a plethora of bullets at various impact velocities.
The only constant I have seen is that snow makes the sparse blood trails easy, though the only times I have needed one is when I make a poor hit.

This was not a poor hit via 200 grain Speer Grand Slam (old style) at ~200 yards from a .300 H&H. Impact velocity what...2400ish FPS? That right side would be the exit hole, right at half way up the body, tight behind the shoulder. Notice there is no blood to the left (entry hole). This I would guess is due to the expanded bullet making a bigger exit hole and "pushing" everything that direction in the body cavity? Sometimes I see blood on both sides and sometimes just one. I can't explain it.
[Linked Image from i.imgur.com]


Discuss.