Even on a properly placed shot you may not get a good blood trail. I've seen deer hit in the Lungs that did not bleed a drop, a-lot of Fat in the Deer caused the entrance and exit holes to plug up. Some spue blood other's drop a few spots and some dont bleed, it's just how it goes. As mentioned above a properly placed shot in the Lungs Heart Area is all you need for the Animal to not go too far.
You can shoot 5 Deer in the same spot with the same ML and Bullet and get 5 different results.
(BP)