What kills an animal dead is loss of oxygenated blood to the brain and major organs.
Drop on spot = put bullet where it impacts major sets of nerves thus rendering the animal instantly unconscious. A bullet and its shock wave through the shoulders impacting the big bundles of nerves in the armpits and front of thoracic cavity ( The HILAR) or impact the spine or brain will cause this. If the bullet also takes out major blood vessels the animal will bleed out before it regains consciousness.
If bullet and its shockwave only connects with major blood bearing organs - ie heart, lungs, liver and major blood vessels the animal will either stand and stagger or run until there is a major loss of blood pressure thus depriving critical organs of oxygen.
Some bullets will cause a bigger wound channel and this more damage to blood vessels so a quicker loss of blood. A bigger is not necessarily how wide the the channel is but its length and volume.
Put a bullet where there is little blood flow, animal will die from infection or may recover.
Bullet, cartridge and how much power doesn’t really matter, shot placement does. If power was critical then why do we use a 1,000 ftlb min cartridge on Roe which way 40kg on the hoof, yet a min of 375h&h with 4,000 ft lbs plus on Buffalo (1,000 kg) and Elephant (7,000 kg). Even the really powerful cartridges such as the 600 NE are only producing 8,000 ft lbs.
An elephant is 175 times the weight of Roe deer, but we don’t use, or gor that matter need a rifle producing 175,000 ft lbs - recoil would be a touch high. Instead many many buffalo and elephant are shot with 375s. Indeed plenty have been shot with 6.5x54s and 7x57s with about 2,500 ft lbs. Put their bullets in the correct place and tye drop on the spot.
