Killing Power: Bullets and Arrows
By Chuck Hawks
The concept of impact energy and "killing power" are pervasive throughout the literature and come up in just about every discussion on cartridges. The size of the game animal also factors heavily in cartridge choice. People routinely shoot and kill deer (for instance) with a 400 grain arrow and a "muzzle velocity" as the arrow leaves the bow in the low 200 fps range. Why is it that a rifle with 600 ft. lbs. of energy downrange is considered too weak, while in the archery world, knockdown is not even discussed and the only issue is accurately hitting the lungs?
That was the question posed to me and it is a reasonable one. Understand up front that I am not an archer, I am only a shooter. However, it is my understanding that arrows kill by cutting blood vessels, like a knife or sword thrust, only at longer range.
Arrows are very long and skinny and have terrific sectional density to aid penetration. They are far better than any bullet in that regard. It takes much more energy to power a typical hunting bullet, given its much lower SD than an arrow, through flesh and bone. (Bullets work by brute force.)
The bigger and stronger the animal, the more bullet energy is required on target and the "tougher" (less expansion with higher weight retention) the bullet must be to ensure adequate penetration. The skin of what we call thick-skinned game can literally be inches thick and the shoulder of a bison or grizzly bear is a heck of a lot larger and harder to break than the shoulder of a whitetail deer.
After impact, bullets also cause severe bleeding, but have a much wider wound track. The permanent and temporary wound cavities (note the high speed photos of bullets hitting gelatin blocks) destroy or damage a substantial amount of tissue on their way through the animal. This introduces other wound mechanisms, such as shock to the nervous system and damage to, crushing of, or even cessation of operation of vital organs not directly touched by the bullet.
It is not unusual for a CXP2 class animal hit with fast-expanding bullet to fall dead on the spot, with "four feet in the air." A powerful bullet with sufficient kinetic energy can stop or turn the charge of an elephant or lion. I bet those sorts of results are very uncommon when an animal is hit by an arrow. Shoot an alert, angry and dangerous animal with an arrow and my guess is that you had better arrange to stay out of reach until he bleeds out.
The trauma (in addition to simple blood loss) caused by a bullet's impact is what introduces "stopping power" (a term used in reference to self-defense firearms), or "killing power" (usually used in reference to hunting rifles) into the equation. This gives firearms a big advantage over arrows in life or death situations and also helps to deliver quick kills to game animals, which should be the goal of every hunter. I don't want my deer to suffer fear and pain for one second longer than necessary, so I always try to use an adequate firearm for the job at hand, one that can cause an almost immediately fatal injury.
Copyright 2012 by Chuck Hawks. All rights reserved.