No Need For Speed?
For many years, velocity has been considered by many to be paramount when judging a bullet's killing ability from a given cartridge. Bullet energy has long been accepted by many gun writers - and thus by the shooting public - as the standard that cartridges are measured by. And while energy can be useful when comparing cartridges, it's my opinion that it is far overrated, and only minimally useful in determining whether a bullet will do its job once it reaches its target.
TKO: A Better Measure
A better measure, one that's gaining popularity as more shooters learn of it, is known as the Taylor Knock Out value, or TKO. TKO takes into account bullet weight and diameter, as well as velocity. Energy only considers mass (weight) and velocity, without considering a bullet's diameter - and diameter can and does make a big difference in terminal performance.
There is no perfect way to quantify a bullet's terminal performance - I want to make that clear before I go any further. I think TKO does a better job of doing so than foot-pounds (ft-lbs) of energy, but neither is ideal.
I have read recommendations that in general, a hunting bullet should be traveling at least 2,000 feet per second (fps), and carry at least 1,000 ft-lbs of energy to ensure a clean kill on a deer-sized animal. This is fine and dandy and may make for interesting reading, but here in the real world it's just so much moot BS.
I have shot a good number of deer with a 44 magnum carbine, using 240-grain jacketed bullets - more than a dozen, at ranges varying from ten feet out to 115 yards. Never lost a one, even when my hits were less-than-perfect. Devastating wound channels and deer that drop on the spot are rules rather than exceptions with this gun and cartridge. Most of the time I never recovered the bullets, because they went all the way through the critter.
Here's the kicker - that carbine has less than 2,000 fps of velocity at the muzzle! Out at 100 yards, which is very nearly the end of that cartridge's effective range, velocity of its stubby, blunt 240-grain bullet is only about 1380 fps - yet it kills deer dead, reliably and repeatably. The slug still meets the 1,000 ft-lb requirement at 100 yards - but just barely.
I give this example only to illustrate that minimum velocity and energy requirements are not things you can hang your hat on. They are arbitrary at best, and grossly misleading at worst. Energy/velocity figures can work well when discussing only a given class of cartridges, but they are not the be-all, end-all definer of bullet performance that many believe them to be.
Speed Isn't all There is
Is velocity important? Sure it is. A faster bullet gets to its target faster than a slow one - that's a no-brainer. Is velocity everything? Nope. You must have a bullet of suitable construction - something that no formula does (or can) take into account. You must also have a bullet of adequate diameter and weight to give your target an efficiently killing wound. Key word there is efficiently. The tiniest bullet wound can kill, but we want our game to expire quickly - or in the case of self defense, we want to immediately disable someone attacking us - and so the bullet used must be efficient in doing its job.
Can we Measure Killing Power?
Okay, so how can we quantify with formulae the ultimate hunting (or self-defense) cartridge? Well, we can't. It's that simple - every method of comparison falls apart when taken to extremes, and the old adage that there are exceptions to every rule is very, very true in this context. (continued)