>If muzzle energy is such a bad metric, then what do

>you propose? Velocity? Bullet diameter? Bullet

>weight? Bullet design? Any one factor, without

>the others, leads to obvious nonsense.

Yes–all of the above!

As long as we must calculate “knockdown power,” I like the WAVE formula discussed in the Mel Tappan classic, “Survival Guns.”

W x A x V x E

weight (more correctly, mass) x caliber cross sectional area x velocity x bullet efficiency

Bullet efficiency is 1.0 for a non-expanding bullet like FMJ and as high as 1.25 for a good expanding bullet.

Note that this metric is proportional to the square of the caliber (pi x radius ^2) This seems to be a better predictor of killing power than energy, which is proportional to the square of the bullet speed (velocity).

There are other similar formulas but WAVE is easy to remember.

]]>Thanks again for posting, and for reading the Books blog!

Corrina ]]>

If muzzle energy is such a bad metric, then what do you propose? Velocity? Bullet diameter? Bullet weight? Bullet design? Any one factor, without the others, leads to obvious nonsense.

It’s a well known fact that .223 Rem is widely used for coyotes. Would anyone recommend 22lr for that role? It’s the same caliber and weight as .223; only its energy/velocity is different. Deer are taken with .357 Rem Mag, but would anyone recommend .38 spcl target loads for the same role? I mean, they fire the exact same bullet, so they should be equally capable, right? The only difference is their velocity and their energy as it relates to velocity. Caliber and weight alone are not enough.

Is a bigger bullet better? Generally yes, but it’s a little complicated. Increasing bullet size without increasing weight means a large round-nose bullet with a poor ballistic coefficient and poor penetration in the target. Maintaining sufficient penetration requires either increasing velocity (same weight) or increasing weight (same velocity). Either solution means increased muzzle energy (and recoil).

Characteristics of a perfect cartridge:

a large caliber to damage as much tissue as possible

a heavy bullet for deep penetration

a high ballistic coefficient for long range

a high velocity for range and penetration

A cartridge like .50 BMG would satisfy all of those requirements, but it’s not exactly practical to drag through the field.

Is energy everything? No, it doesn’t account for everything but at least it considers multiple factors. That’s better than simply looking at a single factor. If someone has a better metric, please provide it.

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