Cartridge Hitting Power: What Kills the Best?

Two primary criteria we use to compare and judge cartridge lethality are bullet velocity and kinetic energy. In America, speed is expressed in feet per second (fps); energy in foot-pounds (ft-lbs), one ft-lb is the force required to move one pound the distance of one foot. By themselves, neither kills game. This is only done with bullet performance, applied in the right place.

However, velocity and energy are important. Velocity, coupled with bullet aerodynamics, determines the trajectory curve. Energy overcomes resistance, thus its what does the work of disrupting vital organs and putting meat on the table.

The mathematical formula that derives kinetic energy (ft-lbs) uses squared velocity. Bullet weight is taken as is, so as velocity increases, energy goes up exponentially. In any given cartridge case, lighter bullets can be driven faster than heavier bullets. So lighter bullets may show higher energy figures than heavier bullets. This is probably the basis for the old campfire argument about which is better: Lighter bullets pushed fast, or heavier bullets moving slower?

To some extent, it depends on what you’re hunting. It’s critical that your bullet is of sturdy enough construction to penetrate to and through the chest cavity of the game and cause damage hunted. Typically, we hunt small varmints with light, frangible bullets pushed very fast. We don’t need penetration, and if the bullets come apart, there’s less chance of ricochet.

How Much Kinetic Energy?

Exactly how much energy is needed is impossible to say. Great gunwriter Colonel Townsend Whelen theorized that we should have 1000 ft-lbs at the animal for deer-sized game. A big bull elk is twice the size of any deer, so I’ve theorized that 2000 ft-lbs makes sense for elk.

I think these are good guidelines, but they are not locked in stone. With its 200-grain bullet at 1190 fps, the .44-40 produces 629 ft-lbs. If Whelen’s 1000-ft-lb rule was absolute, then the “gun that won the West” could never have killed a deer. With its 405-grain bullet, the original .45-70 load was rated at 1330 fps, producing 1590 ft-lbs. If my 2000-ft-lb rule held water, then the .45-70 could never have taken an elk. We know that it has, along with untold numbers of bison.

The .44-40 and .45-70 were black powder cartridges, still held to mild original pressures. Since velocity is low, so is energy yield. Even so, both cartridges are legendary, seemingly punching far above their weight classes. Although not squared like velocity, bullet weight is a component in deriving kinetic energy. Not considered in any way is bullet diameter, frontal area. The .44-40 used a .427-inch bullet; the .45-70 a .458-inch bullet. Both are much greater in diameter than the 6.5mm (.264-inch) to .308-inch bullets most of us use for deer and elk. I believe diameter matters in transferring energy, dealing a heavy initial blow.

Would you rather be stabbed with a knitting needle or slammed with a hammer? “Neither” is the right answer because both can do irreparable damage. The hammer won’t penetrate as deep but transfers more energy on impact.

Hitting Power

If velocity, bullet weight, and construction are similar, I’m convinced .30-calibers (.308-inch bullet) hit harder than 6.5mms (.264-inch). The .358 Win is based on the .308 Win case necked up. You could load each with a 200-grain bullet at about the same velocity. Having hunted with both a lot, I’m certain the .358 hits harder. That’s a significant .050-inch difference in frontal area. However, I can’t tell you how much more frontal area is needed to see a difference. I don’t believe there is a noticeable difference between the .25s and 6.5mms (.264); or between the .270s (.277) and the 7mms (.284). In both cases, just .007-inch (seven thousandths) difference.

There have been attempts to quantify the effect of frontal area. Elmer Keith liked momentum (he called it “pounds-feet”). Ivory hunter John Taylor (African Rifles and Cartridges) proposed “Knock-Out Values,” ostensibly based on the stunning blow to an elephant’s skull from non-expanding solids. Hunting buddy Mark Belcher (engineering background, smarter than me) recently proposed considering the complex “drag factor” equation which yields Ballistic Coefficient (BC), modified to reflect resistance in ballistic gelatin, vice air. At the same velocity, figuring in 1.5X bullet expansion, Mark’s calculations suggest a .358-inch bullet has about 50 percent more “terminal drag” than a 6.5mm (.264-inch bullet).

My friend may have something, but it’s tough to be definitive. Resistance in game varies tremendously by the size of the animal, also between the complex matrix of muscle, bone, and organs. And, depending on design, bullets expand differently and at different rates. For certain frontal area matters on game, as does bullet performance.

Unless we’re shooting pachyderms, most hunting with firearms is done with expanding bullets, larger wound channels and more damage to vital organs. However, bullet expansion reduces penetration; the larger a bullet expands or upsets, the more resistance it encounters.

Non-Expanding Solids

On thick-skinned dangerous game (elephants, usually hippos and rhinos), we use non-expanding “solids” designed only to penetrate. On elephants, I’ve seen both the fearsome .600 and .700 Nitro Expresses fail to penetrate, the former with 900-grain solids, the latter with 1000-grain solids. Plenty of energy, but both cartridges are slow. The only explanation: Not enough velocity to overcome resistance to their extra-fat bullets.

So, a bullet must have enough velocity behind it to penetrate into and through the vitals. But too much velocity isn’t necessarily a good thing, because high velocity is the enemy of bullet performance. Pushed too fast, many bullets, especially simple lead-core bullets, can expand too quickly or break apart and fail to penetrate. Designs such as bonded core, dual core, and homogenous-alloy are less velocity-sensitive than traditional lead-core bullets.

Obviously, distance figures in. A 7mm or .300 magnum with lighter bullets (respectively 140 or 150-grains) may be unreliable at close range, but perform well at distance, after the bullet has slowed down. The reverse is also true: No expanding bullet can perform the same at all speeds; expansion is reduced at lower velocities. So, at the extreme ranges some folks are now shooting, there is a risk of poor expansion, with bullets acting like solids.

This is a dilemma. On any hunt, you may expect a long shot, but a close opportunity can’t be ruled out. And vice versa. With fast cartridges, the wiser course is probably to use tougher bullets. Or heavier bullets. As I believe in frontal area, I believe in heavier bullets. Not because I believe they “hit harder.” Energy is what it is. However, if design is similar, heavier bullets penetrate better, even if velocity is lower.

Bullet Shape

Shape also matters. Today, everyone wants distance, so long, streamlined, pointy bullets are the rage. Fine, but not everyone needs range. If you don’t, for instance for black bears, hogs, or whitetails in thick cover, consider loading up with old-fashioned round-nosed bullets. Blunt-nosed bullets transfer more energy on impact and initiate expansion more quickly than sharp-pointed bullets. (Again, knitting needle versus hammer.) The paper ballistics of the great old .30-30 aren’t impressive, but we know it’s taken a lot of deer (and larger game). At least in part because of its traditional blunt-nosed bullets.

When in doubt, get a bigger hammer. Sheer bullet mass covers a lot of sins in bullet construction. The old lead-tipped Sierra GameKing was a simple cup-and-core bullet. Exceptionally accurate, rarely pretty when recovered from game, especially at higher speeds. I’ve used a lot of GameKings in various cartridges. Love the 150-grain spitzer in .308 Win, usually stepped up to 165 in 7mm Rem Mag, and to 180 grains in .30-06. Then on up to 200 grains in magnum .30s. In .30-caliber, a 180-grain bullet is 20 percent heavier than a 150-grain slug. The extra bullet mass ensures deeper penetration, and if the bullet sheds weight, 20 percent more to lose.

Today we know the bullet race isn’t always to the fastest. Today’s super-aerodynamic “low drag” bullets are longer and heavier than traditional hunting bullets. They start slower, but with higher BCs, they will pass lighter bullets that start faster. Although I’m not an extreme-range shooter on game, these heavier bullets suit me just fine. In my .300 magnums I switched to Hornady’s 200-grain ELD-X when it was brand-new, and I’m hunting with 175-grain ELD-X in my 7mm PRC. Like most “low-drag” bullets, the ELD-X isn’t always pretty when recovered, but it works, especially with the extra mass of the heavier bullet.

For close-cover game, I’m usually not shooting a magnum .30 or a PRC. Given a choice, I’ll probably revert to my concept of a big hammer: Maybe one of several medium-velocity .35-calibers like a .348 or .358 Win, lots of frontal area and bullet weight. Not much recoil, plenty of hitting power!

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