How to Select a Hunting Cartridge, Part 1: The Basis for the Selection.

Dana Barrett (Sigourny Weaver): “What is that thing you’re doing?”1

Professor Peter Venkman (Bill Murray): “It’s technical.”1

1 = from Ghost Busters, 1984

Many posts on hunting forums indicate hunters with a deer rifle capable of more “oomph” than a 30-30 Winchester or a 35 Remington believe it can kill anything.  “Calibers” (chamberings) capable of uber-energy produced from the Sidewinder missile-like velocity of a low sectional density, high-BC bullet that result in DRT from presumably “hydrostatic shock” on a 150-pound (68 kg) animal are revered as if Thor walked among us, punishing non-believers. The implication is that no animal at any distance is safe from such a “caliber”.  Some defend that notion with the same ardent zeal as a Ford pickup truck owner that would rather push it than drive a Chevy. Such is the stuff of human nature.

I am not immune to such fanatic loyalty. Ain’t nuthin’ better ‘n my 375 H&H. From rodents to rhinos, TOAST!

Combative North American hunters wanting to play the “you-don’t-know-jack-$#!+-cause-my-caliber-is-way-better-than-yours” game would likely make snarky, officious comments about my 375 H&H, such as: “Needlessly powerful”; “Way too much gun”; “Too much recoil”; and “Ya can’t get deader than dead”. My initial “back at ya” response would be: “So, you wouldn’t take a 12-gauge pump shot gun loaded with 00 buckshot to a knife fight because it wasn’t sporting?” My sequential responses to the comments would also be in the form of questions: “What do you mean by power and how much power is too much?”; “If a 375 H&H is too much gun, how much gun is just enough for a particular animal?”; “When will you grow a pair?”; and “What if you wanted to consistently stop an animal instead of just kill it?”

The intent of articulating this fictitious exchange is to identify typical issues that can mask a rational evaluation of a hunting cartridge selection, such as what chambering is “enough” to quickly take a specific game animal without displacing dental work every time the trigger is pulled. Fear of ridicule is also embedded in the selection process, as there is an irrational stigma associated with using a chambering that is considered “unsporting” because it is judged to be “too big”.

The rational, scientific basis for selecting a hunting cartridge for any non-dangerous game animal in any habitat is that the volume of the wound cavity produced by the bullet should be appropriate for the animal’s size. A “big” animal logically requires any cartridge with its attendant bullet to produce a “big” wound cavity volume in vital organs that results in a reasonably short travel distance after the shot.

It’s that simple. Colonel Townsend Whelen stated about a century ago that the basis of a bullet’s lethality was the volume of the wound cavity it produced. Colonel Martin Fackler’s published research in the 1970’s using FBI ordinance gel verifying Colonel Whelen’s assessment.

Data in the 2023 hunt report confirmed that a bullet’s lethality is directly related to its measured wound cavity volume in the animal, as there is a linear decrease in the animal’s travel distance after the shot with an increase in the wound volume measured in common organs. Such a relationship is shown in Graph 1, where the measured volume of the wound cavity through both lungs and the heart is directly related to a sprinted travel distance that was measured with a laser range finder. Assuming a constant sprint speed, this graph indicates that a larger wound cavity volume results in a shorter time to death, as postulated by Colonel Whelen and validated by Colonel Fackler.

Both of these military experts ignored a bullet’s energy, retained weight, mushroom diameter, and ability to produce “shock” as contributing to its lethality. Articles on this website discuss specific reasons why, as confirmed by field and skinning-shed data obtained on the management hunt.

In an ideal world, simply using a standardized test to obtain wound volume data that could be directly correlated to field wounding would make cartridge selection essentially a no-brainer exercise. Identifying a bullet that produced the biggest wound cavity volume for the cartridge under consideration would be fundamental in selecting a preferred bullet.

However, there is no testing method accepted by hunters or manufacturers to determine the wound cavity volume produced by a bullet based on its impact velocity. Even if such a standardized test existed and wound cavity volume data were available, there would likely be no consensus of how much wound cavity volume is “enough” for a particular animal.

Question: So, without accepted test data available to assess a bullet’s likely field wound cavity volume and some consensus of how much wound cavity volume is “enough” for a particular animal, how can any hunter reasonably select a cartridge loaded with a bullet considered appropriate for any non-dangerous game animal? Answer: The same way I vetted the chambering and bullets for the 2023 zebra management hunt: using a personal empirical “formula” to identify an appropriate bullet weight based on the weight of the animal.

This article is the first of two that presents how such a cartridge selection can be made without any test data from specific cartridges or bullets. It describes the basis for the empirical link between a bullet’s weight and a reasonable weight of a non-dangerous animal that can be expeditiously dispatched.

A hunting cartridge with its attendant chambering (“caliber”) can simply be thought of as a bullet’s launching platform, and the cartridge’s bullet can be thought of as its ordinance. Sidewinder missiles can be launched from an F-16; Hellfire missiles can be launched from an AH-64 Apache helicopter; and cruise missiles can be launched from a B-52. Note that the Sidewinder missile is the smallest and fastest (1900 mph/3060 kph) with the least “oomph”, and it is launched from the fastest, supersonic aircraft. The heavier, far-more potent Hellfire (995 mph/1600 kph) can be launched from an aircraft that can literally stand still. The heaviest and slowest ordinance is the cruise missile (550 mph/885 kph), launched from an “old and slow”, 1950’s-vintage aircraft with jet engines that can’t even get it supersonic. 

Both the aircraft and the ordinance are mission-specific. No matter how fast the aircraft, a Sidewinder missile is incapable of taking out a multistory building or a reinforced bunker. Matching the ordinance with an aircraft for a mission-specific mission is necessary for achieving desired tactical success. Likewise, matching the bullet with an appropriate chambering for a hunt-specific mission is necessary for consistently achieving a recovered animal.

The analogy in play is that matching both the cartridge’s chambering and bullet to the animal being hunted is necessary to achieve the desired performance-specific success. Although bullets cannot explode as can missiles, they do have weight. Bullets with greater weight typically have more momentum that can translate into the greater penetration logically needed for breaching the wider boiler-room of a larger, heavier animal. Bullets with more weight can also be ones with a greater diameter, simplistically representing a larger end area for potentially creating a greater wound volume. Bullets with greater weight also have a larger potential shrapnel reservoir for producing enhanced wounding, as discussed in a previous article. Bullets with greater weight may require an increase in caliber (diameter), with a correspondingly bigger chambering required to launch them.

In the aircraft-missile analogy, the aircraft and missile are matched to take out a target with known or assumed characteristics, one of which is simply size. In the context of an animal, “size” can be reasonably quantified by its weight. Just as a bigger missile with more explosives is required for a bigger target, a progressively bigger bullet with more weight can be considered reasonably necessary for taking out a progressively bigger animal. Consequently, a 55-grain bullet of any caliber (diameter) launched from any chambering is not a reasonable choice for a 1000-pound (400 kg) bull elk or a 700-pound (318 kg) zebra. Likewise, a 22-250 Remington chambering would not be considered reasonable for hunting either of these two animals, even though it can launch a 55-grain bullet at about 3800 fps (1160 mps).

The previous analogy can be simplistically synthesized down to a simple concept: the weight of the bullet required to reasonably take any non-dangerous game animal should be compatible with the weight of the animal. Achieving this bullet-weight-to-animal-weight compatibility allows consideration of both appropriate chamberings and bullet diameters (calibers) that are reasonable for the animal being hunted. 

“Reasonable”, in terms of a hunting cartridge with its bullet weight, has been identified for various animal species in books published by knowledgeable and experienced practitioners such as Kevin Robertson in The Perfect Shot (second edition), Craig Boddington in The Perfect Shot North America, and Finn Aagaard in Aagaard’s African Adventures. All authors have literally decades of hunting experience, allowing them to observe in actual field conditions what cartridges with attendant bullets work effectively on specific animals (and which ones don’t).

What if there was a simple, empirical way to reasonably/consistently relate cartridges with attendant bullet weights recommended/used by these experienced hunters to the weight of any non-dangerous game animal? Such a relationship would allow selecting a cartridge simply based on the expected weight of the animal, easily obtained online. If the chambering is known, as in the case of a hunter owning only one rifle, the relationship would allow selecting the cartridge’s bullet weight compatible with the intended animal’s weight.

For example, if a hunter only owned a rifle chambered in 7 mm Remington mag, would a 154-grain bullet be a reasonable choice to hunt a 600-pound Roosevelt elk cow, or would a heavier, 175-grain bullet be better? If the animal was a 700-pound zebra and a 30-06 was the only chambering available, would a 165-grain bullet be a reasonable choice, or would a 180-grain bullet be better? What about a BC-challenged, “slow-freighter-to-China” 220-grainer?

A simple, empirical formula that provides a reasonable way to answer these questions is presented in a subsequent article found here.