23 October 2017


26 JANUARY 1997

Prepared for Wyoming Game & Fish Dept.
by Cope Reynolds
Cody School of Practical Shooting
POB 914
CODY WY 82414

Bullet Performance on Big Game

I wrote the following piece back in 1997 and submitted it to both the Wyoming Game & Fish Department and the Wyoming legislature in an effort to interject some common sense into the hunting regulations which I supposed at the time were written by people that had neither shot nor hunted much. My biggest gripe was allowing the .243 for elk, moose, etc. along with a couple of other issues. Before you get the pitchforks and torches out, please read the article...


The purpose of this report is to provide information concerning the minimum caliber restrictions for elk and moose. I do not claim to be an expert, however I am a lifelong hunter, handloader, competitive shooter and professional firearms instructor. Being a hunter does not keep me from being sympathetic towards any animal that is not harvested cleanly and swiftly.

I would like to see the caliber restrictions raised to a larger caliber in an effort to reduce the chance that animals will be left to die from infection, predators or the elements. I feel that the current restrictions were created more from biased opinion and/or public pressure than from the actual study of terminal ballistics, both in the field and from the numerous manuals and reports that are available to the public.

This is not to say that, in the hands of a responsible sportsman and expert rifleman, the .243 Winchester will not cleanly take an elk. But, if you consider misjudgement of distance, wind speed, nervousness, fatigue, overconfidence, inexperience, failing light conditions or bad shot placement you will almost certainly have a wounded animal to try and recover. I also understand that we will lose some animals no matter what we use, but by using a larger caliber and prohibiting some types of bullets, we can help compensate for those factors that prevent perfect shot placement.

In the following text, I will present a number of facts that should help to explain why we should increase the minimum caliber allowed for elk and moose.

Energy vs. Momentum

Webster describes momentum as “the product of a body’s mass and linear velocity.” Mass of a body is best described as the physical volume or bulk of a solid object.

I’m not trying to turn this into a physics class, but the figures that one derives from various ballistics tables and product advertising are expressed in foot pounds of energy and do not take into account the bullet’s diameter. Diameter must be included to determine mass. These figures are very misleading and mean nothing when comparing bullets of different calibers.

In an extreme example, a 180 grain, .30 caliber bullet fired at 2700 feet per second (fps) will generate 2913 ft. lbs. of energy (fpe). In contrast, a 5 grain, .177 caliber BB fired at 16,250 fps will generate 2932 fpe. Does this mean that the BB is equally suited to big game hunting as the .30-06? I think not. While both show the same theoretical energy in the printed ballistics tables, they will not deliver the same energy to the target.

By factoring in the diameter of the bullet, you have realistic means with which to compare the striking force of any projectile at any speed or distance. This formula is commonly referred to as the “Taylor Factor” or the Taylor Knockout Factor”. TKO for short. By applying this formula in cartridge comparisons you will come to understand why the venerable .30-30 still accounts for more than it’s fair share of big game every year even with its modest, advertised 1762 ft. lbs of “energy”.

Neither of these formulas takes into account the performance of the bullet which, along with proper shot placement, is ultimately the deciding factor in bringing home the bacon (or venison). However, the Taylor Factor will give you a way to compare the force applied at impact which is directly proportional to the bullet’s ability to smash bone and penetrate heavy muscle. The .243 class of cartridges generally lacks the momentum and proper bullet construction to reliably penetrate the shoulder bone, that often covers the vitals and still reach the vitals intact.

Bullet Performance

The variables in this topic are virtually endless so I will try to sum it up in a reasonable amount of time.

There is a happy medium somewhere between full metal jacketed, non-expanding bullets that cause almost no tissue damage or trauma and the hollow point bullet that may expand too rapidly and cause shallow but grievous flesh wounds that may cause an animal to die a slow, lingering death. Remember that we are talking about big game here, not rabbits and coyotes.

There are no jacketed hollow point rifle bullets, to my knowledge, that are expressly made for big game. The exception to this are the homogeneously made bullets such as the Barnes-X bullet which is an outstanding performer on almost any size game. These bullets are not jacketed but are constructed throughout of the same material, therefore usually providing perfectly controlled expansion and a devastating wound channel. The overwhelming majority of hollow points (for rifles) are made either for varmint hunting or target shooting and will reliably offer the penetration and proper expansion needed for a humane kill on big game. They either expand too violently allowing little penetration or, in the case of match-grade hollowpoints, due to a manufacturing process that leaves a very small opening, may collapse inward causing the bullet to perform more like a full metal jacketed bullet. Neither of which is conducive to quick, clean kills.

My idea for the restriction of hollow point rifle bullets stems from the fact that I know at least 3 people that regularly hunt elk with them, with varying degrees of success. I know one man that hunted elk last year with a .243 Win. using 75 grain hollow points. I was appalled that anyone would use a varmint bullet on any big game much less an elk or a moose. It’s a shame that we have to place legal restrictions on something that should be regulated by common sense and respect for our quarry. Luckily, this hunter was successful but the elk was no more than a calf. The same hunter wounded a large cow on the previous weekend that my wife finished off with a .30-06.

Handgun Bullets

This hollow point data does not necessarily apply to traditional, straight-walled handgun cartridges or such rifle cartridges as the .45-70 and .444 Marlin. These are hollow soft points that are designed to expand controllably at lower velocities and penetrate as well. They do not exhibit the violence of the higher velocity rifle bullets. The regulations specify soft or expanding point bullets. This is logical for high velocity rifle bullets but, by the letter of the law, restricts a couple of the most effective handgun bullets made, the hard cast flat nose and semi-wadcutter. These bullets, unlike roundnose bullets, remove tissue to its full diameter which causes free bleeding entrance and exit wounds and allows air to get to the heart very rapidly. Organ and tissue damage is guaranteed and penetration is usually complete. The probability of one shot kills with these bullets is very high if properly placed.


This report is more than one man’s opinion. I have done a considerable amount of research on the subject to be certain that I was armed with enough evidence to make a case. In light of these facts, coupled with the experience of myself and others, I would very much like to see the minimum rifle caliber raised to at least .25 and preferably .27 for elk and moose and the banning of jacketed hollow points that are not designed specifically for big game hunting.

In the accompanying table please note the degree of contrast between Energy and Striking Force (TKO) in any given caliber, then see the difference in the TKO between some of the most popular big game calibers.

According to the Energy table, the .223 Rem. would be better suited for big game than the .44 Magnum. However, the .44 equals the .30-06 at the muzzle in the TKO table. You will find that the .30-30 and the .257 Roberts both have more striking force at 300 yards than either of the .243 bullets. Even the .357 Magnum rivals the .243 at 100 yards and the .357 is illegal!

You have rightfully specified expanding bullets but I ask you to please consider these recommendations for the same reasons.

In the vast expanses of Wyoming in which we hunt, many hunters are overcome with the temptation to shoot at distances that are totally unreasonable for any caliber. The .243, being touted as a flat shooting, long range rifle, is relatively easy to hit with at these ranges and is therefore expected (by some people) to do the same things that the “big” guns do. The same person, shooting a .30-30 or .44 Magnum, would probably not be tempted to make the same shot.

You can call it stopping power, knockdown power, energy, momentum, striking force or whatever you want, but the .243 caliber in any cartridge, absolutely does not have enough of it to be reliable on animals the size of a horse!

If you wish to figure some other cartridges, here are both formulas:
Foot Pounds of Energy:

Velocity (in FPS) squared x weight (in grains)÷ 450,400 = ft. lbs.

The Taylor Factor:

Velocity x Caliber (in inches)x weight ÷ 7000=Taylor Knockout Factor (TKO)


CRTG/WEIGHT VELOCITY              ENERGY/ FTLBS                     TAYLOR FACTOR  
                                    MUZZLE  100 yds.   300 yds.          MUZZLE  100 yds.  300 yds.

.223 Rem/55Gr  3200 FPS   1330        1011        558                 5.6        4.9          3.6

.243 Win/75      3300 FPS   1813       1458         918                 8.6        7.7          5.6

.243 Win/100    2900 FPS    1867       1584       1083                10.1        9.2          7.7

.257 RBTS/75    3300 FPS    1813       1412        826                 9.1         8.0          6.1

.257 RBTS/100   3000 FPS    1998       1662       1124                11.0      10.0          8.3

.257 RBTS/120   2800 FPS    2089       1760       1225                12.3       13.3         9.4

.270 WIN/100    3400 FPS     2566        2086       1349               13.4       12.1         9.8

.270 WIN/150    2800 FPS     2611        2257       1663               16.6       15.5        13.3

.30-30 WIN/150  2300 FPS    1762       1175          501               15.2       12.4         8.1

.30-06/165        2900 FPS     3081       2594        1803               21.0       19.3        16.1

.338 WM/225     2800 FPS     3916       3304        2307                30.4       28.0        23.3

.45-70/300        1600 FPS     1705       1134         638                31.4        25.6        19.2


  CRTG/WEIGHT     VELOCITY               ENERGY/ FTLBS                       TAYLOR FACTOR          
                                           MUZZLE    100 yds.   300 yds.        MUZZLE   100 yds.  300 yds.

7MM TCU/120      2300 FPS        1409        1141        728               11.2         9.1         8.1

.44 MAG/265       1300 FPS        1126          801        534               21.1        17.8       14.5

.357 MAG/158     1400 FPS          593          412        N/A               10.5          8.7        N/A

In Liberty, Cope Reynolds (Desertscout)
Southwest Shooting Authority of Arizona

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