Bad things happen, and so does good things, and we are not always in control of the outcome. This topic is related to firearms — rifles in particular — in hunting contexts. P3 will be devoted to the only relatively small part that determines the final outcome, the BULLET. Related topics involving the bullet have to do with: construction, velocity at impact, accuracy and the animal itself. What do I look for and consider as a potentially effective bullet for medium, big, large or dangerous game? I’ll present a list of issues that I consider essential if I need to choose one among several. I’ll make some comments regarding each even though some matters may seem more important than others:
1 – Reports, not hype.
2 – Effective velocity parameters on game.
3 – Sectional Density (SD).
4 – Ballistic Coefficient (BC).
5 – Momentum and kinetic energy at impact.
6 – Construction.
7 – Potential weight retention in %.
8 – Accuracy.
9 – Useful to what range depending on muzzle velocity.
10-Flat tip (FT or FP) vs SP.
11-Fit for what class or classes of game. I go with a load for the potentially largest/most dangerous game I may encounter in a given area.
REPORTS: Those may come from friends or professionals, or both, but sometimes separating the “wheat from the chaff” is a matter of whom to believe as well as sorting out any contradictions. We need to ask a lot of questions, too many to go into here but a clear picture of what happened must be understood. For an example: When someone (friend or pro) says they’ve killed x-number of elk with a particular bullet, we need to know the cartridge, MV and ranges as a bare minimum, as well as approximate age and weight. And did they have to shoot the animal more than once?
EFFECTIVE VELOCITY PARAMETERS ON GAME: Most bullet companies don’t provide this, so it’s a guessing game until we find out for ourselves. Others make recommendations such as Woodleigh and Swift. Hornady makes recommendations for starting MV but NOT for terminal if the bullet in question is an expanding bullet and not a “solid”. We may have to ask questions, but even then the tech person on the phone may give the company promotional answer not based on the live testing of animals under varied physical conditions. Or he may be simply guessing.
This current series is in response to a bullet failure I experienced on a big 400 lb whitetail buck. Most companies have solved the over-expansion or breakup of soft-nosed bullets by making them monometal with poly tips in a hollow cavity or with bonded cores. But the issue of NO expansion has become a more recent problem when the impact velocity is below a certain point, or the impact area of the game is too soft to provide suitable resistance for the needed expansion — resulting in what is known as a “pencil” effect with the barest of tissue destruction. The bullet may fully penetrate but with minimal effect. I’ve previously written on this in regard to a 350gr Barnes TSX NOT expanding on a medium bear from my CZ550 in .458 Win Mag leaving the muzzle at 2750 fps and impacting at over 2400 fps. That bear went the farthest of any I’ve shot with a .458-caliber bullet. Most have been “bang-flops”!
SECTIONAL DENSITY (SD): This is the RATIO of the bullet’s weight to its diameter or caliber. The heavier a bullet is in relation to its caliber, the longer it will be. All reloading manuals include the SDs of their respective bullets — and for good reason. All other matters equal, a higher SD generally means better penetration. Penetration, however, is also contingent on bullet construction and bullet impact speed. Heavier bullets for a particular caliber from the same company also tend to have somewhat thicker jackets in the case of alloy jackets with lead cores. A partition within the jacket plus bonding lead to the jacket, and their hardness, also affect weight retention and penetration. So, penetration is the result of several factors of which SD is an important item. I’ve written much more extensively on this matter in former blogs.
BALLISTIC COEFFICIENT: This also is given for individual bullets in handloading manuals. There was a time when bullet manufacturers were perhaps too optimistic in this regard. It was a calculated number that basically described the efficiency of a given bullet in overcoming the drag resistance of the atmosphere it passed through. The higher the number the more efficient the bullet was in maintaining its velocity to target. That was largely based on the bullet’s profile/shape in relation to its weight and caliber. The “pointier” it was the better it was in defeating air resistance. A round-nose or flat tip was therefore less efficient (slowed more rapidly) and became less desirable in the minds of the average buyer. Of course rifles with tubular magazines had to use blunt-tipped bullets that made the rifles with lever-actions and tubular magazines somewhat a “relic of the past”. Therefore, bolt-action magazine rifles have won the battle for ballistic efficiency and long-range shooting despite the fact that most game are taken at ranges where bullet efficiency makes little difference. In fact, there is an advantage to heavy-for-caliber RN and FT bullets at closer ranges that produce more immediate “shock” and a larger permanent wound cavity than some others designed for expansion at long range which tend to “blow up” more quickly at close range and higher velocities.
<These are 465gr/.458″ semi-hard cast with a 1/4″ meplat. One was devastating on a good black bear from a frontal hit at 70 yards. They were leaving the muzzle of my single-shot NEF .45-70 at 1900 fps. It was a DRT and the bullet was never found. They were shooting MOA in practice.
There are, of course, bullets like the “premiums” and “super-premiums” that work quite well at both relatively close and far distances. However, there is far too much that could be said to detail the pros and cons of each in a few sentences or even chapters in a book. In an 1895 Marlin lever-action in .45-70, heavy flat-point bullets, both cast and factory, work well beyond their calculated kinetic energy numbers. That’s due to momentum, bullet diameter and shape, SD and the “hammer effect”. Same could be said of any large bore shooting heavy bullets with wide-flat tips. The theory can be understood but the practice is conclusive to those who have experienced it… and I’m one of “those”!
MOMENTUM and KINETIC ENERGY at IMPACT: Like all serious students of firearm ballistics, I too have spent endless hours pondering, studying and researching both scientific theory AND practice related to both issues. Neither of which standing alone seems to satisfy or answer all issues and questions related to TERMINAL EFFECT. It would seem, therefore, apart from bullet structure, that some integration or combination of the two is the best approach. But the challenge of that is: How to do it?
Some have attempted to use empirical evidence based on some combination of bullet construction, nose profile, impact velocity and type of media, such as body part or bone impacted. In my mind there are far too many variables in that approach to come up with a general consensus.
Others have decided on momentum alone, such as the KO and TKO formulas.
Still others hang with the kinetic energy number alone.
As in the late John Wootters case, I’ve tried to integrate KE at impact with SD and CSA (cross-section area before expansion rather than mere caliber which John used), and that’s not totally satisfactory either as the end result is momentum at impact of one bullet vs another. However, if a KE number is selected on its own, in isolation from the rest of the formula, then modified by SD and CSA, it works better.
For example: choose 2000 ft-lbs standing alone at impact from ANY bullet and caliber, then modify THAT (2000 ft-lbs) by SD and CSA and we see differences in final results that may be expressed as Terminal Effect or simply TE as a comparative thing. Incidentally, my formula preceded Wootters’ Lethality Index by about a year.
< That’s a 450gr Swift A-Frame on left and a 500gr Hornady RNSP on right, both loaded to standard .458 Win Mag COL of 3.34″.
As an example, let’s stick with 2000 ft-lbs, first from a 500gr/.458, then from a 350gr/.458, and finally from a 150gr from a .30-06:
2000 x .341 x .165 = 112.53 TE
2000 x .238 x .165 = 78.54 TE
2000 x .226 x .074 = 33.45 TE
Then, of course, using ballistic charts we can determine at what ranges those bullets produce 2000 ft-lbs depending on MV and BC.
It’s a comparative thing in which I use 50 TE, as an example, for a bull moose of 1000 to 1200 lbs. Larger numbers and smaller can be extrapolated from that.
It works for me as a “rule of thumb”.
Let’s do an analysis of some of that: Notice the difference in results between the 500gr and the 350gr, both .458-caliber, but producing 2000 ft-lbs at impact, however at distinct ranges. The difference in results suggests why a 500gr would be far superior on large game than the 350gr though each is producing identical energy at impact. The distinction is found in their relative SD’s. There’d be little doubt in the minds of the cognoscenti which would penetrate better on large animals assuming the same construction. For one important matter the 500gr is producing 19.5% more momentum and, secondly, it’s SD is 43% greater!
So while KE has a voice in the demise of a large beast, it isn’t a solo act!
The 2000 ft-lb result from the .30-06, 150gr would suggest a need for a heavier bullet producing the same 2000 ft-lbs. If we exchange the 150gr for a 200gr making 2000 ft-lbs at impact, we have a legit 1000 to 1100 lb moose killer. It will make that KE number at close to 400 yards (much farther than the 150gr) while producing a greater TE. That we already know intuitively but it’s nice to know it empirically as well.
Coming up in P4 will be the final six points and a wrap-up of how I select bullets for particular rifles and game… hopefully avoiding a “worst case scenario” due to bullet failure!