Reasonable Caliber and Cartridge Guidelines for Hunting Big Game

By Chuck Hawks

This is simply a guide to choosing at least a minimally appropriate rifle caliber/cartridge for hunting the three classes of big game animals known as CXP2, CXP3 and CXP4. CXP2 refers to all thin-skinned, hoofed game averaging under about 350 pounds in live weight. In North America, this includes all deer species, pronghorn, sheep, goats, caribou, black bear and average size feral hogs. It would also include most deer, antelope, sheep, goats and similar size animals around the world.

CXP3 refers to large thin-skinned non-dangerous game and the smaller dangerous predators. The former would include North American elk, moose and musk ox, Scandinavian moose, European red stag, African kudu, Oryx, eland and similar size game animals around the world. The latter are primarily the smaller "big cats," such as leopard and jaguar. Large black bear and European wild boar might also be included. Remember the old adage: "When in doubt, use enough gun."

CXP4 represents very large, thick-skinned, dangerous game and the largest predators. Examples of the former include American bison, Asian water buffalo, African Cape buffalo, rhino, hippo and elephant. The latter include North American grizzly and brown bear, Arctic polar bear, African lion and Asian tiger. The big predators can reasonably be hunted with powerful medium bore rifles on the order of the .338 Win. Mag. and .350 Rem. Mag. where legal, but the use of big bores along the lines of the .458 Win. Mag. is also common. In most African countries, calibers of at least 9.3mm or .375 are mandated by law for all CXP4 game, including lion.

Caliber (bullet diameter) is not an accurate indication of killing power, so alone it is not a reliable guide to cartridge selection. For example, the .375 Winchester is primarily a deer and black bear cartridge, while the .375 H&H is an international dangerous game cartridge. Similarly, the .44-40 and .44 Remington Magnum are technically big bore cartridges, but they are CXP2 game calibers in terms of killing power. The ancient .45-70 is a true big bore caliber and with heavy bullets it is suitable for CXP3 class game, but it is not recommended for hunting CXP4 game.

I suggest using Hornady's HITS (Hornady Index of Terminal Standards), as well as bullet diameter (caliber), as a guide to choosing acceptable cartridges for hunting the three classes of big game animals. Although no system of estimating killing power is perfect, Hornady's system includes such factors as bullet weight, sectional density, ballistic coefficient and impact velocity at 100 yards to derive HITS ratings to estimate and compare the killing power of rifle cartridges and loads at 100 yards. Naturally, these HITS ratings are based on the use of modern, controlled expansion bullets suitable for the game in question. Varmint bullets, match bullets and military type full metal jacketed bullets are not big game hunting bullets and should never be used as such. There is an extensive list of HITS ratings for hunting cartridges on the Tables, Charts and Lists page and Hornady has a free HITS calculator on their web site that you can use to find the HITS rating of any load you wish.

I hope that the simple guidelines that follow are useful to hunters. I wish that all game departments would adopt similar rules, instead of relying on caliber alone to establish the legality of big game hunting cartridges.

  • Requirements for hunting CXP2 game: Minimum caliber, 6mm (.243"); HITS rating, 500-900
  • Requirements for hunting CXP3 game: Minimum caliber, 6.5mm (.264"); HITS rating, 901-1500
  • Requirements for hunting CXP4 game: Minimum caliber, 9.3mm (.366")*; HITS rating, over 1500

    * Minimum mandated by law in many African countries.

Let's look at a few common rifle cartridges to see how they score in terms of their 100 yard HITS rating. For CXP2 game, two popular deer cartridges and loads are the .243 Winchester shooting a 95 grain bullet at a muzzle velocity (MV) of 2950 fps and the .30-30 Winchester using a 150 grain bullet at 2390 fps. The HITS ratings for those two cartridges are 587 and 664 respectively, indicating that they are adequate deer and antelope cartridges, which is confirmed by long experience in the field. Compare those numbers to the 283 HITS rating of the .223 Remington shooting a 60 grain bullet at a MV of 3115 fps, or the .220 Swift shooting a 60 grain bullet at a MV of 3600 fps for a HITS rating of 328 and you can see why even the most potent sub-.24 caliber cartridges should never be used to hunt big game.

Moving to CXP3 game, the extremely popular .30-06 with a 180 grain bullet at a MV of 2700 fps scores 1215 HITS and the hot Hornady .45-70 factory load using the 325 grain FTX bullet at 2050 fps scores a similar 1242 HITS. These numbers are well above the 901 HITS lower limit for this class of game and both of these are proven elk and general CXP3 game calibers. Conversely, the .25-06/117 grain bullet at 2990 fps scores only 814 HITS indicating that, although it is an excellent deer cartridge, it would be a poor choice for hunting CXP3 game.

For hunting heavy CXP4 game, the 9.3x62mm is about the minimum recommended cartridge. Shooting a 286 grain bullet at 2360 fps, it scores 1863 HITS, comfortably above the required 100 yard HITS rating of 1501. The elephant busting .458 Winchester Magnum, launching a 500 grain bullet at a MV of 2140 fps, has a prodigious HITS rating of 3205! As we have already seen, the .45-70 (ditto the .450 Marlin), while they shoot the same diameter bullets as the .458 Magnum, fall far short of its power.

The bottom line is that these caliber and HITS ratings conform well to what we have learned in the field after over 100 years of hunting big game with centerfire rifle cartridges. They should serve as a simple and reasonable guide to selecting calibers and loads for big game hunting.

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Copyright 2010, 2016 by Chuck Hawks. All rights reserved.