From "Chuckhawks"
Just passing this along.
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Killing power
Assuming a proper hit in the animal's vitals, killing power is determined by a complex of factors including (but not entirely limited to) the width and depth of the wound channel. This, in turn, is influenced by bullet energy, frontal area, sectional density, and expansion characteristics. In other words, it is a complicated matter that is still not entirely understood.
There have been many systems devised to compare the killing power of rifle cartridges, most of them by people with a pre-existing bias of one sort or another. The best and least biased of such systems of which I am aware is the Optimum Game Weight (OGW) formula devised by Edward A. Matunas and published in the Lyman 47th Reloading Handbook. Matunas tried to account for a variety of factors, not just caliber or kinetic energy or momentum, the major failing of most killing power formulas.
Like all such systems, OGW is not perfect. I find that it seems to be most reliable when dealing with mainstream centerfire rifle cartridges on the order of the .243 Winchester, .270 Winchester, .30-06, and .338 Win. Mag. Since we are dealing with much less powerful small bore cartridges in this comparison, I suggest that we view the following OGW information as a comparative tool, not as an absolute guide. That, in any case, is usually the best approach when dealing with killing power formulas.
The OGW figure estimates the optimum live weight of the animal for which the cartridge is best suited at any given range. Note that the OGW weight is not the biggest animal the cartridge will kill, merely the optimum size animal for that range. Also note that individual bullet performance is not a factor in calculating optimum game weight; it is assumed that the hunter will choose an appropriate bullet for the job at hand. And it is also assumed that the bullet will hit the heart/lung area of the animal; brain or spine shots would obviously result in much higher OGW numbers, but they are not considered. Here are our two best long range loads for OGW comparison:
.17 HMR, 17 grain = 7 pounds at muzzle, 5 pounds at 50 yards, 3 pounds at 100 yards, 2 pounds at 150 yards, 1 pound at 200 yards.
.22 WMR, 40 grain = 17 pounds at muzzle, 9 lbs. at 50 yards, 5 pounds at 100 yards, 3 pounds at 150 yards, 2 pounds at 200 yards.
The OGW figures indicate that the .22 WMR has superior potential killing power at all ranges. We could summarize by saying that the .22 WMR has about as much killing power at 100 yards as the .17 HMR does at 50 yards. Since its MPBR is limited to about 125 yards, the .22 WMR is probably the better choice for large varmints and small predators within the limit of its MPBR. Beyond the MPBR, accurate bullet placement becomes increasingly difficult as the range increases, and bullet placement is the most important factor in actual killing power.
One more thing Okrattler hit it on the head.
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I love my .17HMR but porcupines are about the biggest critter I would expect it to kill consistantly.
Constistantly means alot to me. I have killed a few yotes with a 22lr in my time out of opputunity, but I wouldn't go out to "hunt coyotes" with it or a 17hmr. Use the right tool for the job. Anthing less is not fair to you or the prey that you seek to harvest. IMHO The argument that a 17hmr is an appropriate tool to HUNT coyote with is laughable at best. /ubbthreads/images/graemlins/confused1.gif Would you hunt geese with 6 shot in 20GA? Same thing if ya ask me, nonsense.
