One method for estimating stopping power is the "Optimal Game Weight" method. BigGameInfo.com has a page containing an extract from the Lyman #47 Manual discussing Optimal Game Weight and a table of typical weights of large game. Since an adult coyote weighs as much as 45 lb (more than ten times the weight of a squirrel), their expression tells us:
• The 32 gr Remington Accutip needs more than 3100 ft/sec -- Limits .204 Ruger to 200 yards when using this bullet.
• The 55 gr .223 bullet needs about 2150 ft/sec, keeping the range to under about 250 yards for most bullets
• Surprisingly, 150 gr 30-30 bullets need about 1100 ft/sec, giving it a lethal range of almost 400 yards.
The Optimal Game Weight method tells us that the bullet would likely do the job with a good hit even out to 400 yards. So, how likely are we to get a good hit as the range grows long?
Trajectory -- Within what folks describe as the "point blank" range the flight of the bullet stays within the vital zone, subject to accuracy limitations. Outside this range, adjustments to windage and elevation need to be applied to get the bullet into the vital zone.
Furthermore, adjusting the zero to correct for range and current wind conditions is very difficult with most scopes used for 30-30 rifles. This means that Tennessee Elevation and Kentucky Windage both need to be used to get the bullet into the right part of the target at the longer ranges.
Figure 4. Looking through the crosshair, we see that a 10 mph wind from the left causes the 150 gr 30-30 bullet to drift right with increasing distance. The ellipse indicates error caused by misjudging wind speed by only 2 mph!
Figure 4 above shows us that both the drift from a 10 mph wind and the drop at 300 and 400 meters make a precise shot very challenging. Furthermore, the uncertainty in wind drift means that we'll have better than a 50-50 chance of only wounding the animal or missing it completely even when the offset and holdover are nominally correct. Hence the shot is questionable even though the bullet would be effective given a solid hit.
Figure 5. Sight picture needed to get center of impact on coyote vital zone at 300 and 400 yards when sighted-in on the mark at 100 yards. The red ellipse indicates where about half of the shots will hit with a 10 mph wind from the left and a wind-estimation error of 2 mph. (Photo credit: US Fish and Wildlife Service)
Returning to our original question about the 200 yard shot, we see in Figure 6 below, that we likely could have taken the shot ethically even with a 10 mph wind. To be sure, we would want to offset our aim to account for wind drift and bullet drop, but we should be able to take a clean shot.
Figure 6. Sight picture needed to get center of impact on coyote vital zone at 300 and 400 yards. The red ellipse indicates where about half of the shots will hit with a 10 mph wind from the left and a wind-estimation error of 2 mph. (Photo credit: US Fish and Wildlife Service)
Many, if not most, scopes on 30-30 rifles today have duplex reticles. Among other things, these reticles help with range estimation. Note in Figure 6 that at 200 yards, the length of the coyote's body is about the same as the distance between the center post and the beginning of the thick section of the crosshair. We can see that when the coyote is smaller than this, the distance is greater than 200 yards, and that we are not likely to be sure of an ethical shot.
Not all scopes are duplex and of precisely the same as that illustrated here, so you will need to check the references for your scope. Practicing on small paper plates at appropriate distances will help develop your competence and improve your confidence. You'll probably have some fun too!
Last, we ask, "How would these conclusions change if I went to, say, a bullet like the new 140 gr Hornady Monoflex load for the 30-30?" As above, the plu or minus 2mph limitation in our assumed ability to judge and correct for wind drift controls the maximum ethical range. The 2500 ft/sec muzzle velocity and better ballistic coefficient, however, extends this limitation out to about 300 yards.
Not bad for an old “backwoods” deer rifle!
Joe Smith is an avid shooter and reloader who has competed in the NRA 2700 matches (.22, .38, & .45 bullseye shooting) as well as international style air pistol. He has instructed rifle and shotgun skills for Boy Scouts of America shooting sports. He recently retired from the University of California after more than thirty years dedicated to research and development of a wide variety of weapons. He is a Vietnam Veteran and an NRA Life Member.
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