Point Blank Range
The game at which the weapon is to be used naturally has a bearing on the permissible trajectory height. For deer that are usually shot at distances under two hundred yards, and being small require close holding to reach a vital spot, it would not be wise to tolerate a mid-range error of five inches, the chances being that most of our shots would be taken at just the distance where the bullet was farthest from the line of sight, one hundred to one hundred fifty yards.
However, if the game were of a large variety like elk, moose, or the larger African antelope, the three thousand foot velocity rifle with a trajectory of five inches at three hundred yards might well be sighted for that distance, and no especial difficulty should be had in holding a trifle low for the mid-ranges. For a deer rifle I should be inclined to place the highest practical trajectory height at four inches. This can be secured from a Ross or 7 mm. Mauser-Spitzer, at 250 yards, from the .30-30 at 165.
With the old-time black powder rifles the size of bull’s-eye in which the bullet must strike anywhere along its curve of flight was given at eight inches. It might strike the top of the eight-inch bull at one hundred yards and the bottom at two hundred, and the latter distance was supposed to be within the point-blank range of the rifle for big game shooting. However, with modern, high-power arms I should take the size of the bull at six inches, which circle the bullet must not leave up to the maximum distance.
If the rifle is to be sighted for the center of the bull at two hundred yards it is evident that the trajectory must be less than three inches high midway in order to keep within the bull. Such trajectory can be secured from a rifle having a muzzle velocity of 2,600 to 2,700 feet. A rifle with a lower velocity will still keep within the bull by sighting it to strike at six o'clock at two hundred yards in place of in the center.
The difference between the two guns is that the higher velocity will keep within the bull for some distance beyond the stipulated range while the other will not. Thus we can see how flat trajectory very kindly makes amends for bad judgment of distances.
To come down to brass tacks, other things being equal, the trajectory of a big game rifle cannot be too flat. If it has but a one-inch trajectory at two hundred yards that is admirable. Furthermore a six-inch two hundred yard trajectory is the very highest permissible in a high-power rifle for any game. Increasing the muzzle velocity from 2,000 to 3,000 feet lengthens the distance at which the rifle will land in the circle nearly one hundred yards. All this is considered as other things being equal, remember.
In black powder days, sacrifices of accuracy, power, and range were made in order to secure flat trajectory. The old principle of sacrificing one essential to secure another still more important might still hold. Let us see. Suppose that in securing our three-inch trajectory at two hundred yards we had to sacrifice accuracy to such an extent that a circle of ten inches would be required to contain a pattern of shots. It is quite evident then that our flat flight would be useless since we could not keep within the given circle in any event. We may, therefore, take it as a simple statement of fact that trajectory and accuracy must be equal.
A three-inch trajectory with a ten-inch accuracy pattern is no better than a ten-inch trajectory with a three-inch pattern. But if we can combine a three or four-inch trajectory with a four-inch pattern, we have a great shooting gun—a great shooting gun that might still possibly lack power. I say might lack power because a flat trajectory implies power of itself if the bullet is of decent weight and right shape.
It is claimed for the military cartridges, like the '06 Springfield, .280 Ross, 7 mm. Mauser, .2550 Newton, that they combine in the greatest degree flat trajectory, accuracy, and power. If this is so, and there is not any question at all except as to the power with full mantled Spitzer bullet, they are a wonderful advance in cartridge making.
Askins, Charles. Rifles and Rifle Shooting. New York: Outing, 1912. Print.
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