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CHAPTER IX.

The Danger Zone.

Problem 14A.

HUNTER estimates the distance of an antelope to be 500 yards and sets his sight accordingly to hold on the middle horizontal line of the animal. What error may be made in estimating the distance and still hit the antelope, assuming the vertical vital zone to be 12 inches in width?

M

Fig. 8

Assume the antelope to be at O, Fig. 8, 500 yards from M, and O on the middle horizontal line of the animal. If the height of the ordinates y' and y" is 6 inches, it is evident that the antelope must not be nearer than y' or the hunter will overshoot, nor beyond y" or he will undershoot.

1

t' =

(T + √(T2 - h -) ›

2

For. 25

in which t' is the time of flight to the foot of the ordinate y' whose length is 6 inches or 0.5 ft., h=y'=y"=0.5 ft. and T the time of flight for 500 yards.

Using for illustration

the value of T for the

Springfield, .30-150-2700-.389 which is 0.709 sec.,

.5

(0.709 + √(.7092 — 5) ) =.662 sec.

4

1

2

in which v' is the velocity at the ordinate y', or any

in which DX is the distance, in feet, from to the foot of the ordinate y', and v the velocity of the projectile at o, or 500 yards.

That is if he OVER estimates the distance 29 yards, he scores a miss, by shooting over.

Again, let t" be the time of flight to the negative ordinate y", whose length is 6 inches or 0.5 feet.

1

or v = (T+ + √((H+y))

2

or

t' =

1

4

-)

For. 28a

) .752 sec.

(.709+√(2.035 +0.5)) = .752 sec.

t(v")=1+T(V) by formula 26.

DX=C{S(v")

S(v")

S(1630) =

S(v) by formula 27.
= 6672.7

S(v) = S(1668) = 6497.5

multiplied by C

DX

175.2

.389

68.15 ft. 22.7 yds.

That is if he UNDER estimates the distance 22.7 yards he scores a miss by shooting under. He must, therefore, make his estimate within a total distance of 51.9 yards.

The danger zone is that zone or zones over which the projectile in its flight is neither above nor below the limits of the vital zone of the animal aimed at.

The danger zones of the antelope, Problem 14A, extends from M to y, and from y' to y". The ordinates y,y' and y" are each six inches in length; hence

the projectile is neither above nor below that distance as it passes across these zones.

If the vital zone of the animal at O be equal to the ordinate y'", then the danger zone of the larger animal would extend from M to y'". In the first case the danger zone of the antelope is discontinuous, in the second case the danger zone of the animal is continuous.

For hunting purposes the danger zone of the animal hunted should be continuous. It is clear then, that the range MO must be less than 500 yds. if the danger zone of the antelope shall extend from M to O.

The point blank range, so called, because the bullet was formerly supposed to travel in a straight line for a short distance, is a misnomer.

Technically speaking, it implies a condition that cannot exist; but since the term is in common usage, we shall continue its use, but with the restrictions in the definition as given.

The point blank range is that range within which the projectile does not rise above or fall below the object aimed at. Inasmuch as the danger zone of a given projectile is determined by the size of the vital zone, the point blank range of that projectile is that space within which the projectile must not rise above or fall below its limitations.

That hunter who is able to set his sights to obtain the maximum point blank range within the limits of the game hunted will score the greatest number of hits, other conditions being equal.

Problem 14B.

Given, any projectile, say (.30-150-2700-C-.389) Width of vertical vital zone, say deer 8 inches. To determine the point blank range.

Allowing for the vertical deviation of the projectile and error in sight, the height, H, of the trajectory should not be greater than 1⁄2 (8-2) or 3 inches.

Solving

1st. By formula 5A, T=.25 sec.

2nd. By formula 26, v=2235 f.s.

3rd. By formula 24, X=612 ft.=204 yards. Hence, the rifle using the above projectile sighted for 200 yards will fulfill the requirements.

Again to determine the danger zone from M to y", Fig. 8, y" being beyond the 200 yard range. It is evident that the projectile must not fall below the line of sight over the limitations set by the target, in this case 3 inches.

4th. By formulae 28a, 26, 27 used in order named, oy"=DX=, say for illustration, 40 yards. Hence, the total danger zone for the projectile used in illustration with the sights of the rifle set for 200 yards is approximately 240 yards.

It is quite clear that a rifle having a point blank range for a large target is not practical for game considerably smaller, yet the reader must not infer that the hunter may not decapitate a squirrel or grouse using his rifle sighted for big game.