BM = Axis of barrel
MF = Line of departure
MS = Line of fire
LOS = Line of sight
MTS = Trajectory
Fig. 2. Illustration of Trajectory etc.
AG = Horizontal plane
CMF = Axis of barrel
BMO = Line of sight
ML = Line of departure
BMC = Angle of tangent elevation—T
OMP = Angle of sight—S
FMP = Angle of quadrant elevation—QE
LMP = Angle of departure—D
LMF = Angle of jump—J
MHO = Trajectory
Fig. 3. Illustration of Trajectory etc.
(ii) For under war conditions targets beyond close range are usually invisible or indistinct, and frequently in motion; distances are uncertain and difficult to judge; firing takes place under all conditions of light and atmosphere over every variety of ground, under the strain of excitement and fatigue in the face of artillery and rifle fire, with weapons which rapidly become imperfect owing to heavy wear. Accordingly, the theory of rifle fire is considered in this book in relation to practical service conditions.
3. Technical Terms.—The different technical terms used in this chapter in explaining the theory and application of rifle fire will be found among the Definitions (p. xxii). Some of these terms are illustrated in Figs. 2 and 3. In addition, the following technical terms may conveniently be quoted in this paragraph:
(i) Individual Fire.—Individual fire is fire opened by individual soldiers without orders from a fire-unit commander. When men fire individually, each one selects his target, estimates the range, and regulates his fire according to his own judgment.
(ii) Collective Fire.—Collective fire is the fire of a number of men combined for a definite purpose under the orders of a fire-unit commander, who indicates targets, gives ranges, and controls fire as to rate, etc.
Note.—Collective fire is necessarily controlled fire. Individual fire will also be controlled if circumstances permit.