## Full

1600- 2400 (RECEDING LEG)

3/4

Figure 17S. Amount of lead necessary for various angles Of approach.

Figure 17S. Amount of lead necessary for various angles Of approach.

point is called "full lead." Figure 172 is baaed on targets at or near midpoint.

b. Figure 173 give» the fraction of full lead necessary for various angles of approach.

c. To simplify the lead problem, the following rules may be used as a guide in determining initial leads:

(1) Crossing courses.

(а) Open fire with a %-full estimated lead, when the target is on the approaching or receding leg.

(б) Open fire with a full estimated lead, when the target is at midpoint»

(2) Directly at the gun courses. Open Are with no lead.

(8) All courses. Observe tracers and make corrections accordingly.

Section V, TARGET ENGAGEMENT

165. Sequence of Events

The following are the gunner's actions to bring the target under Are:

o. Estimates the necessary lead.

b. Elevates his weapon until the axis of the bore is alined with the target-course line, and applies the estimated lead.

c. Opens Are, and observes only the tracers in the vicinity of the target (para 167—170).

d. Elevates or depresses the gun until line shots are obtained.

e. Corrects his lead until hits are obtained, using tracer observation.

166. Techniques a. The machinegunner fires continuously throughout the engagement. Since the large amount of smoke created by continuous fire tends to restrict visibility, the gunner keeps his head and eyes high above the gun to observe the tracers. When there is doubt as to the tracers positions, he increases his lead. It is important that the gunner initially opens fire with an adequate lead and, once established, his tracking is not reversed. If his initial lead is too great, the tracking rate is slowed and he allows the target to catch up with his tracers.

b. The dispersion cone is excessive when the gun is fired as a free weapon. To offset this, the gunner seizes the grips firmly with both hands and braces the gun with his body. When firing from the M6S mount, the gunner stands erect and makes changes in elevation by moving his hands and arras up and down. For a change in azimuth he shifts his feet and moves around the mount. The gun is fired with the left hand by depressing either one of the upper and lower firing grips on the left side of the frame. The upper firing grip is used for fire at medium and high angles of elevation. The lower firing grip is used for fire at low angles of elevation.

Section VI. TRACER OBSERVATION

167. General

To make adjustment during firing, the gunner must know the location of the round with respect to the target. Tracer ammunition provides this information. However, the gunner must be trained to sense tracers correctly to produce a hit. Where target courses and target speeds can be fixed, valid lead data is obtained from a tracer observer located down-course from the gun <FM 44-2). Under normal conditions, valid sensings are obtained only if the tracer observer is stationed as close to the gun as possible

168. Principles o. Superimposition. In observing tracers, the machinegunner utilizes the principle of superimposition. By alining the tracer with the target, the gunner compares the range from his eye to the target and from his eye to the tracer. In figure 174, it can be seen that regardless of the range to the target, he can compare the range to the tuacer, and the range to the target as long as the two are superimposed. Lead can be judged on the basis of these comparisons. Because of the common tendency of gunners to attempt to judge lead when tracers are not alined with the target, the first basic principle of tracer observation must be stressed. Fulfill the line requirement before attempting to judge lead.

b. Localized Vision. In figure 175, the tracer is shown as a single spot in the sky, moving directly away from the gunner's eye. In actual practice, the tracer does not appear as a fixed spot, but rather as a curved path (fig 175). This apparent curvature of the tracer path is called the illusion

A. NOT ALINED CANNOT B ALINED ON NEAR C. ALINED ON FAR

COMPARE RANGES. SIDE, TRACER RANGE SIDE. TRACER RANGE

IS LESSER. ,8 GREATER.

A. NOT ALINED CANNOT B ALINED ON NEAR C. ALINED ON FAR

COMPARE RANGES. SIDE, TRACER RANGE SIDE. TRACER RANGE

IS LESSER. ,8 GREATER.

Figur* Sup^ritnporiKon.

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