The gunner's and leader's rules allow the determination of the safety limit by setting the safety angle on the gun and looking across the gun's sights. The safety limit is determined by the intersection of the new line of aim and the ground. When the feet of the friendly troops reach this point the fire must be lifted or shifted.
(1) Gunner's rule. The gunner's rule is used to determine the safety limit when the range to the target is 850 meters or less and friendly troops are at least 350 meters in front of the gun position (see figure 6-25). The gunner applies this rule unless the safety limit has been determined and announced by the platoon or section leader. The rule is as follows:
• Lay the gun on the target with the sights set to hit the target. The range to target must be determined with the most accurate means available.
• Without disturbing the lay of the gun, set the line of aim. For the M240G, set the sight on 1,500 meters. For the M2 .50 cal, set the sight on 1,600 meters.
• Look through the sights and note the point where this new line of aim strikes the ground. This point is the safety limit. When the feet of the friendly troops pass this point, overhead fire must be ceased or shifted. It is not safe to continue firing when friendly troops have passed this point.
• Gunners report safe (friendly troops are not past the safety limit) or not clear (friendly troops are past the safety limit) to indicate whether or not it is safe to fire. The gunner will report the location of the safety limit to the squad leader.
• Relay the gun back on to the target ensuring that the proper range to the target has been reset on the sights.
(2) Leader's Rule. The leader may want to orient his gunners on the safety limit using an identifiable terrain feature. The leader's rule is used to determine if that terrain feature selected by the leader can be used as the safety limit. The rule is as follows:
• The leader selects an easily identifiable terrain feature to which he believes friendly troops can advance safely.
• The gunner(s) lays the gun on the target with the sights set to hit the target. The range to the target must be determined with the most accurate means available.
• Set the line of aim for the M240G. Leave the sight set to the target range. Using the T&E depress the muzzle of the gun by a number of mils equal to the range to target in hundreds of meters, plus an extra 20 mils. Example: Target range = 1,100 meters. Depress the muzzle by 11 mils (one mil equals one click on the elevating hand wheel) and then depress the muzzle another 20 mils for a total of 31 mils.
• Set the line of aim for the M2 .50 cal. Set the sight on 1,600 meters or the range to the target plus 500 meters, whichever is greater. Under no conditions should the sight be set less than 1,400 meters.
• Note the point where the new line of aim strikes the ground.
- If the line of aim intersects the selected terrain feature, the selected feature is safe to use as the safety limit. Example: If the unit leader selected the center of the open area between the clumps of trees (A and B) in figure 6-26 as the terrain feature that he wanted to use as the safety limit then he could use that feature
Was this article helpful?