The 107mm or 4.2" mortar used the graphical firing fan (GFF), while the 60mm and 81mm mortars used the M16 or M19 plotting boards
. Each of these devices are limited only by the operator's knowledge and skill.
Conventional Indirect Fire--This method is used when the mortars have been laid for direction and an FDC established with positions plotted on the M16 plotting board or the M-95 mortar fire control system.
He uses either the MFCS or the plotting board to refine the firing data based on the observer's corrections.
I cannot stress enough the importance of knowing the plotting board for manual computations of firing data.
Do not wait for a catastrophe prior to learning the plotting board. Always keep a plotting board set up with a modified observed firing chart.
In order for the squad leaders to set up their plotting boards
, the platoon leader must issue the "grid intersection" for the plotting board
, a direction of fire, a referred deflection, and the target location.
The M16 plotting board
allows the FDC to determine which guns will fire during the mission.
This manual is divided into four parts: Introduction and Fundamentals of Mortar Gunnery, Fire Direction Center, Mortar Ballistic Computer, and M16 and M19 Plotting Boards
. It provides guidance for soldiers in MOS 11C and their trainers on the employment of the 60mm, 81mm, 4.2-inch, and 120mm mortars.