Figure 14-13.--Preparation for firing.
cannon one-fourth turn, so the handle is in an upward
mechanism to the left or counterclockwise to move the
elevating mechanism to the right, until it is vertical.
position (fig. 14-13, views A and B).
Now, remove the sight unit (M64/M64A1) from its case.
Loosen the knob on the biped, and swing it
Press the latching lever while installing the sight unit on
downward. Open the collar. There are two saddles on
the biped. Release the latching lever and check to see
the M225 cannon for positioning the biped. The upper
that the sight unit is firmly locked to the biped. The
saddle is used for elevations of 1,000 roils or less and
gunner sets the deflection scale at 0 mils and the
the lower saddle for elevations greater than 1,000 roils.
elevation at 1,000 mils. He then centers the elevation
(The upper saddle must be used for boresighting this
bubble and cross-levels the mortar. The mortar is now
weapon). Place the upper or lower saddle of the cannon
mounted and ready to be laid.
into the collar of the biped (fig. 14-13, view C). The
When more than one mortar is to be used for a
handle and firing mechanism assemblies are straight-up
mission, it is important that they be mounted and laid
on the top of the barrel. Close the collar and swing the
parallel. This ensures proper target coverage and
knob into place and tighten. Hold the barrel in a vertical
accurate destruction of targets when they are engaged.
position, and pull the legs of the biped up to unlatch and
swing out (fig. 14-13, view D). Unfasten the hook and
LAYING A MORTAR USING THE
cable. Loosen the coarse cross-leveling nut and spread
the legs. When the biped is attached to the upper saddle,
set the feet about 1 1/2 feet in front of the baseplate.
When the biped is attached to the lower saddle, set the
Several methods are used to lay mortars parallel.
feet about 1 foot in front of the baseplate. Press the biped
The most rapid, but the least accurate, method is by
feet firmly into the ground (fig. 14-13, view E). With the
using a compass. In this method the section leader stands
coarse cross-leveling nut still loose, adjust the
approximately 6 feet behind the mortar and sights
cross-leveling mechanism until the elevating
through the compass at a given direction. The section
mechanism is nearly vertical. Cross-leveling removes
leader then directs the gunner to move the lay of the
cant from the weapon. Hand tighten the nut. Adjust the
barrel left or right until the barrel and the sight wire of
fine cross-leveling nut clockwise to move the elevating
the compass are lined up. At this time the gunner