Emplace the baseplate by standing on it and rocking back and forth. Rotate the locking cap until the opening in the cap points in the direction of the target. Place the base of the cannon into the cap opening. Rotate the

Figure 14-13.-Preparation for firing.

cannon one-fourth turn, so the handle is in an upward position (fig. 14-13, views A and B).

Loosen the knob on the biped, and swing it downward. Open the collar. There are two saddles on the M225 cannon for positioning the biped. The upper saddle is used for elevations of 1,000 roils or less and the lower saddle for elevations greater than 1,000 roils. (The upper saddle must be used for boresighting this weapon). Place the upper or lower saddle of the cannon into the collar of the biped (fig. 14-13, view C). The handle and firing mechanism assemblies are straight-up on the top of the barrel. Close the collar and swing the knob into place and tighten. Hold the barrel in a vertical position, and pull the legs of the biped up to unlatch and swing out (fig. 14-13, view D). Unfasten the hook and 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 feet about 1 foot in front of the baseplate. Press the biped feet firmly into the ground (fig. 14-13, view E). With the coarse cross-leveling nut still loose, adjust the cross-leveling mechanism until the elevating mechanism is nearly vertical. Cross-leveling removes cant from the weapon. Hand tighten the nut. Adjust the fine cross-leveling nut clockwise to move the elevating mechanism to the left or counterclockwise to move the elevating mechanism to the right, until it is vertical. Now, remove the sight unit (M64/M64A1) from its case. Press the latching lever while installing the sight unit on the biped. Release the latching lever and check to see that the sight unit is firmly locked to the biped. The gunner sets the deflection scale at 0 mils and the elevation at 1,000 mils. He then centers the elevation bubble and cross-levels the mortar. The mortar is now mounted and ready to be laid.

When more than one mortar is to be used for a mission, it is important that they be mounted and laid parallel. This ensures proper target coverage and accurate destruction of targets when they are engaged.