MIL-DTL-48557 Mount, Telescope And Quadrant - M171A1This specification covers the Mount, Telescope and Quadrant: M171A1 which supports the Telescope, Panoramic: M137A2 and Quadrant, Fire Control: M17A1 for use on the M777 and M198 series of howitzers. The mount provides adjustments in pitch and compensates for angles of cant when laying the guns for indirect fire.

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MIL-DTL-48557B

Figure 3. Mount rigidity wall target.

4.7.11 Azimuth correction. Position the mount as specified in 4.7 and install

sighting device, 10549200, to the telescope mounting surface with its line of sight parallel

to the telescope locating keys. The pitch and cross level vials shall be set at zero. Use

inspection aid, 8658940, on a cross-leveled inspection aide support assembly, 10553898,

for all elevation readings throughout the azimuth correction test. Position a wall target