MIL-M-48557, MILITARY SPECIFICATION: MOUNT, TELESCOPE AND QUADRANT - M171A1 (15-MAY-1990) [S/S BY MIL-DTL-48557A]

MIL-M-48557, MILITARY SPECIFICATION: MOUNT, TELESCOPE AND QUADRANT - M171A1 (15-MAY-1990) [S/S BY MIL-DTL-48557A]., This 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.