Product Overview: Periscope M42
NSN: 1240-01-067-0687
P/N: 7645543

Description
Periscope M42 is mounted above the cradle on the upper right-hand portion of the howitzer mount and is used with the elbow telescope M118C (T176E2) on Howitzer, Medium, Self-Propelled: 155MM, M109 (T196E1). It provides a clear field-of-view when the gun muzzle brake is used. The periscope consists of two clear windows, a stationary mirror, and an adjustable mirror mounted in a housing.

The windows are mounted in the housing and secured with sealing compound. They pass the image to and from the mirrors with minimum optical distortion. The stationary mirror is cemented to a cover which is mounted on the left side of the housing. The adjustable mirror is secured to a cover assembly which is mounted on the right side of the housing. The cover assembly contains provisions for adjusting the position of the mirror to obtain minimum image tilt and collimation.