Description
Technical Manual (TM 9-1240-295-35P) for M138 Telescope Mount January 1970 FSN 1240-896-2240
U.S. Army Technical Manual TM 9-1240-295-35P for M138 Telescope Mount, January 1970, FSN 1240-896-2240
Item Overview
This U.S. Army technical manual is a repair-parts and special-tools reference for the M138 Telescope Mount, FSN 1240-896-2240. Issued as TM 9-1240-295-35P in January 1970, it helped military personnel identify and order components required for higher-level maintenance.
This listing is for the technical manual only. It does not include an M138 mount, elbow telescope, elevation quadrant, artillery weapon, tools, or replacement parts.
About the M138 Telescope Mount
The M138 was designed to hold and position an elbow telescope used for direct artillery fire. Early configurations supported the M116 and M116C Elbow Telescopes. The mount was later used with the M139 Elbow Telescope on updated M110A2 equipment.
The mount includes a support assembly, telescope clamp, bracket, adapter, and electrical system. Adjustment mechanisms allow the telescope’s elevation and deflection to be set and locked in position.
Vehicle power operates the instrument light for low-light and nighttime use. The mount does not provide a sight picture by itself; that function comes from the attached elbow telescope.
Documented Artillery Applications
The M138 mount was used with the M107 175-mm Self-Propelled Gun and M110 8-inch Self-Propelled Howitzer families.
On the M107, the M116C telescope and M138 mount formed part of the right gunner’s direct-fire equipment. The mount supported and positioned the telescope, while the M15 Elevation Quadrant helped establish the required elevation.
Historical Background
The first TM 9-1240-295-35P was issued in October 1962 as the M107 and M110 entered Army service. This January 1970 edition reflects the continued support of the M138 during the Vietnam War era.
Current parts information was important because wear or damage inside the mount could shift the telescope and reduce accuracy. Illustrated parts manuals helped repair facilities identify components as stock records and maintenance requirements changed.
The M138 remained in use on later M110 equipment, showing the long service life of its basic design.
Publication Details
- Manual number: TM 9-1240-295-35P
- Publication date: January 1970
- Subject: M138 Telescope Mount
- Federal Stock Number: 1240-896-2240
- Later NSN format: 1240-00-896-2240
- Part number: 8587500
- Manual type: Field-and-depot maintenance repair parts and special tools list
- Original associated telescopes: M116 and M116C Elbow Telescopes
- Later associated telescope: M139 Elbow Telescope
- Documented artillery systems: M107 and M110 families
- Primary role: Direct-fire telescope support and adjustment
- Item included: Technical manual only
Collector and Research Value
This Vietnam-era manual is a specialized addition to a U.S. Army technical-publication, artillery, or military-optics collection. Its parts information can assist with component identification, restoration research, and the study of Cold War fire-control equipment.
It is also useful for museums, historians, and collectors researching the M138 mount, M116C telescope, M107 gun, or M110 howitzer.
Ideal For
- U.S. Army technical-manual collections
- M138 telescope-mount parts research
- M107 and M110 artillery displays
- Cold War and Vietnam War collections
- Military-optics restoration references
- Museum and archival collections
Approx length 8", Approx width 11", Approx height .15", Approx weight .2lbs.
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