Technical Manual (TM 9-1240-287-35P) for M53 Sight Unit July 1970

Technical Manual (TM 9-1240-287-35P) for M53 Sight Unit July 1970

Technical Manual (TM 9-1240-287-35P) for M53 Sight Unit, P/N 8245971 – July 1970

Item Overview

This original U.S. Army technical manual provides the direct-support, general-support, and depot maintenance repair-parts and special-tools list for the M53 Sight Unit, part number 8245971.

Issued in July 1970, this manual helped maintenance personnel identify and order the correct components needed to repair or rebuild the M53 mortar sight.

This listing is for the technical manual only. It does not include the M53 Sight Unit, mortar, carrying case, instrument light, tools, or other equipment.

About the M53 Sight Unit

The M53 combines two major components into one fire-control instrument:

• M109 Elbow Telescope, part number 8588780
• M128 Telescope Mount, part number 8245970

The M109 is a fixed-focus optical instrument with 4x magnification and a 10-degree field of view. It provides the line of sight used to aim a mortar.

The M128 holds the telescope in relation to the weapon’s elevation and deflection axes. Its scales, level vials, knobs, and locking controls allow the gunner to enter firing data and level the weapon.

The complete M53 Sight Unit weighs approximately 5.25 lbs. Related instrument-light equipment allowed its reticle and scales to be viewed during night operations.

Historical Background

The M53 entered service during the Cold War as a standard sight for U.S. mortar systems. Documented applications include the 81-mm M29/M29A1 mortar and the 4.2-inch M30 mortar.

These weapons were also used in armored mortar carriers. The M125 series carried the 81-mm mortar, while the M106 series carried the 4.2-inch M30.

Published in July 1970, this repair-parts manual dates from the Vietnam War era. Mortars provided mobile, high-angle fire support, making accurate sighting equipment and dependable replacement parts essential.

The M53 family remained in service for decades and was later joined by the improved M53A1.

Identification

• Manual number: TM 9-1240-287-35P
• Equipment: Sight Unit M53
• Publication date: July 1970
• Publication type: Repair Parts and Special Tools List
• Maintenance levels: Direct support, general support, and depot
• M53 Sight Unit
  • Part number: 8245971
  • NSN: 1240-00-856-9452
• M109 Elbow Telescope
  • Part number: 8588780
  • NSN: 1240-00-823-5612
• M128 Telescope Mount
  • Part number: 8245970
  • NSN: 1240-00-823-5613
• Documented applications: M29/M29A1 81-mm mortar and M30 4.2-inch mortar

Collector and Research Value

This manual is a useful parts-identification reference for original M53 components. It is well suited for mortar restoration projects, military-optics collections, museum archives, and Vietnam-era fire-control research.

Ideal For

• U.S. Army technical-manual collections
• M53 Sight Unit parts identification
• M29 and M29A1 81-mm mortar displays
• M30 4.2-inch mortar displays
• M106 and M125 mortar-carrier research
• Military optics and fire-control archives

Approx length 8", Approx width 11", Approx height .2", Approx weight .2lbs.

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