Description
U.S. M100 Panoramic Telescope for M53 and M55 Self-Propelled Artillery
Item Overview
This U.S. M100 Panoramic Telescope is an artillery fire-control instrument documented for the M53 155mm Self-Propelled Gun and M55 8-Inch Self-Propelled Howitzer. The identification plate is clearly marked “TELESCOPE PANORAMIC M100.” Mounted at the gunner’s station, the telescope provided a precise aiming reference for indirect-fire missions. Its long optical tube, panoramic head, eyepiece, and lower control housing form the distinctive M100 configuration shown in U.S. Army technical material.
Identification and Features
The M100 was a 4-power panoramic telescope with a 10-degree field of view. Its reticle had horizontal graduations at 5-mil intervals, with numbering at 50-mil intervals. The telescope included azimuth and elevation controls, a coarse azimuth scale, an azimuth counter, and a counter-reset control. Army manuals show it installed in the M99C or M99A1C telescope mount. The separate M99 telescope handled direct-fire sighting within the same general fire-control installation.
- Official designation: Telescope, Panoramic, M100
- Plate marking: TELESCOPE PANORAMIC M100
- Type: Indirect-fire artillery sight
- Magnification: 4 power
- Field of view: 10 degrees
- Elevation adjustment: -300 to +300 mils
- Reticle graduations: 5-mil intervals
- Documented mounts: M99C and M99A1C
- Verified applications: M53 and M55 self-propelled artillery
Historical Background
The M100 belongs to the generation of artillery fire-control equipment developed for the U.S. Army’s post-World War II self-propelled weapons. These enclosed vehicles required compact sights that could be operated from inside the fighting compartment while providing accurate directional control for indirect fire. The M100 was formally included in the fire-control requirements for the M53 and M55 under military specification MIL-F-14552, dated June 30, 1957. It served as the panoramic sight within a coordinated system of telescope mounts, elevation controls, and direct-fire instruments.
End-Item Application
The documented end-item applications for the M100 are the M53 155mm Self-Propelled Gun and the M55 8-Inch Self-Propelled Howitzer. The M53 carried the 155mm Gun M46, while the M55 carried the larger 8-inch, or 203mm, Howitzer M47. Both vehicles used closely related turret and fire-control arrangements, allowing the M100 panoramic telescope to serve in either installation. This example is marked M100 and is cataloged here only with its verified M53 and M55 applications.
How It Worked
The M100 was secured in an M99C or M99A1C mount at the gunner’s station. Its panoramic head allowed the line of sight to turn in azimuth while the eyepiece remained accessible to the gunner. During indirect fire, the crew received firing data and set the required direction on the sight. The gunner then viewed aiming posts or another established reference and traversed the weapon until the reticle was properly aligned. The azimuth-compensating mount helped correct sighting errors caused when the weapon’s trunnions were not level, supporting accurate direction settings on uneven ground.
Weapon-System Background
The M53 and M55 were heavy self-propelled artillery vehicles developed during the early Cold War. They shared a common armored chassis that used automotive features from the Patton tank family and placed the weapon in a large enclosed rear turret. Pacific Car and Foundry produced the vehicles for the U.S. military. The M53 provided mobile 155mm gun fire, while the M55 delivered the heavier effect of an 8-inch howitzer. Their protected fighting compartments and tracked mobility allowed heavy artillery to move with mechanized forces and operate without requiring a separate towed carriage.
History of Use
M53 and M55 vehicles served in American heavy-artillery units during the 1950s and 1960s. The M55 eventually took over many roles assigned to the M53, and U.S. Marine Corps M55 batteries later fired combat missions in Vietnam. During a typical indirect-fire mission, the panoramic telescope gave the gunner a repeatable directional reference while the crew applied firing data received from the fire-direction center. The sight remained aligned on aiming posts as the weapon was traversed between missions, helping the crew return to a known direction and apply later corrections accurately.
Condition
The identification plate remains present and clearly marked “TELESCOPE PANORAMIC M100.” The long optical tube and lower eyepiece and control housing retain the recognizable M100 exterior configuration. Please review the inventory photographs for the finish, markings, included fittings, and overall condition of the available examples.
Ideal For
This original military panoramic telescope is suitable for completing an M53 or M55 fire-control display, restoring a period self-propelled artillery vehicle, or presenting the development of Cold War artillery sighting equipment. Its clearly marked model plate and documented end-item applications also make it a useful reference piece for military museums, armor collections, and artillery researchers.
- M53 or M55 restoration projects
- Self-propelled artillery displays
- Military optical-instrument collections
- Cold War and Vietnam-era exhibits
- Artillery fire-control research
Approx length 9", Approx width 7", Approx height 24", Approx weight 31lbs.
Pictures are stock images of our inventory. Unless otherwise noted, you will not be receiving the exact item shown in the pictures. The pictures are representative of the item’s general condition. The item you receive might be slightly better, or worse, condition than was shown in the pictures.
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