Description
U.S. Army Sight, Infinity M44 for M103A1/M103A2 120mm Gun Tank, FSN 1240-611-6492
The U.S. Army Sight, Infinity M44, identified by FSN 1240-611-6492, is a Cold War-era optical fire-control instrument used with the 120mm Gun Tank M103A1 and later M103A2 heavy-tank fire-control systems.
Mounted near the gunner’s M29 Periscope, the M44 projected an illuminated aiming ring into the periscope’s wide-angle unity viewing window. This allowed the gunner to aim the tank’s coaxial .30-caliber machine gun while keeping a broad view of the target area.
Despite the name “Infinity Sight,” the M44 is not a magnifying telescope. It is a fixed-focus collimating sight that projects its aiming image so it appears at optical infinity.
Historical Significance
The M103 family was developed during the early Cold War as the United States’ heavy 120mm gun tank. Its large turret carried the powerful M58 120mm cannon along with coaxial machine-gun armament and an advanced optical and mechanical fire-control system.
The improved M103A1 used the M15 stereoscopic rangefinder, M14 ballistic computer, M29 gunner’s periscope, M102 articulated telescope, and M44 Infinity Sight as part of its fire-control equipment.
The M44 had a specialized role within this system. Instead of providing a magnified view for the main gun, it projected a simple illuminated aiming ring into the wide-angle window of the M29 periscope. The gunner could therefore engage closer targets with the coaxial machine gun without giving up the broad field of vision provided by the unity window.
The M103A2 continued the heavy-tank family into the 1960s. Equipment from these tanks represents the final generation of American heavy-tank development before the main battle tank concept replaced the separate light, medium, and heavy tank classes.
What This Item Is and Does
The M44 contains a light source, reticle, and collimating optical system inside its compact housing.
When illuminated, the sight projects a circular aiming ring into the gunner’s M29 periscope. The projected image appears over the outside scene rather than requiring the gunner to look through a separate magnifying eyepiece.
This design allowed the gunner to:
- Maintain the M29 periscope’s wide-angle view
- Track nearby or moving targets
- Aim the coaxial .30-caliber machine gun
- Adjust the projected ring in elevation and azimuth during alignment
The projecting alignment pins and heavy mounting flange locate the M44 accurately on its bracket inside the turret.
This is the M44 Infinity Sight itself. It is not the M29 periscope, M102 telescope, M15 rangefinder, ballistic computer, or complete M103 fire-control system.
Key Features
- Official nomenclature: Sight, Infinity
- Model: M44
- Development designation: T159
- Federal Stock Number: 1240-611-6492
- Equipment class: Tank fire-control optical instrument
- Primary application: M103A1 120mm Gun Tank
- Later application: M103A2 120mm Gun Tank
- Associated gunner’s optic: Periscope M29
- Primary function: Coaxial machine-gun aiming
- Display type: Illuminated projected aiming ring
- Optical type: Fixed-focus collimating/infinity sight
- Magnification: None
- Alignment: Adjustable in elevation and azimuth
- Mounting: Heavy flange with locating/alignment pins
- Technical manual: TM 9-1240-248-35
- Visible serial number: Appears to be 218
- Included: One M44 Infinity Sight
A related version, the M44C, was later cataloged under FSN 1240-676-2181. Army maintenance publications cover both M44 and M44C sights.
Why This Item Matters
The M44 is an unusual piece of American tank fire-control history. Unlike a conventional scope, it worked with another optical instrument by placing its aiming image directly into the gunner’s periscope view.
That makes it a good example of the complex mechanical and optical systems used before modern electronic sights and digital fire-control computers became standard.
Identified M103 fire-control components are also difficult to find after removal from the tank. The model designation and Federal Stock Number make this sight useful for restoration planning, museum interpretation, and technical study.
About This Item
The identification plate marks the unit as SIGHT, INFINITY M44 with FSN 1240-611-6492. The serial number appears to read 218.
The boxed optical head contains the sight’s illumination, reticle, and collimating components. The projecting alignment pins and mounting flange are part of the original turret installation.
Optical clarity, reticle illumination, electrical components, adjustment mechanisms, internal completeness, and alignment have not been tested or verified.
This listing is for the M44 Infinity Sight only. The M29 periscope, mounting bracket, wiring, M102 telescope, M15 rangefinder, M14 ballistic computer, tank, and other fire-control components are not included.
This M44 Infinity Sight should not be confused with the M44 155mm self-propelled howitzer. The shared “M44” designation is only a model-number coincidence.
Ideal For
- M103A1 restoration projects
- M103A2 heavy-tank displays
- U.S. Cold War armored-vehicle collections
- Tank fire-control collections
- M29 periscope displays
- Military optics collections
- Coaxial machine-gun sight displays
- U.S. Army museums
- Heavy-tank exhibits
- Technical-reference collections
- Educational and historical displays
Approx length 7", Approx width 6", Approx height 4", Approx weight 2 lbs.
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.
Please visit our page about order lead times here: Order Lead Times