Description
U.S. Military Sight, Periscope M28 (T46) — Serial Number 13032
The U.S. Military Sight, Periscope M28 (T46) — Serial Number 13032 is a 1.5-power commander's cupola machine-gun sight identified by part number 8270601 and NSN 1240-00-346-8735. The unsuffixed M28 was used with the M48A1 and M48A2 90 mm gun tanks, the M59 armored personnel carrier with M13 cupola, and the M84 4.2-inch self-propelled mortar carrier.
On those Army vehicles, the M28 provided a protected optical line of sight for the cupola-mounted .50-caliber machine gun. Navy documentation also lists the M28 for the Mk 48 and Mk 49 20/40 mm gun mounts. It is a cupola or gun-mount sight, not a tank main-gun sight.
Historical Significance
The M28 is an early Cold War, mid-1950s fire-control optic. Its moving-prism design let an operator aim a linked weapon while viewing through a protected eyepiece that remained stationary.
Army maintenance publications document the M28 separately from the later M28C and M28D variants. TM 9-1240-239-35, dated 17 August 1960, describes its optical and mechanical design. TM 9-1240-239-35P, dated 5 January 1970, identifies the M28 as assembly 8270601 and illustrates it in Figure 1.
M28, M28C, and M28D Applications
The unsuffixed M28 is the version documented for the M48A1, M48A2, M59 with M13 cupola, and M84. The M28C was listed for later applications that included the M48A2C, M48A3, M60, M60A1, M67A1, and M67A2. The M28D was listed for the M132 and M132A1.
These suffix distinctions matter to collectors and restorers. The offered unsuffixed M28 should not be cataloged as an M60 sight.
What This Item Is and Does
The U.S. Military Sight, Periscope M28 (T46) — Serial Number 13032 is a monocular periscopic sight. A mechanical sight link connected the weapon installation to the side coupling arm. As the linked weapon elevated or depressed, tape-connected pulleys moved an internal prism while the eyepiece remained stationary.
Army specifications list 1.5-power magnification, a 48-degree field of view, and line-of-sight movement from 15 degrees depression to 60 degrees elevation. The design was sealed against moisture and filled with dry nitrogen.
Key Features
- Official nomenclature: Periscope, Tank M28 / Periscope, Armored Vehicle
- Model M28 (T46) with serial number 13032
- Sight assembly part number 8270601
- National Stock Number 1240-00-346-8735
- Eyepiece assembly marked 8270647
- Frankford Arsenal design-authority code 19200
- 1.5-power optical system with 48-degree field of view
- Line-of-sight movement from 15 degrees depression to 60 degrees elevation
- Army applications: M48A1, M48A2, M59 with M13 cupola, and M84
- Navy applications: Mk 48 and Mk 49 20/40 mm gun mounts
Why This Item Matters
The M28 is a substantial armored-vehicle and gun-mount optical assembly with documented use across several early Cold War systems. Its moving-prism arrangement shows how a linked weapon could be aimed through a stationary, protected eyepiece.
The model, serial number, sight assembly number, and visible eyepiece number make this example especially useful for military-optics collections, museum displays, restoration reference, and technical study.
About This Item
The offered item is the U.S. Military Sight, Periscope M28 (T46) — Serial Number 13032, part number 8270601 and NSN 1240-00-346-8735. Army applications include the commander's cupola installations on the M48A1 and M48A2 tanks, the M59 armored personnel carrier with M13 cupola, and the M84 self-propelled mortar carrier, where the sight served the cupola-mounted .50-caliber machine gun. The Navy also documented the M28 for the Mk 48 and Mk 49 20/40 mm gun mounts.
The exposed eyepiece is marked 8270647. Its rubber eyeshield is missing, and no M104A1/M104A2 periscope mount is shown with this example. The marked warning, DO NOT SNAP COUPLING ARM, refers to the spring-loaded return mechanism; Army inspection guidance directs that pressure on the arm be released gradually.
Ideal For
This item is a strong fit for:
- M48A1 and M48A2 tank collections and restoration reference
- M59 and M84 armored-vehicle research
- U.S. military optics collections
- Navy gun-mount equipment research
- Museum and educational displays
- Early Cold War fire-control exhibits
- Film and prop department reference
Approx length 8", Approx width 5.5", Approx height 14.25", Approx weight 8.1lbs.
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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