Description
XM44 Periscope Pin
This XM44 Periscope Pin, identified by FSN 5315-825-1207 and Part Number MS16555-627, is a specialized military-surplus hardware component associated with the XM44 tank gunner’s periscope equipment family. For collectors of U.S. military optical-instrument parts, fire-control components, armored vehicle support hardware, and stock-numbered surplus items, this is a focused small component with strong catalog and reference value.
Public parts references list MS16555-627 under the modern NSN format 5315-00-825-1207, with the item identified as a Headless Straight Pin / Pin, Straight, Headless. The same references place it in FSC 5315 – Nails, Machine Keys, and Pins, confirming this as a hardware support component rather than a complete optical instrument, weapon, or ammunition item.
The XM44 Periscope
The XM44 Periscope belongs to the broader family of U.S. military fire-control optics, armored vehicle sighting instruments, and tank periscope equipment. A military specification amendment identifies the equipment as “Periscope, Tank: XM44”, placing the XM44 within the tank optical-instrument category.
A U.S. field manual reference describes the XM44 Periscope as the night sight for the Sheridan Tank when using conventional ammunition, mounted in the turret on the right side of the main gun. The same reference describes the XM44 as including a head assembly, body assembly, optical system, image intensifier tube, reticle projector system, and related accessory equipment.
For collectors, that gives this pin added appeal. It is a small but specific support component tied to a larger armored vehicle sighting and fire-control system, making it relevant to collections focused on XM44 periscope parts, Sheridan tank equipment, armored vehicle optics, military fire-control instruments, and U.S. surplus optical hardware.
The MS16555-627 Pin
The MS16555-627 Pin is best understood as a precision military-standard hardware item used where a small pin is required for alignment, retention, spacing, positioning, or assembly support within compatible equipment. Public NSN references describe 5315-00-825-1207 as a headless, cylindrically shaped straight pin used for aligning or transferring torque and/or thrust by fitting into corresponding holes.
Known reference details for MS16555-627 include:
- Item: XM44 Periscope Pin
- Part Number: MS16555-627
- Legacy FSN: 5315-825-1207
- Modern NSN Reference: 5315-00-825-1207
- NIIN: 00-825-1207
- Catalog Nomenclature: Pin, Straight, Headless
- Common Description: Headless Straight Pin / Dowel Pin
- Federal Supply Class: 5315 – Nails, Machine Keys, and Pins
- Item Name Code: 02390
- General Size Reference: 1/8 inch diameter x 1/2 inch length
- Typical Standard Reference: MS16555 / NASM16555
- Typical Material Reference: 400-series stainless steel
- Typical Finish Reference: Clear passivated
- Included Item: Pin only
Commercial mil-spec hardware references for MS16555-627 describe it as a 1/8 x 1/2 mil-spec dowel pin, commonly listed as 400-series stainless steel, clear passivated, and manufactured under the MS16555 / NASM16555 pin standard family.
What This Pin Supports
As an XM44 Periscope Pin, this item is best understood as a small support component for a larger optical and fire-control instrument assembly. It is not a complete periscope, not an image intensifier, not a sighting system, not a firearm, and not ammunition.
In practical collecting and display terms, a component like this is especially relevant for:
- XM44 periscope component collections
- armored vehicle optical-instrument displays
- Sheridan tank fire-control equipment reference collections
- U.S. military surplus hardware collections
- fire-control instrument restoration support
- museum exhibits on military optics and armored vehicle sighting systems
- collectors seeking P/N MS16555-627 / FSN 5315-825-1207
Because this is a small hardware component, buyers working on a specific restoration, repair, or display project should verify fitment against their own parts manual, periscope assembly, or technical documentation before purchase.
Historical and Technical Interest
Small components like this XM44 Periscope Pin help preserve the support side of military optical and fire-control equipment. Larger systems such as tank periscopes, sights, rangefinders, and night-vision instruments depended on many individual pins, screws, retainers, brackets, covers, plates, lenses, and optical components to remain complete and serviceable.
For collectors and historians, this pin is especially relevant to subjects such as:
- XM44 tank periscope components
- Sheridan tank sighting equipment
- U.S. armored vehicle fire-control optics
- military optical-instrument hardware
- MS16555 military-standard pins
- Cold War armored vehicle support components
- U.S. military maintenance and supply-system history
Because it carries both a recognizable MS part number and a legacy FSN, this pin has stronger catalog value than a generic unmarked hardware item. It helps document how even small military components were standardized, stocked, and referenced through the supply system.
About This Periscope Pin
This listing is for one XM44 Periscope Pin, identified as FSN 5315-825-1207 and P/N MS16555-627.
It is especially well suited for:
- XM44 periscope parts collectors
- U.S. armored vehicle optics displays
- Sheridan tank equipment reference collections
- military fire-control instrument collections
- museum and archival reference use
- restorers or display builders seeking correctly identified small components
- buyers seeking MS16555-627 / 5315-00-825-1207
This listing is for the pin only unless otherwise stated. No complete periscope, optical assembly, image intensifier, tank component, mount, tools, manuals, or additional accessories are included unless specifically shown or noted.
Why This Pin Matters
Many military collectibles focus on complete vehicles, weapons, optics, uniforms, or manuals. This item represents a different but equally important category: the small standardized hardware that helped keep military optical equipment assembled, maintained, and documented.
For collectors, it is a compact and highly specific component with direct XM44 Periscope association and clear FSN / P/N identification. For researchers, it provides a useful example of how small fire-control and optical-instrument parts were cataloged. For museums and displays, it helps show the detailed support hardware behind armored vehicle sighting systems.
Because this item is identified as an XM44 Periscope Pin with FSN 5315-825-1207 and P/N MS16555-627, it is a strong fit for anyone building a focused collection of U.S. military optical components, armored vehicle fire-control parts, or government-surplus cataloged hardware.
Ideal For
This periscope pin is a strong fit for:
- XM44 Periscope component collections
- Sheridan tank optical-equipment displays
- U.S. armored vehicle fire-control collections
- military surplus hardware collectors
- museum and archival display setups
- buyers seeking P/N MS16555-627 / FSN 5315-825-1207
Approx length .5", Approx width .1", Approx height .1", Approx weight .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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