Description
Technical Manual (TM 9-1240-227-35P) for M20A1, M20A3, M20A3C, M20A3F, and M20A3G Periscopes 1963
This Technical Manual TM 9-1240-227-35P covers the M20A1, M20A3, M20A3C, M20A3F, and M20A3G Periscopes and is dated January 1964.
The publication is a field- and depot-maintenance repair-parts and special-tools reference for five members of the M20 family of armored-vehicle observation and direct-fire periscopes.
Historical Significance
The M20 series belonged to the postwar generation of U.S. armored-vehicle fire-control equipment developed from the T35 Periscope. M20-family instruments were used in vehicles including the M41 Walker Bulldog, M47 Patton, and M48 Patton tank families.
The basic design combined a wide-view observation channel with a magnified aiming channel and graduated reticle. Subsequent models adapted the periscope to different mounts, reticles, vehicle layouts, and weapon-system requirements while preserving the same general observation-and-sighting role.
Armored-Vehicle and Weapon-System Applications
The M20A1 was used in M41 and M41A1 76 mm Gun Tanks and appeared in M48-series 90 mm tank fire-control arrangements. The M20A3 continued the family in later tank installations.
The M20A3G served as the gunner's periscopic sight on the M50A1 Ontos, supporting the aiming of its six 106 mm M40A1C recoilless rifles. The range of covered variants makes this parts publication relevant to several distinct armored-vehicle restoration and research projects.
What This Manual Covers
This -35P publication identifies repair parts and special tools authorized for field- and depot-level support of the five listed periscope models. It supports component identification, requisitioning, stock control, and maintenance planning for the related optical instruments.
The manual provides Federal Stock Numbers for each complete periscope and organizes maintenance-supply information needed to distinguish shared components from model-specific parts.
Key Features
- Official publication number: TM 9-1240-227-35P
- Publication year: January 1964
- Manual type: field and depot maintenance repair parts and special tools list
- M20A1 Federal Stock Number: 1240-344-4645
- M20A3 Federal Stock Number: 1240-546-9580
- M20A3C Federal Stock Number: 1240-692-1325
- M20A3F Federal Stock Number: 1240-707-1265
- M20A3G Federal Stock Number: 1240-886-5889
Why This Manual Matters
The M20 variants can appear similar while using different assemblies, stock numbers, reticles, or installation details. TM 9-1240-227-35P preserves the official nomenclature needed to separate those variants and identify the correct maintenance parts.
It also documents the supply support behind a widely used family of Cold War armored-vehicle optics, complementing vehicle manuals that describe how the sights were operated within complete fire-control systems.
About This Manual
Published by Headquarters, Department of the Army in 1963, TM 9-1240-227-35P is a field- and depot-maintenance repair-parts and special-tools publication.
It covers the M20A1, M20A3, M20A3C, M20A3F, and M20A3G rather than the complete M20-series maintenance procedures found in TM 9-1240-227-34.
Ideal For
This manual is a strong fit for:
- U.S. Army technical-manual collectors
- M41, M47, and M48 tank restorers
- M50A1 Ontos restoration and research projects
- Military optical-instrument and fire-control researchers
- Armor museums and reference libraries
Approx length 8", Approx width 10", Approx height .2", Approx weight .2lbs.
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