Description
Technical Manual Change 1 (TM 9-1005-246-24) for 20mm M139 Automatic Gun August 1972 FSN 1005-999-0896
Add a focused piece of Vietnam War-era / Cold War armored vehicle armament documentation to your collection with this Technical Manual Change 1 for TM 9-1005-246-24 issued on November 1971. This change notice covers the 20mm Automatic Gun M139, listed with FSN 1005-999-0896, and is dated August 1972.
This is the Change 1 update only, not the full base manual. For collectors, it is a valuable companion piece for completing the technical publication history of the M139 20mm automatic gun.
Historical Significance
The 20mm M139 Automatic Gun was the U.S. service version of the Hispano-Suiza HS.820 / Oerlikon KAD 20mm autocannon family. The HS.820 family is documented as a 20x139mm autocannon, with M139 listed as the U.S. service designation.
In U.S. service, the M139 is especially connected to armored reconnaissance vehicle development. The M114A2 Command and Reconnaissance Carrier used the M139 in the powered XM27 cupola, giving the vehicle a major armament upgrade over earlier machine-gun-only configurations.
That makes this August 1972 Change 1 especially interesting. It belongs to the period when the Army was maintaining and updating documentation for vehicle-mounted 20mm cannon systems, powered cupolas, and Cold War reconnaissance platforms.
The M139 Automatic Gun Connection
The M139 represented a step toward heavier automatic cannon firepower on U.S. armored vehicles. It gave selected platforms a 20mm weapon suited for reconnaissance support, suppressive fire, and engagement of light targets.
The broader HS.820 / M139 family is associated with left- or right-hand belt-feed configurations and 20x139mm ammunition. That makes the M139 a strong subject for collectors focused on:
- 20mm autocannon systems
- M114A2 armored reconnaissance vehicles
- XM27 powered cupola components
- Vietnam War-era armored vehicle armament
- Cold War vehicle weapons development
- repair parts and special tools documentation
What This Change Covers
As Change 1 for TM 9-1005-246-24, this publication updated the Army’s maintenance and parts-reference manual for the 20mm M139 Automatic Gun.
Military technical manuals were official working documents intended to support identification, use, servicing, and field support of the equipment they covered, making them useful for collectors, historians, researchers, and restorers.
This manual change is especially relevant for:
- TM 9-1005-246-24 revision history
- M139 automatic gun maintenance documentation
- M139 repair parts and special tools research
- XM27 powered cupola reference collections
- M114A2 armored vehicle displays
- Cold War U.S. Army ordnance manual collections
- collectors completing an M139 technical manual set
Manual changes were working updates. They were often separated from base manuals over time, which makes surviving examples useful for completing a more accurate technical publication set.
Key Features
- Technical Manual Change 1 for TM 9-1005-246-24 issued November 1971
- Covers the 20mm Automatic Gun M139
- Dated August 1972
- Listed with FSN 1005-999-0896
- U.S. Army maintenance manual update
- Related to organizational, direct support, and general support maintenance documentation
- Includes repair parts and special tools list context
- Connected to the M114A2 Command and Reconnaissance Carrier
- Associated with the XM27 powered 20mm gun cupola
- Strong Vietnam War / Cold War armored vehicle armament collector subject
About This Manual Change
This listing is for Technical Manual Change 1 for TM 9-1005-246-24 issued November 1971, covering the 20mm M139 Automatic Gun, with FSN 1005-999-0896.
This listing is for the Change 1 update only unless otherwise stated. No complete base manual, automatic gun, cannon, cupola, armored vehicle, ammunition, tools, repair parts, storage case, or additional accessories are included unless specifically shown or noted.
Ideal For
This manual change is a strong fit for:
- 20mm M139 Automatic Gun collectors
- M114A1E1 and M114A2 vehicle reference collections
- XM27 powered cupola displays
- Vietnam War armored vehicle collections
- 20mm autocannon reference libraries
- U.S. Army ordnance manual collectors
- museum and archival reference displays
- collectors completing an M139 technical manual set
Approx length 11", Approx width 8", Approx height .1", Approx weight .1lbs.
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