Description
U.S. Army XM27 20mm M139 Gun-Charger Gearbox Guard, P/N 11619197
Item Overview
This U.S. Army protective guard was made for the gun-charger gearbox in the XM27 powered 20mm weapon cupola. The XM27 cupola carried the M139 automatic cannon on the M114A1E1 armored command and reconnaissance vehicle, which was later standardized as the M114A2. Army manual TM 9-1005-307-24P identifies this piece as item 5 in Figure 56 and lists it under part number 11619197. This is one guard only, not the complete gearbox, gun charger, cupola, cannon, or vehicle.
Identification and Features
The part number and stock numbers provide a confirmed identification. The original Federal Stock Number uses the 11-digit format found before the modern National Stock Number system. The later NSN adds the two-digit national codification code while keeping the same item identity. The carton markings place this example in a March 1969 military supply and preservation program.
- Official name: Guard
- Part or drawing number: 11619197
- Original FSN: 1005-021-2434
- Modern NSN: 1005-00-021-2434
- Manual reference: TM 9-1005-307-24P, Figure 56, item 5
- Assembly: XM27 gun-charger gearbox
- Weapon: 20mm M139 automatic cannon
- Vehicle: M114A1E1, later designated M114A2
- Package quantity: One guard
- Contract: DAAF03-68-C-0067
- Packaging date: March 1969
- Packaging marking: TYPE II CODE 8
Original Service Function
The gun charger helped place the M139 cannon's operating parts in the charged position so the weapon could be placed into service. Its gearbox transferred motion through a compact drive arrangement that included a chain, sprocket, shafts, and related hardware. Guard 11619197 covered part of that moving drive area. The guard helped protect the mechanism from contact, loose objects, and accidental damage while also reducing crew exposure to moving parts inside the crowded cupola. It was a protective component and did not serve as armor, a firing control, or a complete charging mechanism by itself.
Cupola, Weapon, and Vehicle Application
The XM27 was a powered commander's cupola built around the 20mm M139 automatic cannon. It gave the M114A1E1 much more firepower than the .50-caliber machine-gun installations used on earlier M114 and M114A1 vehicles. Powered traverse and elevation allowed the commander to aim the cannon from within the armored vehicle, while the cupola's feed, ejection, lubrication, charging, sighting, and safety systems supported weapon operation. This guard belongs specifically to the gun-charger gearbox group shown in the XM27 parts manual. It should not be confused with an exterior armor plate, ammunition-feed part, recoil component, or guard from the earlier M26 .50-caliber cupola.
Historical Background and Use
The U.S. Army developed the M114 family during the late 1950s and introduced it in the early 1960s as a small, low-profile vehicle for command and reconnaissance work. Early M114 vehicles served in Vietnam, where rough terrain, mines, and mechanical problems exposed serious limits in the design. The Army removed those vehicles from Vietnam, but the M114 family continued in units in the United States, Europe, Korea, and other locations. During the 1960s, the Army tested a Hispano-Suiza 20mm cannon on the M114 and developed the American M139 installation. The resulting M114A1E1 entered the supply system around 1969 and was later called the M114A2. Its XM27 powered cupola offered stronger armament, but the M114 family was still withdrawn from Army service during the 1970s. Combat use in Vietnam applies to the earlier M114 family; available records do not establish that this later XM27 guard or the M114A1E1/M114A2 20mm configuration served there.
Packaging and Marking Notes
The carton identifies one guard under Army contract DAAF03-68-C-0067 and carries a March 1969 packing date. That date records packaging or preservation and should not automatically be treated as the exact manufacture date. The marking TYPE II CODE 8 describes the military preservation and packing method rather than the model of the part. The period FSN 1005-021-2434 and modern NSN 1005-00-021-2434 refer to the same guard, and Federal Supply Class 1005 covers guns through 30mm and related components.
Condition
This is a surplus mechanical guard and may show scratches, finish wear, oxidation, storage residue, small dents, edge wear, or other signs of age and handling. The original carton may show fading, stains, tape, writing, creases, tears, or shelf wear from long-term storage. This listing is for one guard only; the mounting screw, gearbox, chain, sprockets, gun charger, cannon, cupola, and vehicle are not included unless specifically stated. Please check the pictures for the general condition of the item.
Ideal For
This confirmed XM27 component is a useful original part for collections and exhibits focused on Cold War armored reconnaissance vehicles, automatic-cannon systems, and U.S. Army technical development during the Vietnam era.
- M114A1E1 and M114A2 vehicle collections
- XM27 powered cupola displays
- 20mm M139 cannon exhibits
- Cold War U.S. Army collections
- Vietnam-era vehicle history displays
- Military museums and technical study collections
Approx length 7", Approx width 3", Approx height 1", Approx weight 0.6lbs.
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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