Description
U.S. 152mm Gun Breech-Boresight Adapter No. 8625910
Item Overview
This U.S. military breech-boresight adapter was made for use with a 152mm gun system. It carries part or drawing number 8625910 and was designed to support an optical viewer on the centerline of the gun bore. The adapter helped crews check the alignment of the gunner’s telescope and periscope before firing. This listing is for the mechanical adapter only. It is not the telescope, binocular, or complete boresight set.
Identification and Features
The adapter has a cylindrical section that fits into the open breech of a 152mm gun. Its rails, brackets, and adjustment points position a separate optical viewer in line with the barrel. The construction and military part number identify it as specialized fire-control support equipment rather than part of the gun’s firing mechanism.
- Item type: Breech-boresight or breechscope adapter
- Part or drawing number: 8625910
- Caliber application: 152mm gun system
- Country of origin: United States
- Original purpose: Alignment of the gun bore, telescope, and periscope
- Installation point: Open breech of the gun
- Optical viewer: Not included
- Muzzle boresight: Not included
- Status: Non-energetic mechanical military equipment
Original Boresighting Function
To boresight the weapon, the cylindrical end of the adapter was inserted into the open breech. A separate optical viewer was positioned over the adapter so the crew could look through the centerline of the barrel. Crosshairs or a cord-type boresight were placed across reference marks at the muzzle. The crew aimed the bore at a clear distant point and then adjusted the gunner’s telescope and periscope until their sight pictures matched the bore. This process connected the aiming instruments to the actual direction of the barrel.
Probable M551 Sheridan Application
152mm adapter is for the M81 or M81E1 gun-launcher installed on the M551 Sheridan. The Sheridan’s documented breech-boresight procedure matches the form and intended use of this equipment. The design also fits the general period of the Sheridan program, which entered Army service during the 1960s. Because no surviving record has been found that directly lists number 8625910 for the M81, M81E1, or M551, this vehicle assignment should be considered probable rather than confirmed.
Possible M60A2 Application
The M162 152mm gun-launcher fitted to the M60A2 is another possible application. The M162 belonged to the same general generation of U.S. gun-launcher technology and also required accurate alignment of its bore and fire-control sights. Available documentation has not directly connected number 8625910 to the M162 or M60A2. This possibility is included for historical reference and should not be presented as a verified fit.
152mm Gun-Launcher History
The M81 gun-launcher gave the lightweight M551 Sheridan an unusually large main armament. It could fire conventional 152mm ammunition at closer targets and launch the MGM-51 Shillelagh guided missile against armored vehicles at longer ranges. A related M162 gun-launcher was installed on the M60A2. These systems combined a large-caliber gun with guided-missile equipment, making accurate alignment of the bore, telescope, periscope, and fire-control system especially important.
History of Use
The M551 Sheridan entered U.S. Army service in the late 1960s and saw combat in Vietnam. Sheridans later served during Operation Just Cause in Panama and during Operations Desert Shield and Desert Storm. Crews used boresighting equipment during sight checks, maintenance, weapon preparation, and training. These checks helped confirm that a sighted target matched the true direction of the gun barrel. The M60A2 served mainly during the 1970s and early 1980s, but the exact service history of this individual adapter is unknown.
Missing Components
The optical viewer and muzzle-boresight components are missing. This adapter cannot form a complete boresighting system by itself. A telescope, binocular, muzzle crosshairs, storage case, manual, vehicle, gun, and other fire-control equipment are not included unless specifically stated. Buyers should treat this as a collectible mechanical component rather than a complete or tested alignment instrument.
Condition
This is a used military-surplus item that may show scratches, worn finish, oxidation, discoloration, dents, tool marks, dirt, or other signs of service and storage. Adjustment parts may be stiff, incomplete, or untested. No claim is made that the adapter remains calibrated or suitable for operational boresighting. Markings and minor details may vary among available examples. Please check the pictures for the general condition of the item.
Ideal For
This uncommon 152mm fire-control accessory is well suited for collections and exhibits covering Cold War armor, military optics, tank maintenance, and U.S. gun-launcher development.
- M551 Sheridan displays
- M81 and M81E1 gun-launcher collections
- M60A2 and M162 research displays
- Cold War armored-vehicle exhibits
- Military optical-equipment collections
- Fire-control and boresighting displays
- Military museums and educational exhibits
- U.S. Army maintenance-tool collections
Approx length 32", Approx width 6", Approx height 6", Approx weight lbs.
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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