Description
U.S. Army Technical Manual TM 9-1290-262-35 for M2 Aiming Circle, June 1960
Item Overview
This U.S. Army technical manual covers field-and-depot maintenance for the M2 Aiming Circle. Issued as TM 9-1290-262-35 on June 20, 1960, it was prepared for trained personnel responsible for the inspection, repair, adjustment, and testing of this precision fire-control instrument. This listing is for the technical manual only. It does not include an aiming circle, tripod, protective cover, instrument light, plumb bob, weapon, or other equipment.
Publication Details
This manual documents the higher-level maintenance procedures used to keep the M2 Aiming Circle accurate and ready for field service.
- Manual number: TM 9-1290-262-35
- Publication date: June 20, 1960
- Equipment: M2 Aiming Circle
- Manual type: Field and depot maintenance
- Equipment class: Artillery fire-control and surveying instrument
- Later stock number: NSN 1290-00-614-0008
- Issuing authority: Headquarters, Department of the Army
- Country of origin: United States
- Item included: Technical manual only
Manual Coverage
The “35” suffix identifies this as a field-and-depot maintenance publication. It supported work beyond normal operator and organizational care. Its subject matter includes inspection, troubleshooting, disassembly, cleaning, repair, reassembly, adjustment, calibration, and final testing. This level of maintenance was important because small errors in the aiming circle could affect the alignment of an entire artillery battery or mortar section.
About the M2 Aiming Circle
The M2 Aiming Circle is a portable optical and mechanical instrument used to measure precise azimuth and elevation angles from a selected reference line. Its main parts include a four-power elbow telescope, magnetic compass, graduated scales, micrometer controls, leveling screws, and spirit levels. The instrument is placed on a tripod and carefully leveled before use. It could then be used to establish direction, measure angles, and align indirect-fire weapons.
Equipment Features
The M2 provided unlimited azimuth rotation and used a complete 6,400-mil circle for measuring direction. Its telescope offered four-power magnification and a 10-degree field of view. The original M2 could measure up to 800 mils of elevation and 400 mils of depression. Circular and tubular levels supported accurate setup, while micrometer controls allowed the operator to make fine adjustments.
- Azimuth rotation: Unlimited through 6,400 mils
- Maximum elevation: 800 mils
- Maximum depression: 400 mils
- Telescope magnification: 4 power
- Field of view: Approximately 10 degrees
- Common supporting equipment: M24 tripod and M51 instrument light
Role in the Weapons System
The M2 was general fire-control equipment and was not made for only one weapon. Artillery and mortar units used it to place several weapons on the same firing azimuth. During reciprocal laying, the aiming-circle operator and weapon crews exchanged angle readings until the sights and weapon tubes were correctly aligned. This allowed a battery or mortar section to deliver coordinated indirect fire when crews could not see the target.
Historical Background
The M2 was documented in U.S. Army service by the mid-1950s and became an important surveying and fire-control instrument during the early Cold War. This June 1960 manual was issued when the Army was expanding its mobile artillery forces and maintaining a mix of conventional guns, howitzers, and mortars. Reliable optical instruments remained essential even as radar, electronic computers, and other advanced fire-control equipment entered service.
History of Use
Artillery and mortar personnel used the M2 while preparing firing positions, establishing grid or magnetic direction, aligning weapons, measuring horizontal and vertical angles, and performing field-survey work. Its portable design allowed crews to use it at fixed bases or temporary positions. The M2 later served alongside the improved M2A2, which increased the maximum elevation range. A newer Army maintenance manual replaced TM 9-1290-262-35 in 1982, showing that the M2 remained supported for more than two decades after this edition was published.
Collector and Research Value
TM 9-1290-262-35 is a useful reference for studying the internal construction, maintenance, and calibration of the M2 Aiming Circle. It also documents early Cold War artillery-support practices before later manuals combined coverage of the M2 and M2A2. This specialized publication is well suited for technical-manual collections, museum research, equipment restoration, and military fire-control displays.
Condition
This vintage military technical manual may show cover wear, edge wear, folds, yellowing, stains, writing, stamps, punched holes, loose pages, or other signs of age and storage. Printing details and condition may vary between available copies. Please check the pictures for the general condition of the item.
Ideal For
This technical manual is a specialized reference for collectors, researchers, restorers, and museums interested in artillery surveying and indirect-fire equipment.
- U.S. Army technical-manual collections
- M2 Aiming Circle restoration references
- Artillery and mortar fire-control research
- Cold War military-equipment displays
- Military optics and surveying collections
- Museum and archival research
Approx length 8", Approx width 10", Approx height .3", Approx weight .5lbs.
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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