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MS9557-25
Military Standard Machine Bolt
Description
Fastener Length: 1-3/4", Thread: 1/4-28, Thread Length: 51/64", MS9557 series bolt
Specifications
| Extended Washer Diameter | 0.438 |
|---|---|
| Extended Washer Thickness | Between 0.060 inches and 0.070 inches |
| Fastener Length | 1.750 |
| Features Provided | Finished head |
| Grip Length | Between 0.940 inches and 1.000 inches |
| Hardness Rating | 248.0 brinell standard and 341.0 brinell standard |
| Head Height | 0.300 |
| Head Style | Double hexagon w/hole |
| Length | 1 3/4 |
| Material | Iron |
| Material Specification | Ams 5731 assn standard single material response |
| Min. Tensile Strength (psi) | 130000 pounds per square inch |
| Minimum Yield Strength | 85000 pounds per square inch |
| Surface Finish | 32.0 microinches bearing surface of head, 32.0 microinches grip, 32.0 microinches threads |
| Thread Class | 3a |
| Thread Diameter | 0.250 |
| Thread Direction | Right-hand |
| Thread Length | Between 0.750 inches and 0.810 inches |
| Thread Qty | 28 |
| Thread Qty Per Inch (tpi) | 28 |
| Thread Series | UNJF |
| Thread Series Designator | Unjf (fine thread with external controlled root radius) |
| Thread Size | 1/4 |
| Width Between Flats | Between 0.305 inches and 0.313 inches |
Cross-reference
Similar parts
Parts with matching key dimensions — often from a different standards family. Candidates for comparison only; verify the full specification before substituting.
- MS9557-26 MS 1/4-28 · 0.073 in · Double hexagon w/hole · Iron
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Catalog data updated 2026-07-05. Report a data error