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MS9557-20
Military Standard Machine Bolt
Description
Fastener Length: 1-3/8", Thread: 1/4-28, Thread Length: 47/64", MS9557 series bolt
Specifications
| Extended Washer Diameter | 0.428 inches minimum and 0.448 inches maximum |
|---|---|
| Extended Washer Thickness | 0.050 inches minimum and 0.070 inches maximum |
| Fastener Length | 1.365 inches minimum and 1.385 inches maximum |
| Features Provided | Finished head |
| Grip Length | 0.565 inches minimum and 0.625 inches maximum |
| Hardness Rating | 24.0 rockwell c minimum and 35.0 rockwell c maximum |
| Head Height | 0.290 inches minimum and 0.310 inches maximum |
| Head Style | Double hexagon w/hole |
| Length | 1 3/8 |
| Material | Iron |
| 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 | 0.720 inches minimum and 0.740 inches maximum |
| Thread Qty | 28 |
| Thread Qty Per Inch (tpi) | 28 |
| Thread Series Designator | UNJF |
| Thread Size | 1/4 |
| Width Between Flats | 0.311 inches minimum and 0.313 inches maximum |
Cross-reference
No interchangeable or dimensionally similar parts are on record for MS9557-20. Try the cross-reference lookup to search by a different part number.
Catalog data updated 2026-07-05. Report a data error