The Bolt,close Tolerance, cataloged under National Stock Number 5306-00-144-3971, is classified within Federal Supply Class 5306 (Bolts) of the Hardware and Abrasives group. Government technical data includes 19 specifications, cited from the U.S. Government catalog. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5306-00-144-3971 |
| Item Name | Bolt,close Tolerance |
| FSC / FSG | 5306 / 53 — Bolts |
| Status | ACTIVE |
| Head Height | 0.296 INCHES MINIMUM AND 0.328 INCHES MAXIMUM IN |
| Fastener Length | 2.141 INCHES MINIMUM AND 2.188 INCHES MAXIMUM IN |
| Surface Treatment Document and Classification | QQ-P-416 TY 2 CL 3 FED SPEC ALL TREATMENT RESPONSES OVERALL |
| Thread Length | 0.875 INCHES MINIMUM AND 0.954 INCHES MAXIMUM IN |
| Hardness Rating | 26.0 ROCKWELL C MINIMUM AND 32.0 ROCKWELL C MAXIMUM OVERALL |
| Shank Unthreaded Hole Diameter | 0.141 INCHES MINIMUM AND 0.151 INCHES MAXIMUM FIRST HOLE IN |
| Nominal Thread Diameter | 0.562 INCHES IN |
| Head Style | HEXAGON |
| Thread Direction | RIGHT-HAND |
| Grip Length | 1.234 INCHES MINIMUM AND 1.266 INCHES MAXIMUM IN |
| Width Between Flats | 0.865 INCHES MINIMUM AND 0.877 INCHES MAXIMUM IN |
| Grip Diameter | 0.5611 INCHES MINIMUM AND 0.5616 INCHES MAXIMUM IN |
| Surface Treatment | CADMIUM AND CHROMATE OVERALL |
| Minimum Tensile Strength | 125000 POUNDS PER SQUARE INCH LBS |
| Thread Class | 3A A |
| Thread Quantity Per Inch | 18 |
| Material | STEEL COMP 4140 OR STEEL COMP 8740 OR STEEL COMP 8630 OR STEEL COMP 8735 OR STEEL COMP 4130 OR STEEL COMP 4037 OVERALL |
| Thread Series Designator | UNF |
| Distance From Head Largest Bearing Surface to Shank Hole Center | 1.891 INCHES MINIMUM AND 1.922 INCHES MAXIMUM FIRST HOLE IN |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Reference | Meaning |
|---|---|
| B6812 | 4/1 Identification reference U.S. Government activity |
| AN179-20 | 2/2 Government specification standardization U.S. Government activity |
NSN 5306-00-144-3971 is a Bolt,close Tolerance, classified under FSC 5306, Bolts. Status: active.
Key specifications for 5306-00-144-3971: Head Height: 0.296 INCHES MINIMUM AND 0.328 INCHES MAXIMUM IN; Fastener Length: 2.141 INCHES MINIMUM AND 2.188 INCHES MAXIMUM IN; Surface Treatment Document and Classification: QQ-P-416 TY 2 CL 3 FED SPEC ALL TREATMENT RESPONSES OVERALL; Thread Length: 0.875 INCHES MINIMUM AND 0.954 INCHES MAXIMUM IN. 19 specifications are documented in the U.S. Government catalog.
No hazard code in the DLA record (HMIC N). Hazard information on this page is shown exactly as it appears in the DLA record.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-16.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.