The Screw,close Tolerance, cataloged under National Stock Number 5305-01-027-5251, is classified within Federal Supply Class 5305 (Screws) of the Hardware and Abrasives group. The manufacturer of record is Hi-Shear Corporation. Government technical data includes 20 specifications, cited from the U.S. Government catalog. The record lists 4 manufacturer part numbers for this item, enabling identification through both NSN and commercial part number lookups. 4 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5305-01-027-5251 |
| Primary Part Number | HT239PB4-9 |
| Item Name | Screw,close Tolerance |
| FSC / FSG | 5305 / 53 — Screws |
| Manufacturer | Hi-Shear Corporation |
| Status | ACTIVE |
| Surface Finish | 63.0 MICROINCHES GRIP |
| Surface Finish | 63.0 MICROINCHES THREADS |
| Fastener Length | 0.862 INCHES MINIMUM AND 0.909 INCHES MAXIMUM IN |
| Surface Treatment Document and Classification | QQ-P-416,TY 2,CL 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL |
| Thread Length | 0.290 INCHES MINIMUM AND 0.357 INCHES MAXIMUM IN |
| Nominal Thread Diameter | 0.250 INCHES IN |
| Head Style | FLAT COUNTERSUNK |
| Thread Direction | RIGHT-HAND |
| Specification/standard Data | 26512-GB510L MANUFACTURERS STANDARD |
| Grip Length | 0.552 INCHES MINIMUM AND 0.572 INCHES MAXIMUM IN |
| Grip Diameter | 0.2485 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN |
| Surface Treatment | CADMIUM AND CHROMATE OVERALL |
| Minimum Tensile Strength | 160000 POUNDS PER SQUARE INCH LBS |
| Internal Drive Style | HIGH-TORQUE |
| Countersink Angle | 100.0 DEGREES NOMINAL |
| Thread Class | 3A A |
| Thread Quantity Per Inch | 28 |
| Material | STEEL COMP 4140 OR STEEL COMP E4340 OR STEEL COMP 6150 OR STEEL COMP 8735 OR STEEL COMP 8740 OVERALL |
| Thread Series Designator | UNF |
| Head Diameter | 0.390 INCHES MINIMUM AND 0.395 INCHES MAXIMUM IN |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Part Number | Manufacturer |
|---|---|
| HT239PB4-9 PRIMARY | Hi-Shear Corporation (USA) |
| HT239PB4-9 PRIMARY | Lisi Aerospace Canada Corp Div Hi Shear Holdings Inc (CAN) |
| HT8043-4-9 PRIMARY | Howmet Global Fastening Systems Inc (USA) |
| HT239PB-4-9 | Leonardo Spa Aeronautics Division - Pomigliano D'arco Site (ITA) |
| Reference | Meaning |
|---|---|
| 106750-4-9 | 3/2 Design control — primary reference U.S. Government activity |
| HT8043-4-9 | 5/9 Secondary reference U.S. Government activity |
| GB510L4-9 | 7/2 Vendor item drawing reference Northrop Grumman Systems Corporation |
| GB510L4-9 | 5/2 Secondary reference U.S. Government activity |
NSN 5305-01-027-5251 is a Screw,close Tolerance, manufactured by Hi-Shear Corporation, classified under FSC 5305, Screws. Status: active.
NSN 5305-01-027-5251 has 4 manufacturer part numbers on file: HT239PB4-9 (Hi-Shear Corporation), HT239PB4-9 (Lisi Aerospace Canada Corp Div Hi Shear Holdings Inc), HT8043-4-9 (Howmet Global Fastening Systems Inc), HT239PB-4-9 (Leonardo Spa Aeronautics Division - Pomigliano D'arco Site).
Key specifications for HT239PB4-9: Surface Finish: 63.0 MICROINCHES GRIP; Surface Finish: 63.0 MICROINCHES THREADS; Fastener Length: 0.862 INCHES MINIMUM AND 0.909 INCHES MAXIMUM IN; Surface Treatment Document and Classification: QQ-P-416,TY 2,CL 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL. 20 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.