The Screw,close Tolerance, cataloged under National Stock Number 5305-01-520-3102, 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 23 specifications, cited from the U.S. Government catalog. The record lists 2 manufacturer part numbers for this item, enabling identification through both NSN and commercial part number lookups. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5305-01-520-3102 |
| Primary Part Number | HT181-4-20 |
| Item Name | Screw,close Tolerance |
| FSC / FSG | 5305 / 53 — Screws |
| Manufacturer | Hi-Shear Corporation |
| Status | ACTIVE |
| Surface Finish | 32.0 MICROINCHES THREADS |
| Surface Finish | 32.0 MICROINCHES GRIP |
| Surface Finish | 32.0 MICROINCHES BEARING SURFACE OF HEAD |
| Point Length | 0.050 INCHES NOMINAL IN |
| Fastener Length | 1.703 INCHES MINIMUM AND 1.750 INCHES MAXIMUM IN |
| Surface Treatment Document and Classification | NAS672 ASSN STD SINGLE TREATMENT RESPONSE OVERALL |
| Thread Length | 0.469 INCHES NOMINAL IN |
| Material Document and Classification | NAS498 ASSN STD SINGLE MATERIAL RESPONSE OVERALL |
| Nominal Thread Diameter | 0.2500 INCHES IN |
| Head Style | FLAT COUNTERSUNK |
| Thread Direction | RIGHT-HAND |
| Point Style | FLAT |
| Grip Length | 1.240 INCHES MINIMUM AND 1.260 INCHES MAXIMUM IN |
| Grip Diameter | 0.2485 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN |
| Surface Treatment | CADMIUM OVERALL |
| Minimum Tensile Strength | 6400 POUNDS PER SQUARE INCH LBS |
| Internal Drive Style | HIGH-TORQUE |
| Countersink Angle | 99.0 DEGREES MINIMUM AND 101.0 DEGREES MAXIMUM |
| Thread Class | 3A A |
| Thread Quantity Per Inch | 28 |
| Material | STEEL OVERALL |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) |
| Head Diameter | 0.464 INCHES MINIMUM AND 0.507 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 |
|---|---|
| HT181-4-20 PRIMARY | Hi-Shear Corporation (USA) |
| HT181-4-20 PRIMARY | Lisi Aerospace Canada Corp Div Hi Shear Holdings Inc (CAN) |
NSN 5305-01-520-3102 is a Screw,close Tolerance, manufactured by Hi-Shear Corporation, classified under FSC 5305, Screws. Status: active.
NSN 5305-01-520-3102 has 2 manufacturer part numbers on file: HT181-4-20 (Hi-Shear Corporation), HT181-4-20 (Lisi Aerospace Canada Corp Div Hi Shear Holdings Inc).
Key specifications for HT181-4-20: Surface Finish: 32.0 MICROINCHES THREADS; Surface Finish: 32.0 MICROINCHES GRIP; Surface Finish: 32.0 MICROINCHES BEARING SURFACE OF HEAD; Point Length: 0.050 INCHES NOMINAL IN. 23 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.