The Screw,cap,socket Head, cataloged under National Stock Number 5305-01-255-3590, is classified within Federal Supply Class 5305 (Screws) of the Hardware and Abrasives group. The manufacturer of record is The Boeing Company Div Defense. Government technical data includes 16 specifications, cited from the U.S. Government catalog. The record lists 1 manufacturer part number for this item, enabling identification through both NSN and commercial part number lookups. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5305-01-255-3590 |
| Primary Part Number | 3M991-4-7 |
| Item Name | Screw,cap,socket Head |
| FSC / FSG | 5305 / 53 — Screws |
| Manufacturer | The Boeing Company Div Defense |
| Status | ACTIVE |
| Width Across Flats | 0.188 INCHES MINIMUM AND 0.190 INCHES MAXIMUM IN |
| Head Height | 0.244 INCHES MINIMUM AND 0.250 INCHES MAXIMUM IN |
| Fastener Length | 0.838 INCHES MINIMUM AND 0.888 INCHES MAXIMUM IN |
| Surface Treatment Document and Classification | QQ-P-416 TY 2 CL 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL |
| Thread Length | 0.390 INCHES MINIMUM AND 0.460 INCHES MAXIMUM IN |
| Hardness Rating | 38.0 ROCKWELL C MINIMUM AND 45.0 ROCKWELL C MAXIMUM OVERALL |
| Nominal Thread Diameter | 0.250 INCHES IN |
| Head Style | FLAT CHAMFER |
| Thread Direction | RIGHT-HAND |
| Surface Treatment | CADMIUM AND CHROMATE OVERALL |
| Internal Drive Style | HEXAGON |
| Thread Class | 3A A |
| Thread Quantity Per Inch | 28 |
| Material | STEEL OVERALL |
| Thread Series Designator | UNF |
| Head Diameter | 0.365 INCHES MINIMUM AND 0.375 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 |
|---|---|
| 3M991-4-7 PRIMARY | The Boeing Company Div Defense (USA) |
| Reference | Meaning |
|---|---|
| 3M991-4-7 | C/1 Advisory reference — outside the item-of-supply concept U.S. Government activity |
| 3M991-4-7 | 5/9 Secondary reference Usm Corp Sub of Emhart Industries Inc Parker-Kalon Fastener Div |
| 3M991-4-7 | C/1 Advisory reference — outside the item-of-supply concept Sps Technologies, Llc Dba PB Fasteners |
NSN 5305-01-255-3590 is a Screw,cap,socket Head, manufactured by The Boeing Company Div Defense, classified under FSC 5305, Screws. Status: active.
NSN 5305-01-255-3590 has 1 manufacturer part number on file: 3M991-4-7 (The Boeing Company Div Defense).
Key specifications for 3M991-4-7: Width Across Flats: 0.188 INCHES MINIMUM AND 0.190 INCHES MAXIMUM IN; Head Height: 0.244 INCHES MINIMUM AND 0.250 INCHES MAXIMUM IN; Fastener Length: 0.838 INCHES MINIMUM AND 0.888 INCHES MAXIMUM IN; Surface Treatment Document and Classification: QQ-P-416 TY 2 CL 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL. 16 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.