The Screw,cap,socket Head, cataloged under National Stock Number 5305-01-251-3445, is classified within Federal Supply Class 5305 (Screws) of the Hardware and Abrasives group. The manufacturer of record is Mcmaster-Carr Supply Co. Government technical data includes 17 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through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5305-01-251-3445 |
| Primary Part Number | 91251A537 |
| Item Name | Screw,cap,socket Head |
| FSC / FSG | 5305 / 53 — Screws |
| Manufacturer | Mcmaster-Carr Supply Co |
| Status | ACTIVE |
| Width Across Flats | 0.188 INCHES NOMINAL IN |
| Head Height | 0.244 INCHES MINIMUM AND 0.250 INCHES MAXIMUM IN |
| Fastener Length | 0.500 INCHES NOMINAL IN |
| Thread Length | 0.400 INCHES MINIMUM AND 0.500 INCHES MAXIMUM IN |
| Hardness Rating | 39.0 ROCKWELL C MINIMUM AND 45.0 ROCKWELL C MAXIMUM OVERALL |
| Material Document and Classification | SAE GRADE 8 ASSN STD ALL MATERIAL RESPONSES OVERALL |
| Nominal Thread Diameter | 0.250 INCHES IN |
| Head Style | FLAT CHAMFER |
| Thread Direction | RIGHT-HAND |
| Surface Treatment | OXIDE OVERALL |
| Minimum Tensile Strength | 180000 POUNDS PER SQUARE INCH LBS |
| Internal Drive Style | HEXAGON |
| Thread Class | 2A A |
| Thread Quantity Per Inch | 20 |
| Material | STEEL COMP 1013 OR STEEL COMP 1015 OR STEEL COMP 1016 OR STEEL COMP 1017 OR STEEL COMP 1018 OR STEEL COMP 1019 OR STEEL COMP 1020 OR STEEL COMP 1021 OR STEEL COMP 1022 OR STEEL COMP 1023 OR STEEL COMP 1524 OR STEEL COMP 1025 OR STEEL COMP 1026 OR STEEL COMP 1527 OR STEEL COMP 1029 OR STEEL COMP 1030 OR STEEL COMP 1033 OR STEEL COMP 1034 OR STEEL COMP 1035 OR STEEL COMP 1536 OR STEEL COMP 1037 OR STEEL COMP 1038 OR STEEL COMP 1039 OR STEEL COMP 1040 OR STEEL COMP 1541 OVERALL |
| Thread Series Designator | UNIFIED NATIONAL COARSE (UNC) |
| Head Diameter | 0.375 INCHES NOMINAL 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 |
|---|---|
| 91251A537 PRIMARY | Mcmaster-Carr Supply Co (USA) |
| Reference | Meaning |
|---|---|
| 91251A537 | C/1 Advisory reference — outside the item-of-supply concept Mcmaster-Carr Supply Company |
NSN 5305-01-251-3445 is a Screw,cap,socket Head, manufactured by Mcmaster-Carr Supply Co, classified under FSC 5305, Screws. Status: active.
NSN 5305-01-251-3445 has 1 manufacturer part number on file: 91251A537 (Mcmaster-Carr Supply Co).
Key specifications for 91251A537: Width Across Flats: 0.188 INCHES NOMINAL IN; Head Height: 0.244 INCHES MINIMUM AND 0.250 INCHES MAXIMUM IN; Fastener Length: 0.500 INCHES NOMINAL IN; Thread Length: 0.400 INCHES MINIMUM AND 0.500 INCHES MAXIMUM IN. 17 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.