The Screw,cap,socket Head, cataloged under National Stock Number 5305-01-443-4454, is classified within Federal Supply Class 5305 (Screws) of the Hardware and Abrasives group. The manufacturer of record is Naval Sea Systems Command. Government technical data includes 19 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through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. 1 item shares a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5305-01-443-4454 |
| Primary Part Number | 556-6406600-MVSA-A21 |
| Item Name | Screw,cap,socket Head |
| FSC / FSG | 5305 / 53 — Screws |
| Manufacturer | Naval Sea Systems Command |
| Status | ACTIVE |
| Width Across Flats | 0.156 INCHES NOMINAL IN |
| Head Height | 0.185 INCHES MINIMUM AND 0.190 INCHES MAXIMUM IN |
| Fastener Length | 0.625 INCHES NOMINAL IN |
| Thread Length | 0.542 INCHES MINIMUM AND 0.625 INCHES MAXIMUM IN |
| Hardness Rating | 28.0 ROCKWELL C MINIMUM AND 38.0 ROCKWELL C MAXIMUM FASTENER |
| Material Document and Classification | ASTM F594 ASSN STD SINGLE MATERIAL RESPONSE FASTENER |
| Nominal Thread Diameter | 0.190 INCHES IN |
| Head Style | FLAT CHAMFER |
| Thread Direction | RIGHT-HAND |
| Locking Feature | PATCH OR PELLET OR STRIP THREADS |
| Minimum Tensile Strength | 135000 POUNDS PER SQUARE INCH LBS |
| Minimum Yield Strength | 105000 POUNDS PER SQUARE INCH LBS |
| Internal Drive Style | HEXAGON |
| Thread Class | 2A A |
| Thread Quantity Per Inch | 24 |
| Material | PLASTIC POLYAMIDE NYLON LOCKING FEATURE |
| Material | STEEL COMP 630 FASTENER |
| Thread Series Designator | UNIFIED NATIONAL COARSE (UNC) |
| Head Diameter | 0.303 INCHES MINIMUM AND 0.312 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 |
|---|---|
| 556-6406600-MVSA-B21 | Naval Sea Systems Command (USA) |
| 556-6406600-MVSA-A21 PRIMARY | Naval Sea Systems Command (USA) |
| Reference | Meaning |
|---|---|
| 218013241 | C/1 Advisory reference — outside the item-of-supply concept Naval Sea Systems Command |
NSN 5305-01-443-4454 is a Screw,cap,socket Head, manufactured by Naval Sea Systems Command, classified under FSC 5305, Screws. Status: active.
NSN 5305-01-443-4454 has 2 manufacturer part numbers on file: 556-6406600-MVSA-B21 (Naval Sea Systems Command), 556-6406600-MVSA-A21 (Naval Sea Systems Command).
1 possible match (shared part number, not a government interchangeability claim): 5305-01-541-2633. Verify interchangeability with system specifications before substitution.
Key specifications for 556-6406600-MVSA-A21: Width Across Flats: 0.156 INCHES NOMINAL IN; Head Height: 0.185 INCHES MINIMUM AND 0.190 INCHES MAXIMUM IN; Fastener Length: 0.625 INCHES NOMINAL IN; Thread Length: 0.542 INCHES MINIMUM AND 0.625 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.