The Screw,close Tolerance, cataloged under National Stock Number 5305-01-591-0047, is classified within Federal Supply Class 5305 (Screws) of the Hardware and Abrasives group. The manufacturer of record is Howmet Global Fastening Systems Inc. Government technical data includes 21 specifications, cited from the U.S. Government catalog. The record lists 16 manufacturer part numbers 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through both NSN and commercial part number lookups. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog.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 | 5305-01-591-0047 |
| Primary Part Number | HT4027-4-21 |
| Item Name | Screw,close Tolerance |
| FSC / FSG | 5305 / 53 — Screws |
| Manufacturer | Howmet Global Fastening Systems Inc |
| Status | ACTIVE |
| Head Height | 0.015 INCHES MAXIMUM IN |
| Point Length | 0.045 INCHES NOMINAL IN |
| Fastener Length | 1.767 INCHES MINIMUM AND 1.797 INCHES MAXIMUM IN |
| Surface Treatment Document and Classification | AMS 2700, METHOD 1 ASSN STD SINGLE TREATMENT RESPONSE OVERALL |
| Thread Length | 0.469 INCHES NOMINAL IN |
| Material Document and Classification | AMS 5662 ASSN STD SINGLE MATERIAL RESPONSE OVERALL |
| Point Chamfer Angle | 45.0 DEGREES NOMINAL |
| Nominal Thread Diameter | 0.250 INCHES IN |
| Head Style | FILLISTER COUNTERSUNK |
| Thread Direction | RIGHT-HAND |
| Point Style | FLAT |
| Grip Length | 1.313 INCHES NOMINAL IN |
| Grip Diameter | 0.249 INCHES MINIMUM AND 0.250 INCHES MAXIMUM IN |
| Surface Treatment | PASSIVATE OVERALL |
| 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 | NICKEL ALLOY 718 OVERALL |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) |
| 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 |
|---|---|
| WC4027-4-21 | West Coast Aerospace, Inc. (USA) |
| ST3M557-4-21 | Heartland Precision Fasteners Inc (USA) |
| ST3M557-4-21 | Linread Ltd (GBR) |
| 11923-4-21 | Reid Products Inc. Dba Reid Products Inc (USA) |
| ST3M557-4-21 | Saturn Fasteners Inc (USA) |
| ST3M668-4-21 | Camcar Llc Div Camcar Llc (USA) |
| ST3M557-4-21 | Houston Precision Fasteners I Lp (USA) |
| ST3M557-4-21 | Fastener Innovation Technology, Inc. Dba F I T (USA) |
| HT4027-4-21 PRIMARY | Howmet Global Fastening Systems Inc (USA) |
| HT4027-4-21 | Sps Technologies Llc Dba PB Fasteners Div PB Fasteners (USA) |
| HT4027-4-21 PRIMARY | Sps Technologies, Llc Dba Air Industries Company Div Air Industries Company (USA) |
| HT4027-4-21 | Lisi Aerospace Canada Corp Div Hi Shear Holdings Inc (CAN) |
| HT4027-4-21 | Sps Technologies, Llc Dba PB Fasteners (USA) |
| HT4027-4-21 PRIMARY | Huck International, Inc (USA) |
| HT4027-4-21 | Hi-Shear Corporation (USA) |
| ST3M557-421 | Valley-Todeco, Inc. Dba Arconic Fastening Systems (USA) |
| Reference | Meaning |
|---|---|
| HT4027-4-21 | 5/2 Secondary reference U.S. Government activity |
| ST3M557-4-21 | 7/2 Vendor item drawing reference The Boeing Company Div Defense |
| HT4027-4-21 | 5/2 Secondary reference U.S. Government activity |
NSN 5305-01-591-0047 is a Screw,close Tolerance, manufactured by Howmet Global Fastening Systems Inc, classified under FSC 5305, Screws. Status: active.
NSN 5305-01-591-0047 has 16 manufacturer part numbers on file: WC4027-4-21 (West Coast Aerospace, Inc.), ST3M557-4-21 (Heartland Precision Fasteners Inc), ST3M557-4-21 (Linread Ltd), 11923-4-21 (Reid Products Inc. Dba Reid Products Inc), ST3M557-4-21 (Saturn Fasteners Inc) and 11 more.
Key specifications for HT4027-4-21: Head Height: 0.015 INCHES MAXIMUM IN; Point Length: 0.045 INCHES NOMINAL IN; Fastener Length: 1.767 INCHES MINIMUM AND 1.797 INCHES MAXIMUM IN; Surface Treatment Document and Classification: AMS 2700, METHOD 1 ASSN STD SINGLE TREATMENT RESPONSE OVERALL. 21 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.