The Screw,close Tolerance, cataloged under National Stock Number 5305-01-591-2238, is classified within Federal Supply Class 5305 (Screws) of the Hardware and Abrasives group. The manufacturer of record is Huck International, Inc. Government technical data includes 18 specifications, cited from the U.S. Government catalog. The record lists 15 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through both NSN and commercial part number lookups. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog.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 | 5305-01-591-2238 |
| Primary Part Number | HT4027-6-27 |
| Item Name | Screw,close Tolerance |
| FSC / FSG | 5305 / 53 — Screws |
| Manufacturer | Huck International, Inc |
| Status | ACTIVE |
| Head Height | 0.018 INCHES MAXIMUM IN |
| Fastener Length | 2.314 INCHES MINIMUM AND 2.344 INCHES MAXIMUM IN |
| Surface Treatment Document and Classification | AMS 2700 ASSN STD SINGLE TREATMENT RESPONSE OVERALL |
| Thread Length | 0.641 INCHES NOMINAL IN |
| Material Document and Classification | AMS 5662 ASSN STD SINGLE MATERIAL RESPONSE OVERALL |
| Nominal Thread Diameter | 0.375 INCHES IN |
| Head Style | FILLISTER COUNTERSUNK |
| Thread Direction | RIGHT-HAND |
| Grip Length | 1.678 INCHES MINIMUM AND 1.698 INCHES MAXIMUM IN |
| Grip Diameter | 0.374 INCHES MINIMUM AND 0.375 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 | 24 |
| Material | NICKEL ALLOY 718 OVERALL |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) |
| Head Diameter | 0.510 INCHES MINIMUM AND 0.564 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 |
|---|---|
| ST3M557-6-27 | Houston Precision Fasteners I Lp (USA) |
| HT4027-6-27 | Sps Technologies Llc Dba PB Fasteners Div PB Fasteners (USA) |
| HT4027-6-27 | Sps Technologies, Llc Dba PB Fasteners (USA) |
| ST3M557-6-27 | Valley-Todeco, Inc. Dba Arconic Fastening Systems (USA) |
| 11923-6-27 | Reid Products Inc. Dba Reid Products Inc (USA) |
| HT4027-6-27 | Howmet Global Fastening Systems Inc (USA) |
| HT4027-6-27 | Hi-Shear Corporation (USA) |
| ST3M557-6-27 | Linread Ltd (GBR) |
| HT4027-6-27 PRIMARY | Huck International, Inc (USA) |
| ST3M557-6-27 | Camcar Llc Div Camcar Llc (USA) |
| HT4027-6-27 PRIMARY | Sps Technologies, Llc Dba Air Industries Company Div Air Industries Company (USA) |
| ST3M557-6-27 | Heartland Precision Fasteners Inc (USA) |
| WC4027-6-27 PRIMARY | West Coast Aerospace, Inc. (USA) |
| ST3M557-6-27 | Saturn Fasteners Inc (USA) |
| HT4027-6-27 | Lisi Aerospace Canada Corp Div Hi Shear Holdings Inc (CAN) |
| Reference | Meaning |
|---|---|
| ST3M557-6-27 | 7/2 Vendor item drawing reference The Boeing Company Div Defense |
| HT4027-6-27 | 5/2 Secondary reference U.S. Government activity |
| HT4027-6-27 | 5/2 Secondary reference U.S. Government activity |
NSN 5305-01-591-2238 is a Screw,close Tolerance, manufactured by Huck International, Inc, classified under FSC 5305, Screws. Status: active.
NSN 5305-01-591-2238 has 15 manufacturer part numbers on file: ST3M557-6-27 (Houston Precision Fasteners I Lp), HT4027-6-27 (Sps Technologies Llc Dba PB Fasteners Div PB Fasteners), HT4027-6-27 (Sps Technologies, Llc Dba PB Fasteners), ST3M557-6-27 (Valley-Todeco, Inc. Dba Arconic Fastening Systems), 11923-6-27 (Reid Products Inc. Dba Reid Products Inc) and 10 more.
Key specifications for HT4027-6-27: Head Height: 0.018 INCHES MAXIMUM IN; Fastener Length: 2.314 INCHES MINIMUM AND 2.344 INCHES MAXIMUM IN; Surface Treatment Document and Classification: AMS 2700 ASSN STD SINGLE TREATMENT RESPONSE OVERALL; Thread Length: 0.641 INCHES NOMINAL IN. 18 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.