The Screw,shoulder, cataloged under National Stock Number 5305-01-568-1024, 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 14 manufacturer part numbers for this item, enabling identification through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5305-01-568-1024 |
| Primary Part Number | ST3M653C6-21A |
| Item Name | Screw,shoulder |
| FSC / FSG | 5305 / 53 — Screws |
| Manufacturer | The Boeing Company Div Defense |
| Status | ACTIVE |
| Head Height | 0.109 INCHES MINIMUM AND 0.111 INCHES MAXIMUM IN |
| Fastener Length | 1.953 INCHES NOMINAL IN |
| Shoulder Length | 1.129 INCHES MINIMUM AND 1.151 INCHES MAXIMUM FIRST SHOULDER IN |
| Shoulder Diameter | 0.389 INCHES MINIMUM AND 0.390 INCHES MAXIMUM FIRST SHOULDER IN |
| Thread Length | 0.641 INCHES NOMINAL IN |
| Shoulder Shape | ROUND FIRST SHOULDER |
| Nominal Thread Diameter | 0.375 INCHES IN |
| Head Style | FLAT COUNTERSUNK UNDERCUT |
| Thread Direction | RIGHT-HAND |
| 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 | STEEL COMP XM-13 OVERALL |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) |
| Head Diameter | 0.756 INCHES MINIMUM AND 0.760 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 |
|---|---|
| HT4020-6-21AX | Sps Technologies, Llc Dba Air Industries Company Div Air Industries Company (USA) |
| 11927C6-21A | Reid Products Inc. Dba Reid Products Inc (USA) |
| ST3M653C6-21A | Fastener Innovation Technology, Inc. Dba F I T (USA) |
| ST3M653C6-21A | Valley-Todeco, Inc. Dba Arconic Fastening Systems (USA) |
| ST3M653C6-21A PRIMARY | The Boeing Company Div Defense (USA) |
| ST3M653C6-21A | Heartland Precision Fasteners Inc (USA) |
| HT4020-6-21AX | Sps Technologies, Llc Dba PB Fasteners (USA) |
| HT4020-6-21AX | Sps Technologies Llc Dba PB Fasteners Div PB Fasteners (USA) |
| HT4020-6-21AX | Sps Technologies Ltd, Tj Brooks Division (GBR) |
| HT4020-6-21AX | Hi-Shear Corporation (USA) |
| ST3M653C6-21A | Houston Precision Fasteners I Lp (USA) |
| HT4020-6-21AX | Howmet Global Fastening Systems Inc (USA) |
| WC4020-6-21AX | West Coast Aerospace, Inc. (USA) |
| HT4020-6-21AX | Huck International, Inc (USA) |
| Reference | Meaning |
|---|---|
| HT4020-6-21AX | 5/2 Secondary reference U.S. Government activity |
| HT4020-6-21AX | 5/2 Secondary reference U.S. Government activity |
NSN 5305-01-568-1024 is a Screw,shoulder, manufactured by The Boeing Company Div Defense, classified under FSC 5305, Screws. Status: active.
NSN 5305-01-568-1024 has 14 manufacturer part numbers on file: HT4020-6-21AX (Sps Technologies, Llc Dba Air Industries Company Div Air Industries Company), 11927C6-21A (Reid Products Inc. Dba Reid Products Inc), ST3M653C6-21A (Fastener Innovation Technology, Inc. Dba F I T), ST3M653C6-21A (Valley-Todeco, Inc. Dba Arconic Fastening Systems), ST3M653C6-21A (The Boeing Company Div Defense) and 9 more.
Key specifications for ST3M653C6-21A: Head Height: 0.109 INCHES MINIMUM AND 0.111 INCHES MAXIMUM IN; Fastener Length: 1.953 INCHES NOMINAL IN; Shoulder Length: 1.129 INCHES MINIMUM AND 1.151 INCHES MAXIMUM FIRST SHOULDER IN; Shoulder Diameter: 0.389 INCHES MINIMUM AND 0.390 INCHES MAXIMUM FIRST SHOULDER IN. 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.