The Bolt,close Tolerance, cataloged under National Stock Number 5306-00-321-9217, is classified within Federal Supply Class 5306 (Bolts) of the Hardware and Abrasives group. The manufacturer of record is Heartland Precision Fasteners Inc. Government technical data includes 15 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through both NSN and commercial part number lookups. 14 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5306-00-321-9217 |
| Primary Part Number | ST3M571-4-38 |
| Item Name | Bolt,close Tolerance |
| FSC / FSG | 5306 / 53 — Bolts |
| Manufacturer | Heartland Precision Fasteners Inc |
| Status | ACTIVE |
| Extended Washer Thickness | 0.059 INCHES MINIMUM AND 0.079 INCHES MAXIMUM IN |
| Head Height | 0.290 INCHES MINIMUM AND 0.310 INCHES MAXIMUM IN |
| Fastener Length | 2.828 INCHES MINIMUM AND 2.858 INCHES MAXIMUM IN |
| Extended Washer Diameter | 0.428 INCHES MINIMUM AND 0.438 INCHES MAXIMUM IN |
| Thread Length | 0.443 INCHES MINIMUM AND 0.493 INCHES MAXIMUM IN |
| Nominal Thread Diameter | 0.250 INCHES IN |
| Head Style | DOUBLE HEXAGON W/HOLE |
| Thread Direction | RIGHT-HAND |
| Width Between Flats | 0.034 INCHES MINIMUM AND 0.313 INCHES MAXIMUM IN |
| Grip Diameter | 0.2490 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN |
| Surface Treatment | PASSIVATE OVERALL |
| Thread Class | 3A A |
| Thread Quantity Per Inch | 28 |
| Material | STEEL CORROSION RESISTING OVERALL |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) |
| 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 |
|---|---|
| ST3M571-4-38 | Heartland Precision Fasteners Inc (USA) |
| ST3M571-4-38 | Sps Technologies, Llc Dba Air Industries Company Div Air Industries Company (USA) |
| ST3M571-4-38 | Sps Technologies, Llc Dba PB Fasteners (USA) |
| ST3M571-4-38 | Houston Precision Fasteners I Lp (USA) |
| ST3M571-4-38 | Fastener Innovation Technology, Inc. Dba F I T (USA) |
| ST3M571-4-38 | Sonic Industries, Inc. Dba Sonic Industries Inc Div Sonic Industries (USA) |
| ST3M571-4-38 | Reid Products Inc. Dba Reid Products Inc (USA) |
| ST3M571-4-38 | Sps Technologies Llc Dba PB Fasteners Div PB Fasteners (USA) |
| ST3M571-4-38 | Howmet Global Fastening Systems Inc (USA) |
| ST3M571-4-38 | B & B Specialties Inc Dba Gs Aerospace Div Gs Aerospace (USA) |
| ST3M571-4-38 | Saturn Fasteners Inc (USA) |
| ST3M571-4-38 | Hi-Shear Corporation (USA) |
| ST3M571-4-38 | Space-Lok, Inc. Dba Space-Lok Inc Div Space-Lok (USA) |
| ST3M571-4-38 | Valley-Todeco, Inc. Dba Arconic Fastening Systems (USA) |
| ST3M571-4-38 | Huck International, Inc (USA) |
| Reference | Meaning |
|---|---|
| ST3M571-4-38 | 5/2 Secondary reference U.S. Government activity |
| MB84-4-38 | 5/9 Secondary reference Lisi Aerospace Canada Corp Div Hi Shear Holdings Inc |
| AIC752-4-38 | 5/9 Secondary reference Sps Technologies, Llc Dba Air Industries Company Div Air Industries Company |
| 74328-4-38 | 3/9 Design control — primary reference Sps Technologies, Llc Dba PB Fasteners |
| ST3M571-4-38 | 7/2 Vendor item drawing reference The Boeing Company Div Defense |
| S11-1059-4-38 | 5/9 Secondary reference Sonic Industries, Inc. Dba Sonic Industries Inc Div Sonic Industries |
| VAL23033-4-38 | 5/9 Secondary reference Valley-Todeco, Inc. Dba Arconic Fastening Systems |
| GS1030-4-38 | 5/9 Secondary reference B & B Specialties Inc Dba Gs Aerospace Div Gs Aerospace |
| VS3060-4-38 | 5/9 Secondary reference U.S. Government activity |
| 74328-4-38 | 5/9 Secondary reference Sps Technologies Inc |
| S371-4-38 | 5/9 Secondary reference U.S. Government activity |
| BM3326-4-38 | 5/9 Secondary reference U.S. Government activity |
| MB84-4-38 | 5/9 Secondary reference Hi-Shear Corporation |
| BM3326-4-38 | 5/9 Secondary reference Huck International, Inc |
NSN 5306-00-321-9217 is a Bolt,close Tolerance, manufactured by Heartland Precision Fasteners Inc, classified under FSC 5306, Bolts. Status: active.
NSN 5306-00-321-9217 has 15 manufacturer part numbers on file: ST3M571-4-38 (Heartland Precision Fasteners Inc), ST3M571-4-38 (Sps Technologies, Llc Dba Air Industries Company Div Air Industries Company), ST3M571-4-38 (Sps Technologies, Llc Dba PB Fasteners), ST3M571-4-38 (Houston Precision Fasteners I Lp), ST3M571-4-38 (Fastener Innovation Technology, Inc. Dba F I T) and 10 more.
Key specifications for ST3M571-4-38: Extended Washer Thickness: 0.059 INCHES MINIMUM AND 0.079 INCHES MAXIMUM IN; Head Height: 0.290 INCHES MINIMUM AND 0.310 INCHES MAXIMUM IN; Fastener Length: 2.828 INCHES MINIMUM AND 2.858 INCHES MAXIMUM IN; Extended Washer Diameter: 0.428 INCHES MINIMUM AND 0.438 INCHES MAXIMUM IN. 15 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.