The Washer,key, cataloged under National Stock Number 5310-00-920-5440, is classified within Federal Supply Class 5310 (Nuts and Washers) of the Hardware and Abrasives group. The manufacturer of record is Mcmellon Bros., Incorporated Dba Mc Mellon Brothers Inc. Government technical data includes 12 specifications, cited from the U.S. Government catalog. The record lists 1 manufacturer part number for this item, enabling identification through both NSN and commercial part number lookups. 5 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5310-00-920-5440 |
| Primary Part Number | BACW10BW20 |
| Item Name | Washer,key |
| FSC / FSG | 5310 / 53 — Nuts and Washers |
| Manufacturer | Mcmellon Bros., Incorporated Dba Mc Mellon Brothers Inc |
| Status | ACTIVE |
| Internal Straight Key Width | 0.290 INCHES MINIMUM AND 0.300 INCHES MAXIMUM IN |
| Distance From Centerline to Top of Internal Key | 1.090 INCHES MINIMUM AND 1.110 INCHES MAXIMUM IN |
| Overall Distance Including Keys | 3.500 INCHES MINIMUM AND 3.580 INCHES MAXIMUM IN |
| Style Designator | KEY |
| Material Document and Classification | MIL-S-18729 MIL SPEC SINGLE MATERIAL RESPONSE OVERALL |
| Outside Diameter | 3.240 INCHES MINIMUM AND 3.260 INCHES MAXIMUM IN |
| Material Thickness | 0.046 INCHES MINIMUM AND 0.054 INCHES MAXIMUM IN |
| External Straight Key Width | 0.150 INCHES MINIMUM AND 0.170 INCHES MAXIMUM IN |
| External Key Quantity | 4 |
| Material | STEEL OVERALL |
| Internal Key Quantity | 2 |
| Hole Diameter | 2.610 INCHES MINIMUM AND 2.630 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 |
|---|---|
| BACW10BW20 | Mcmellon Bros., Incorporated Dba Mc Mellon Brothers Inc (USA) |
| Reference | Meaning |
|---|---|
| BACW10BW20 | 5/9 Secondary reference Standard Locknut, L.l.c. |
| BACW10BW20 | 3/2 Design control — primary reference U.S. Government activity |
| 114D6095-1 | 5/9 Secondary reference The Boeing Company |
| 114D6095-1 | 5/2 Secondary reference U.S. Government activity |
| BACW10BW20 | C/1 Advisory reference — outside the item-of-supply concept The Boeing Company |
NSN 5310-00-920-5440 is a Washer,key, manufactured by Mcmellon Bros., Incorporated Dba Mc Mellon Brothers Inc, classified under FSC 5310, Nuts and Washers. Status: active.
NSN 5310-00-920-5440 has 1 manufacturer part number on file: BACW10BW20 (Mcmellon Bros., Incorporated Dba Mc Mellon Brothers Inc).
Key specifications for BACW10BW20: Internal Straight Key Width: 0.290 INCHES MINIMUM AND 0.300 INCHES MAXIMUM IN; Distance From Centerline to Top of Internal Key: 1.090 INCHES MINIMUM AND 1.110 INCHES MAXIMUM IN; Overall Distance Including Keys: 3.500 INCHES MINIMUM AND 3.580 INCHES MAXIMUM IN; Style Designator: KEY. 12 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.