The Washer,concave, cataloged under National Stock Number 5310-01-434-5879, is classified within Federal Supply Class 5310 (Nuts and Washers) of the Hardware and Abrasives group. The manufacturer of record is Howmet Global Fastening Systems Inc. Government technical data includes 13 specifications, cited from the U.S. Government catalog. The record lists 3 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through both NSN and commercial part number lookups. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 1 item shares a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5310-01-434-5879 |
| Primary Part Number | BACW10AU4 |
| Item Name | Washer,concave |
| FSC / FSG | 5310 / 53 — Nuts and Washers |
| Manufacturer | Howmet Global Fastening Systems Inc |
| Status | ACTIVE |
| Surface Finish | 63.0 MICROINCHES COUNTERBORE WALL |
| Surface Treatment Document and Classification | QQ-P-416, TY 2, CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL |
| Radius | 0.300 INCHES MAXIMUM IN |
| Hardness Rating | 38.0 ROCKWELL C MINIMUM AND 44.0 ROCKWELL C MAXIMUM |
| Style Designator | CONCAVE |
| Material Document and Classification | MIL-S-6049 MIL SPEC 1ST MATERIAL RESPONSE OR MIL-S-6050 MIL SPEC 2ND MATERIAL RESPONSE OR MIL-S-6758 MIL SPEC 3RD MATERIAL RESPONSE OVERALL |
| Outside Diameter | 0.505 INCHES MINIMUM AND 0.515 INCHES MAXIMUM IN |
| Recess Depth | 0.051 INCHES NOMINAL IN |
| Material Thickness | 0.113 INCHES MINIMUM AND 0.123 INCHES MAXIMUM IN |
| Specification/standard Data | 81205-BACW10AU MANUFACTURERS STANDARD |
| Surface Treatment | CADMIUM AND CHROMATE OVERALL |
| Material | STEEL COMP 8740 OR STEEL COMP 8630 OR STEEL COMP 4130 OVERALL |
| Hole Diameter | 0.348 INCHES MINIMUM AND 0.354 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 |
|---|---|
| BACW10AU4 | Howmet Global Fastening Systems Inc (USA) |
| BACW10AU4 | Anillo Industries Llc (USA) |
| BACW10AU4 | Sps Technologies, Llc Dba PB Fasteners (USA) |
| Reference | Meaning |
|---|---|
| K19701P4 | 5/9 Secondary reference Howmet Global Fastening Systems Inc |
| 53488W-428 | 5/9 Secondary reference Sps Technologies, Llc Dba PB Fasteners |
| BACW10AU4 | 3/2 Design control — primary reference U.S. Government activity |
NSN 5310-01-434-5879 is a Washer,concave, manufactured by Howmet Global Fastening Systems Inc, classified under FSC 5310, Nuts and Washers. Status: active.
NSN 5310-01-434-5879 has 3 manufacturer part numbers on file: BACW10AU4 (Howmet Global Fastening Systems Inc), BACW10AU4 (Anillo Industries Llc), BACW10AU4 (Sps Technologies, Llc Dba PB Fasteners).
1 possible match (shared part number, not a government interchangeability claim): 5310-01-669-3966. Verify interchangeability with system specifications before substitution.
Key specifications for BACW10AU4: Surface Finish: 63.0 MICROINCHES COUNTERBORE WALL; Surface Treatment Document and Classification: QQ-P-416, TY 2, CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL; Radius: 0.300 INCHES MAXIMUM IN; Hardness Rating: 38.0 ROCKWELL C MINIMUM AND 44.0 ROCKWELL C MAXIMUM. 13 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.