The Washer,flat, cataloged under National Stock Number 5310-01-657-3721, is classified within Federal Supply Class 5310 (Nuts and Washers) of the Hardware and Abrasives group. The manufacturer of record is U S Army Tank Automotive Command Amsta-Im-Mm. Government technical data includes 10 specifications, cited from the U.S. Government catalog. The record lists 2 manufacturer part numbers for this item, enabling identification through both NSN and commercial part number lookups. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5310-01-657-3721 |
| Primary Part Number | 12641078-001 |
| Item Name | Washer,flat |
| FSC / FSG | 5310 / 53 — Nuts and Washers |
| Manufacturer | U S Army Tank Automotive Command Amsta-Im-Mm |
| Status | ACTIVE |
| Overall Diameter | 2.22 INCHES MINIMUM AND 2.28 INCHES MAXIMUM IN |
| Hardness Rating | 38.0 ROCKWELL C MINIMUM AND 42.0 ROCKWELL C MAXIMUM |
| Cross-Sectional Shape Style | RECTANGULAR |
| Color | BLACK OVERALL |
| Surface Treatment | PHOSPHATE AND ZINC OVERALL |
| Peripheral Shape Style | ROUND |
| Material | STEEL OVERALL |
| Center Hole Shape Style | ROUND |
| Hole Diameter | 1.385 INCHES MINIMUM AND 1.425 INCHES MAXIMUM IN |
| Thickness | 0.168 INCHES MINIMUM AND 0.208 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 |
|---|---|
| 12641078-001 PRIMARY | U S Army Tank Automotive Command Amsta-Im-Mm (USA) |
| 4239600 PRIMARY | Oshkosh Defense Llc (USA) |
NSN 5310-01-657-3721 is a Washer,flat, manufactured by U S Army Tank Automotive Command Amsta-Im-Mm, classified under FSC 5310, Nuts and Washers. Status: active.
NSN 5310-01-657-3721 has 2 manufacturer part numbers on file: 12641078-001 (U S Army Tank Automotive Command Amsta-Im-Mm), 4239600 (Oshkosh Defense Llc).
Key specifications for 12641078-001: Overall Diameter: 2.22 INCHES MINIMUM AND 2.28 INCHES MAXIMUM IN; Hardness Rating: 38.0 ROCKWELL C MINIMUM AND 42.0 ROCKWELL C MAXIMUM; Cross-Sectional Shape Style: RECTANGULAR; Color: BLACK OVERALL. 10 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.