The Screw,close Tolerance, cataloged under National Stock Number 5305-01-203-1664, is classified within Federal Supply Class 5305 (Screws) of the Hardware and Abrasives group. The manufacturer of record is Howmet Global Fastening Systems Inc. Government technical data includes 17 specifications, cited from the U.S. Government catalog. The record lists 7 manufacturer part numbers 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through both NSN and commercial part number lookups. 5 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog.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 | 5305-01-203-1664 |
| Primary Part Number | BACB30LU4-18 |
| Item Name | Screw,close Tolerance |
| FSC / FSG | 5305 / 53 — Screws |
| Manufacturer | Howmet Global Fastening Systems Inc |
| Status | ACTIVE |
| Fastener Length | 1.540 INCHES MINIMUM AND 1.560 INCHES MAXIMUM IN |
| Surface Treatment Document and Classification | QQ-P-416 FED SPEC SINGLE TREATMENT RESPONSE OVERALL |
| Thread Length | 0.425 INCHES NOMINAL IN |
| Material Document and Classification | MIL-S-5000 MIL SPEC 1ST MATERIAL RESPONSE OR MIL-S-6049 MIL SPEC 2ND MATERIAL RESPONSE OR AMS 6322 ASSN STD 2ND MATERIAL RESPONSE OVERALL |
| Nominal Thread Diameter | 0.250 INCHES IN |
| Head Style | FLAT COUNTERSUNK |
| Thread Direction | RIGHT-HAND |
| Grip Length | 1.115 INCHES MINIMUM AND 1.135 INCHES MAXIMUM IN |
| Grip Diameter | 0.2485 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN |
| Surface Treatment | CADMIUM OVERALL |
| Internal Drive Style | CROSS RECESS TYPE 1 |
| Countersink Angle | 99.0 DEGREES MINIMUM AND 100.0 DEGREES MAXIMUM |
| Thread Class | 3A A |
| Thread Quantity Per Inch | 28 |
| Material | STEEL COMP 4340 OR STEEL COMP 8740 OVERALL |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) |
| Head Diameter | 0.455 INCHES MINIMUM AND 0.510 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 |
|---|---|
| BACB30LU4-18 PRIMARY | Howmet Global Fastening Systems Inc (USA) |
| BACB30LU4-18 PRIMARY | Baumbach E a Mfg Co (USA) |
| BACB30LU4-18 PRIMARY | Sps Technologies Llc Dba PB Fasteners Div PB Fasteners (USA) |
| BACB30LU4-18 PRIMARY | Federal Manufacturing Corp (USA) |
| BACB30LU4-18 PRIMARY | Huck International, Inc (USA) |
| BACB30LU4-18 PRIMARY | Sps Technologies, Llc Dba Air Industries Company Div Air Industries Company (USA) |
| BACB30LU4-18 | Sonic Industries, Inc. Dba Sonic Industries Inc Div Sonic Industries (USA) |
| Reference | Meaning |
|---|---|
| BACB30LU4-18 | 5/9 Secondary reference U.S. Government activity |
| BACB30LU4-18 | 5/9 Secondary reference Sps Technologies, Llc Dba PB Fasteners |
| BACB30LU4-18 | 3/2 Design control — primary reference U.S. Government activity |
| BACB30LU4-18 | 3/2 Design control — primary reference U.S. Government activity |
| BACB30LU4-18 | 3/2 Design control — primary reference U.S. Government activity |
NSN 5305-01-203-1664 is a Screw,close Tolerance, manufactured by Howmet Global Fastening Systems Inc, classified under FSC 5305, Screws. Status: active.
NSN 5305-01-203-1664 has 7 manufacturer part numbers on file: BACB30LU4-18 (Howmet Global Fastening Systems Inc), BACB30LU4-18 (Baumbach E a Mfg Co), BACB30LU4-18 (Sps Technologies Llc Dba PB Fasteners Div PB Fasteners), BACB30LU4-18 (Federal Manufacturing Corp), BACB30LU4-18 (Huck International, Inc) and 2 more.
Key specifications for BACB30LU4-18: Fastener Length: 1.540 INCHES MINIMUM AND 1.560 INCHES MAXIMUM IN; Surface Treatment Document and Classification: QQ-P-416 FED SPEC SINGLE TREATMENT RESPONSE OVERALL; Thread Length: 0.425 INCHES NOMINAL IN; Material Document and Classification: MIL-S-5000 MIL SPEC 1ST MATERIAL RESPONSE OR MIL-S-6049 MIL SPEC 2ND MATERIAL RESPONSE OR AMS 6322 ASSN STD 2ND MATERIAL RESPONSE OVERALL. 17 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.