The Screw,close Tolerance, cataloged under National Stock Number 5305-00-409-3240, 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 21 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through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5305-00-409-3240 |
| Primary Part Number | BACB30LU8-31 |
| Item Name | Screw,close Tolerance |
| FSC / FSG | 5305 / 53 — Screws |
| Manufacturer | Howmet Global Fastening Systems Inc |
| Status | ACTIVE |
| Surface Finish | 63.0 MICROINCHES GRIP |
| Fastener Length | 2.437 INCHES MINIMUM AND 2.469 INCHES MAXIMUM IN |
| Surface Treatment Document and Classification | QQ-P-416 TY 2 CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL |
| Thread Length | 0.489 INCHES MINIMUM AND 0.541 INCHES MAXIMUM IN |
| Hardness Rating | 36.0 ROCKWELL C MINIMUM AND 40.0 ROCKWELL C MAXIMUM OVERALL |
| Material Document and Classification | MIL-S-5626 MIL SPEC 1ST MATERIAL RESPONSE OR MIL-S-5000 MIL SPEC 2ND MATERIAL RESPONSE OR MIL-S-8503 MIL SPEC 3RD MATERIAL RESPONSE OR MIL-S-6098 MIL SPEC 4TH MATERIAL RESPONSE OR MIL-S-6049 MIL SPEC 5TH MATERIAL RESPONSE OR AMS 6300 ASSN STD 6TH MATERIAL RESPONSE OVERALL |
| Nominal Thread Diameter | 0.500 INCHES IN |
| Head Style | FLAT COUNTERSUNK |
| Thread Direction | RIGHT-HAND |
| Specification/standard Data | 81205-BACB30AB MANUFACTURERS STANDARD |
| Grip Length | 1.928 INCHES MINIMUM AND 1.948 INCHES MAXIMUM IN |
| Grip Diameter | 0.4982 INCHES MINIMUM AND 0.4991 INCHES MAXIMUM IN |
| Surface Treatment | CADMIUM AND CHROMATE OVERALL |
| Minimum Tensile Strength | 160000 POUNDS PER SQUARE INCH LBS |
| Internal Drive Style | CROSS RECESS TYPE 1 |
| Countersink Angle | 99.0 DEGREES MINIMUM AND 101.0 DEGREES MAXIMUM |
| Thread Class | 3A A |
| Thread Quantity Per Inch | 20 |
| Material | STEEL COMP 4140 OR STEEL COMP E4340 OR STEEL COMP 6150 OR STEEL COMP 8735 OR STEEL COMP 8740 OR STEEL COMP 4037 OVERALL |
| Thread Series Designator | UNF |
| Head Diameter | 0.929 INCHES MINIMUM AND 1.024 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 |
|---|---|
| BACB30LU8-31 | Howmet Global Fastening Systems Inc (USA) |
| BACB30LU8-31 | Howmet Global Fastening Systems Inc Div City of Industry Operations (USA) |
| BACB30LU8-31 | Sps Technologies, Llc Dba Air Industries Company Div Air Industries Company (USA) |
| BACB30LU8-31 | Sps Technologies, Llc Dba PB Fasteners (USA) |
| BACB30LU8-31 | Huck International, Inc (USA) |
| BACB30LU8-31 | Federal Manufacturing Corp (USA) |
| BACB30LU8-31 | Valley-Todeco, Inc. Dba Arconic Fastening Systems (USA) |
| Reference | Meaning |
|---|---|
| BACB30LU8-31 | 3/2 Design control — primary reference U.S. Government activity |
| BACB30ABP8-35A | 5/9 Secondary reference U.S. Government activity |
NSN 5305-00-409-3240 is a Screw,close Tolerance, manufactured by Howmet Global Fastening Systems Inc, classified under FSC 5305, Screws. Status: active.
NSN 5305-00-409-3240 has 7 manufacturer part numbers on file: BACB30LU8-31 (Howmet Global Fastening Systems Inc), BACB30LU8-31 (Howmet Global Fastening Systems Inc Div City of Industry Operations), BACB30LU8-31 (Sps Technologies, Llc Dba Air Industries Company Div Air Industries Company), BACB30LU8-31 (Sps Technologies, Llc Dba PB Fasteners), BACB30LU8-31 (Huck International, Inc) and 2 more.
Key specifications for BACB30LU8-31: Surface Finish: 63.0 MICROINCHES GRIP; Fastener Length: 2.437 INCHES MINIMUM AND 2.469 INCHES MAXIMUM IN; Surface Treatment Document and Classification: QQ-P-416 TY 2 CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL; Thread Length: 0.489 INCHES MINIMUM AND 0.541 INCHES MAXIMUM IN. 21 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.