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BACB30LU403 — SCREW,CLOSE TOLERANCE

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

BACB30LU403: SCREW,CLOSE TOLERANCE.

The SCREW,CLOSE TOLERANCE is a the manufacturer industrial component. Key specifications include material: STEEL COMP E4340 OR STEEL COMP 4340 OR STEEL COMP 8740 OVERALL, head_style: FLAT COUNTERSUNK, grip_length: 0.178 INCHES MINIMUM AND 0.198 INCHES MAXIMUM IN, thread_class: 3A A, grip_diameter: 0.2485 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN, head_diameter: 0.455 INCHES MINIMUM AND 0.510 INCHES MAXIMUM IN. This part is cataloged in the U.S.

Government catalog under NSN 5305-01-021-3759, indicating validated use in U.S. government and defense logistics supply chains. Available through authorized enterprise resellers and TPM (Third Party Maintenance) channels.

Verify compatibility with your specific system configuration before ordering.

WHERE IT FITS
BACB30LU403
NSN: 5305-01-021-3759
FSC: 5305 — Screws
CAGE: 06725 — SPS TECHNOLOGIES, LLC DBA AIR INDUSTRIES COMPANY DIV AIR INDUSTRIES COMPANY (USA)
SPECIFICATIONS
materialSTEEL COMP E4340 OR STEEL COMP 4340 OR STEEL COMP 8740 OVERALL
head_styleFLAT COUNTERSUNK
grip_length0.178 INCHES MINIMUM AND 0.198 INCHES MAXIMUM IN
thread_class3A A
grip_diameter0.2485 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN
head_diameter0.455 INCHES MINIMUM AND 0.510 INCHES MAXIMUM IN
thread_length0.400 INCHES MINIMUM AND 0.450 INCHES MAXIMUM IN
surface_finish32.0 MICROINCHES GRIP
fastener_length0.598 INCHES MINIMUM AND 0.628 INCHES MAXIMUM IN
thread_directionRIGHT-HAND
countersink_angle100.0 DEGREES NOMINAL
surface_treatmentCADMIUM AND CHROMATE OVERALL
NSN5305-01-021-3759
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: BACB30LU403 · OEM ⚠ VERIFY BEFORE ORDERING Verify thread pitch before ordering — metric (M8×1.25) ≠ imperial (5/16-18). Wrong thread = wrong part. Grade/class stamped on bolt head determines tensile strength ✓ BROKER TIP Grade/class stamped on head determines tensile strength. Grade 8 > Grade 5 > Grade 2. Always confirm head marking matches specification requirement PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
SURFACE FINISH: 32.0 MICROINCHES THREADS
•
FASTENER LENGTH: 0.598 INCHES MINIMUM AND 0.628 INCHES MAXIMUM IN
•
SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: QQ-P-416,TY 2,CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
•
THREAD LENGTH: 0.400 INCHES MINIMUM AND 0.450 INCHES MAXIMUM IN
•
NOMINAL THREAD DIAMETER: 0.250 INCHES IN
•
HEAD STYLE: FLAT COUNTERSUNK
•
THREAD DIRECTION: RIGHT-HAND
TECHNICAL CHARACTERISTICS
SURFACE FINISH32.0 MICROINCHES THREADS
SURFACE FINISH32.0 MICROINCHES GRIP
FASTENER LENGTH0.598 INCHES MINIMUM AND 0.628 INCHES MAXIMUM IN
SURFACE TREATMENT DOCUMENT AND CLASSIFICATIONQQ-P-416,TY 2,CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
THREAD LENGTH0.400 INCHES MINIMUM AND 0.450 INCHES MAXIMUM IN
NOMINAL THREAD DIAMETER0.250 INCHES IN
HEAD STYLEFLAT COUNTERSUNK
THREAD DIRECTIONRIGHT-HAND
GRIP LENGTH0.178 INCHES MINIMUM AND 0.198 INCHES MAXIMUM IN
GRIP DIAMETER0.2485 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN
OTHER ITEMS IN FSC 5305 — Screws
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5305-00-000-0094 5305-00-000-1397 5305-00-000-2625 5305-00-000-3669 5305-00-000-3830 5305-00-000-3831
SUBSTITUTES & CROSS-REFERENCES 1
BACB30LU4-3Reference document
Same NSN cross-reference
Reference document — Secondary reference
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Insurance item — stocked against contingency demandNo demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is BACB30LU403?
BACB30LU403 is a SCREW,CLOSE TOLERANCE.
What parts can replace BACB30LU403?
There is 1 known substitute for BACB30LU403: BACB30LU4-3. Substitute compatibility should be verified for your specific system.
What is the NSN for BACB30LU403?
BACB30LU403 is cataloged in the U.S. Government catalog under NSN 5305-01-021-3759. This indicates validated use in U.S. government and defense supply chains.
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✓ PartsTable — the parts reference. Every fact cited to its source.
PartsTable Design LLC · partstable.com
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.
PartsTable commercial catalog: edition Unified commercial catalog snapshot through 2026-09-28, edition date not on file, retrieved 2026-09-28.