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BACB30LL4-20 — SCREW,CLOSE TOLERANCE

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

BACB30LL4-20: SCREW,CLOSE TOLERANCE.

The SCREW,CLOSE TOLERANCE is a the manufacturer industrial component. Key specifications include material: IRON ALLOY 660 OVERALL, head_style: FLAT COUNTERSUNK, grip_length: 1.240 INCHES MINIMUM AND 1.260 INCHES MAXIMUM IN, thread_class: 3A A, grip_diameter: 0.2485 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN, head_diameter: 0.354 INCHES MINIMUM AND 0.399 INCHES MAXIMUM IN. This part is cataloged in the U.S.

Government catalog under NSN 5305-01-049-5665, 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
BACB30LL4-20
NSN: 5305-01-049-5665
FSC: 5305 — Screws
CAGE: 81205 — THE BOEING COMPANY DIV DEFENSE (USA)
SPECIFICATIONS
materialIRON ALLOY 660 OVERALL
head_styleFLAT COUNTERSUNK
grip_length1.240 INCHES MINIMUM AND 1.260 INCHES MAXIMUM IN
thread_class3A A
grip_diameter0.2485 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN
head_diameter0.354 INCHES MINIMUM AND 0.399 INCHES MAXIMUM IN
thread_length0.364 INCHES MINIMUM AND 0.414 INCHES MAXIMUM IN
surface_finish32.0 MICROINCHES GRIP
fastener_length1.624 INCHES MINIMUM AND 1.654 INCHES MAXIMUM IN
thread_directionRIGHT-HAND
countersink_angle100.0 DEGREES NOMINAL
surface_treatmentCADMIUM AND CHROMATE OVERALL
NSN5305-01-049-5665
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: BACB30LL4-20 · 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: 1.624 INCHES MINIMUM AND 1.654 INCHES MAXIMUM IN
•
SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: QQ-P-416,TYPE 2,CLASS 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
•
THREAD LENGTH: 0.364 INCHES MINIMUM AND 0.414 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 LENGTH1.624 INCHES MINIMUM AND 1.654 INCHES MAXIMUM IN
SURFACE TREATMENT DOCUMENT AND CLASSIFICATIONQQ-P-416,TYPE 2,CLASS 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
THREAD LENGTH0.364 INCHES MINIMUM AND 0.414 INCHES MAXIMUM IN
NOMINAL THREAD DIAMETER0.250 INCHES IN
HEAD STYLEFLAT COUNTERSUNK
THREAD DIRECTIONRIGHT-HAND
SPECIFICATION/STANDARD DATA81205-BACB30LL PROFESSIONAL/INDUSTRIAL ASSOCIATION STANDARD
GRIP LENGTH1.240 INCHES MINIMUM AND 1.260 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

No substitute or cross-reference records for this part.

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 BACB30LL4-20?
BACB30LL4-20 is a SCREW,CLOSE TOLERANCE.
What is the NSN for BACB30LL4-20?
BACB30LL4-20 is cataloged in the U.S. Government catalog under NSN 5305-01-049-5665. 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.