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BACB30NN4K21 — SCREW,CLOSE TOLERANCE

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

BACB30NN4K21: SCREW,CLOSE TOLERANCE.

The SCREW,CLOSE TOLERANCE is a the manufacturer industrial component. Key specifications include material: TITANIUM ALLOY OVERALL, head_style: FLAT COUNTERSUNK, grip_length: 1.3025 INCHES MINIMUM AND 1.3225 INCHES MAXIMUM IN, thread_class: 3A A, grip_diameter: 0.2485 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN, head_diameter: 0.465 INCHES MINIMUM AND 0.510 INCHES MAXIMUM IN. This part is cataloged in the U.S.

Government catalog under NSN 5305-01-232-9758, 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
BACB30NN4K21
NSN: 5305-01-232-9758
FSC: 5305 — Screws
CAGE: 81205 — THE BOEING COMPANY DIV DEFENSE (USA)
SPECIFICATIONS
materialTITANIUM ALLOY OVERALL
head_styleFLAT COUNTERSUNK
grip_length1.3025 INCHES MINIMUM AND 1.3225 INCHES MAXIMUM IN
thread_class3A A
grip_diameter0.2485 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN
head_diameter0.465 INCHES MINIMUM AND 0.510 INCHES MAXIMUM IN
thread_length0.425 INCHES NOMINAL IN
fastener_length1.7225 INCHES MINIMUM AND 1.7525 INCHES MAXIMUM IN
special_featuresIDENTIFY W/BLACK DYE OR PAINT ON-THREAD END
thread_directionRIGHT-HAND
countersink_angle99.0 DEGREES MINIMUM AND 101.0 DEGREES MAXIMUM
surface_treatmentALUMINUM OVERALL
NSN5305-01-232-9758
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: BACB30NN4K21 · 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
•
FASTENER LENGTH: 1.7225 INCHES MINIMUM AND 1.7525 INCHES MAXIMUM IN
•
THREAD LENGTH: 0.425 INCHES NOMINAL IN
•
MATERIAL DOCUMENT AND CLASSIFICATION: AMS 4928 ASSN STD SINGLE MATERIAL RESPONSE OR AMS 4967 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
•
NOMINAL THREAD DIAMETER: 0.250 INCHES IN
•
HEAD STYLE: FLAT COUNTERSUNK
•
THREAD DIRECTION: RIGHT-HAND
•
GRIP LENGTH: 1.3025 INCHES MINIMUM AND 1.3225 INCHES MAXIMUM IN
•
GRIP DIAMETER: 0.2485 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN
TECHNICAL CHARACTERISTICS
FASTENER LENGTH1.7225 INCHES MINIMUM AND 1.7525 INCHES MAXIMUM IN
THREAD LENGTH0.425 INCHES NOMINAL IN
MATERIAL DOCUMENT AND CLASSIFICATIONAMS 4928 ASSN STD SINGLE MATERIAL RESPONSE OR AMS 4967 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
NOMINAL THREAD DIAMETER0.250 INCHES IN
HEAD STYLEFLAT COUNTERSUNK
THREAD DIRECTIONRIGHT-HAND
GRIP LENGTH1.3025 INCHES MINIMUM AND 1.3225 INCHES MAXIMUM IN
GRIP DIAMETER0.2485 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN
SPECIAL FEATURESIDENTIFY W/BLACK DYE OR PAINT ON-THREAD END
SURFACE TREATMENTALUMINUM OVERALL
OTHER ITEMS IN FSC 5305 — Screws
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5305-00-001-5016 5305-00-001-9160 5305-00-001-9629 5305-00-001-9742 5305-00-001-9768 5305-00-003-4306 5305-00-003-6694 5305-00-003-6753
SUBSTITUTES & CROSS-REFERENCES

No substitute or cross-reference records for this part.

LIFECYCLE
NSN statusActive· U.S. Government catalog
No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is BACB30NN4K21?
BACB30NN4K21 is a SCREW,CLOSE TOLERANCE.
What is the NSN for BACB30NN4K21?
BACB30NN4K21 is cataloged in the U.S. Government catalog under NSN 5305-01-232-9758. 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.