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BACB30LU8-31 — SCREW,CLOSE TOLERANCE

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

BACB30LU8-31: SCREW,CLOSE TOLERANCE.

The SCREW,CLOSE TOLERANCE is a the manufacturer industrial component. Key specifications include head_style: FLAT COUNTERSUNK, grip_length: 1.928 INCHES MINIMUM AND 1.948 INCHES MAXIMUM IN, thread_class: 3A A, grip_diameter: 0.4982 INCHES MINIMUM AND 0.4991 INCHES MAXIMUM IN, head_diameter: 0.929 INCHES MINIMUM AND 1.024 INCHES MAXIMUM IN, thread_length: 0.489 INCHES MINIMUM AND 0.541 INCHES MAXIMUM IN. This part is cataloged in the U.S.

Government catalog under NSN 5305-00-409-3240, 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
BACB30LU8-31
NSN: 5305-00-409-3240
FSC: 5305 — Screws
CAGE: 81205 — THE BOEING COMPANY DIV DEFENSE (USA)
SPECIFICATIONS
materialSTEEL COMP 4140 OR STEEL COMP E4340 OR STEEL COMP 6150 OR STEEL COMP 8735 OR STEEL COMP 8740 OR STEEL COMP 4037 OVERALL
head_styleFLAT COUNTERSUNK
grip_length1.928 INCHES MINIMUM AND 1.948 INCHES MAXIMUM IN
thread_class3A A
grip_diameter0.4982 INCHES MINIMUM AND 0.4991 INCHES MAXIMUM IN
head_diameter0.929 INCHES MINIMUM AND 1.024 INCHES MAXIMUM IN
thread_length0.489 INCHES MINIMUM AND 0.541 INCHES MAXIMUM IN
surface_finish63.0 MICROINCHES GRIP
fastener_length2.437 INCHES MINIMUM AND 2.469 INCHES MAXIMUM IN
hardness_rating36.0 ROCKWELL C MINIMUM AND 40.0 ROCKWELL C MAXIMUM OVERALL
thread_directionRIGHT-HAND
countersink_angle99.0 DEGREES MINIMUM AND 101.0 DEGREES MAXIMUM
NSN5305-00-409-3240
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: BACB30LU8-31 · 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: 63.0 MICROINCHES GRIP
•
FASTENER LENGTH: 2.437 INCHES MINIMUM AND 2.469 INCHES MAXIMUM IN
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SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: QQ-P-416 TY 2 CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
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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
TECHNICAL CHARACTERISTICS
SURFACE FINISH63.0 MICROINCHES GRIP
FASTENER LENGTH2.437 INCHES MINIMUM AND 2.469 INCHES MAXIMUM IN
SURFACE TREATMENT DOCUMENT AND CLASSIFICATIONQQ-P-416 TY 2 CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
THREAD LENGTH0.489 INCHES MINIMUM AND 0.541 INCHES MAXIMUM IN
HARDNESS RATING36.0 ROCKWELL C MINIMUM AND 40.0 ROCKWELL C MAXIMUM OVERALL
MATERIAL DOCUMENT AND CLASSIFICATIONMIL-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 DIAMETER0.500 INCHES IN
HEAD STYLEFLAT COUNTERSUNK
THREAD DIRECTIONRIGHT-HAND
SPECIFICATION/STANDARD DATA81205-BACB30AB MANUFACTURERS STANDARD
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 1
BACB30ABP8-35AReference 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 BACB30LU8-31?
BACB30LU8-31 is a SCREW,CLOSE TOLERANCE.
What parts can replace BACB30LU8-31?
There is 1 known substitute for BACB30LU8-31: BACB30ABP8-35A. Substitute compatibility should be verified for your specific system.
What is the NSN for BACB30LU8-31?
BACB30LU8-31 is cataloged in the U.S. Government catalog under NSN 5305-00-409-3240. 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.