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BACB30KK8-4 — BOLT,SHOULDER

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

BACB30KK8-4: BOLT,SHOULDER.

The BOLT,SHOULDER is a the manufacturer industrial component. Key specifications include material: STEEL COMP 4130 OR STEEL COMP 8630 OR STEEL COMP 8735 OR STEEL COMP 8740 OVERALL, head_style: FLAT CHAMFER, head_height: 0.059 INCHES MINIMUM AND 0.069 INCHES MAXIMUM IN, thread_class: 3A A, head_diameter: 0.387 INCHES MINIMUM AND 0.412 INCHES MAXIMUM IN, thread_length: 0.395 INCHES MINIMUM IN. This part is cataloged in the U.S.

Government catalog under NSN 5306-00-401-7978, 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
BACB30KK8-4
NSN: 5306-00-401-7978
FSC: 5306 — Bolts
CAGE: 81205 — THE BOEING COMPANY DIV DEFENSE (USA)
SPECIFICATIONS
materialSTEEL COMP 4130 OR STEEL COMP 8630 OR STEEL COMP 8735 OR STEEL COMP 8740 OVERALL
head_styleFLAT CHAMFER
head_height0.059 INCHES MINIMUM AND 0.069 INCHES MAXIMUM IN
thread_class3A A
head_diameter0.387 INCHES MINIMUM AND 0.412 INCHES MAXIMUM IN
thread_length0.395 INCHES MINIMUM IN
shoulder_shapeROUND FIRST SHOULDER
fastener_length0.645 INCHES NOMINAL IN
hardness_rating31.0 ROCKWELL C NOMINAL OVERALL
shoulder_length0.740 INCHES MINIMUM AND 0.760 INCHES MAXIMUM FIRST SHOULDER IN
thread_directionRIGHT-HAND
shoulder_diameter0.279 INCHES MINIMUM AND 0.280 INCHES MAXIMUM FIRST SHOULDER IN
NSN5306-00-401-7978
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: BACB30KK8-4 · 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
•
HEAD HEIGHT: 0.059 INCHES MINIMUM AND 0.069 INCHES MAXIMUM IN
•
FASTENER LENGTH: 0.645 INCHES NOMINAL IN
•
SHOULDER LENGTH: 0.740 INCHES MINIMUM AND 0.760 INCHES MAXIMUM FIRST SHOULDER IN
•
SHOULDER DIAMETER: 0.279 INCHES MINIMUM AND 0.280 INCHES MAXIMUM FIRST SHOULDER IN
•
THREAD LENGTH: 0.395 INCHES MINIMUM IN
•
SHOULDER SHAPE: ROUND FIRST SHOULDER
•
HARDNESS RATING: 31.0 ROCKWELL C NOMINAL OVERALL
•
MATERIAL DOCUMENT AND CLASSIFICATION: MIL-S-6758 MIL SPEC 1ST MATERIAL RESPONSE OR MIL-S-6050 MIL SPEC 2ND MATERIAL RESPONSE OR MIL-S-6098 MIL SPEC 3RD MATERIAL RESPONSE OR MIL-S-6049 MIL SPEC 4TH MATERIAL RESPONSE OVERALL
TECHNICAL CHARACTERISTICS
HEAD HEIGHT0.059 INCHES MINIMUM AND 0.069 INCHES MAXIMUM IN
FASTENER LENGTH0.645 INCHES NOMINAL IN
SHOULDER LENGTH0.740 INCHES MINIMUM AND 0.760 INCHES MAXIMUM FIRST SHOULDER IN
SHOULDER DIAMETER0.279 INCHES MINIMUM AND 0.280 INCHES MAXIMUM FIRST SHOULDER IN
THREAD LENGTH0.395 INCHES MINIMUM IN
SHOULDER SHAPEROUND FIRST SHOULDER
HARDNESS RATING31.0 ROCKWELL C NOMINAL OVERALL
MATERIAL DOCUMENT AND CLASSIFICATIONMIL-S-6758 MIL SPEC 1ST MATERIAL RESPONSE OR MIL-S-6050 MIL SPEC 2ND MATERIAL RESPONSE OR MIL-S-6098 MIL SPEC 3RD MATERIAL RESPONSE OR MIL-S-6049 MIL SPEC 4TH MATERIAL RESPONSE OVERALL
NOMINAL THREAD DIAMETER0.250 INCHES IN
HEAD STYLEFLAT CHAMFER
OTHER ITEMS IN FSC 5306 — Bolts
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5306-00-001-1276 5306-00-001-1949 5306-00-001-1988 5306-00-001-1989 5306-00-001-1990 5306-00-001-1991 5306-00-001-1993 5306-00-001-2017
SUBSTITUTES & CROSS-REFERENCES 2
HL218-8-4Reference document
Same NSN cross-reference
Reference document — Secondary reference
65960-8-4Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
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 BACB30KK8-4?
BACB30KK8-4 is a BOLT,SHOULDER.
What parts can replace BACB30KK8-4?
There are 2 known substitutes for BACB30KK8-4: HL218-8-4, 65960-8-4. Substitute compatibility should be verified for your specific system.
What is the NSN for BACB30KK8-4?
BACB30KK8-4 is cataloged in the U.S. Government catalog under NSN 5306-00-401-7978. 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.