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BACB30LR4U21 — SCREW,CLOSE TOLERANCE

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

BACB30LR4U21: 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: 1.302 INCHES MINIMUM AND 1.322 INCHES MAXIMUM IN, thread_class: 3A A, grip_diameter: 0.2490 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 5305-01-050-9652, 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
BACB30LR4U21
NSN: 5305-01-050-9652
FSC: 5305 — Screws
CAGE: 81205 — THE BOEING COMPANY DIV DEFENSE (USA)
SPECIFICATIONS
materialIRON ALLOY 660 OVERALL
head_styleFLAT COUNTERSUNK
grip_length1.302 INCHES MINIMUM AND 1.322 INCHES MAXIMUM IN
thread_class3A A
grip_diameter0.2490 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
fastener_length1.722 INCHES MINIMUM AND 1.752 INCHES MAXIMUM IN
thread_directionRIGHT-HAND
countersink_angle100.0 DEGREES NOMINAL
surface_treatmentPASSIVATE OVERALL
internal_drive_styleCROSS RECESS TYPE 1
NSN5305-01-050-9652
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: BACB30LR4U21 · 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: 1.722 INCHES MINIMUM AND 1.752 INCHES MAXIMUM IN
•
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
•
GRIP LENGTH: 1.302 INCHES MINIMUM AND 1.322 INCHES MAXIMUM IN
•
GRIP DIAMETER: 0.2490 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN
•
SURFACE TREATMENT: PASSIVATE OVERALL
TECHNICAL CHARACTERISTICS
FASTENER LENGTH1.722 INCHES MINIMUM AND 1.752 INCHES MAXIMUM IN
THREAD LENGTH0.400 INCHES MINIMUM AND 0.450 INCHES MAXIMUM IN
NOMINAL THREAD DIAMETER0.250 INCHES IN
HEAD STYLEFLAT COUNTERSUNK
THREAD DIRECTIONRIGHT-HAND
GRIP LENGTH1.302 INCHES MINIMUM AND 1.322 INCHES MAXIMUM IN
GRIP DIAMETER0.2490 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN
SURFACE TREATMENTPASSIVATE OVERALL
INTERNAL DRIVE STYLECROSS RECESS TYPE 1
COUNTERSINK ANGLE100.0 DEGREES NOMINAL
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
BACB3OLR4U21Reference 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 BACB30LR4U21?
BACB30LR4U21 is a SCREW,CLOSE TOLERANCE.
What parts can replace BACB30LR4U21?
There is 1 known substitute for BACB30LR4U21: BACB3OLR4U21. Substitute compatibility should be verified for your specific system.
What is the NSN for BACB30LR4U21?
BACB30LR4U21 is cataloged in the U.S. Government catalog under NSN 5305-01-050-9652. 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.