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76121-4-3 — SCREW,CLOSE TOLERANCE

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

76121-4-3: SCREW,CLOSE TOLERANCE.

The SCREW,CLOSE TOLERANCE is a the manufacturer industrial component. Key specifications include material: IRON ALLOY 660 OVERALL, grip_length: 0.178 INCHES MINIMUM AND 0.198 INCHES MAXIMUM IN, thread_class: 3A A, grip_diameter: 0.2490 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN, head_diameter: 0.350 INCHES MINIMUM AND 0.398 INCHES MAXIMUM IN, surface_finish: 32.0 MICROINCHES GRIP. This part is cataloged in the U.S.

Government catalog under NSN 5305-01-043-7715, 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
76121-4-3
NSN: 5305-01-043-7715
FSC: 5305 — Screws
CAGE: 80539 — SPS TECHNOLOGIES, LLC DBA AEROSPACE FASTENERS GROUP DIV AEROSPACE - SANTA ANA (USA)
SPECIFICATIONS
materialIRON ALLOY 660 OVERALL
grip_length0.178 INCHES MINIMUM AND 0.198 INCHES MAXIMUM IN
thread_class3A A
grip_diameter0.2490 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN
head_diameter0.350 INCHES MINIMUM AND 0.398 INCHES MAXIMUM IN
surface_finish32.0 MICROINCHES GRIP
hardness_rating36.0 ROCKWELL C MINIMUM AND 40.0 ROCKWELL C MAXIMUM OVERALL
countersink_angle100.0 DEGREES NOMINAL
surface_treatmentPASSIVATE OVERALL
internal_drive_styleHIGH-TORQUE
nominal_thread_diameter0.250 INCHES IN
minimum_tensile_strength160000 POUNDS PER SQUARE INCH LBS
NSN5305-01-043-7715
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: 76121-4-3 · 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
•
SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: QQ-P-35 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
•
HARDNESS RATING: 36.0 ROCKWELL C MINIMUM AND 40.0 ROCKWELL C MAXIMUM OVERALL
•
SHANK UNTHREADED HOLE DIAMETER: 0.076 INCHES MINIMUM AND 0.086 INCHES MAXIMUM FIRST HOLE IN
•
MATERIAL DOCUMENT AND CLASSIFICATION: AMS 5732 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
•
NOMINAL THREAD DIAMETER: 0.250 INCHES IN
•
SPECIFICATION/STANDARD DATA: 26512-GB510B MANUFACTURERS STANDARD
TECHNICAL CHARACTERISTICS
SURFACE FINISH32.0 MICROINCHES THREADS
SURFACE FINISH32.0 MICROINCHES GRIP
SURFACE TREATMENT DOCUMENT AND CLASSIFICATIONQQ-P-35 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
HARDNESS RATING36.0 ROCKWELL C MINIMUM AND 40.0 ROCKWELL C MAXIMUM OVERALL
SHANK UNTHREADED HOLE DIAMETER0.076 INCHES MINIMUM AND 0.086 INCHES MAXIMUM FIRST HOLE IN
MATERIAL DOCUMENT AND CLASSIFICATIONAMS 5732 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
NOMINAL THREAD DIAMETER0.250 INCHES IN
SPECIFICATION/STANDARD DATA26512-GB510B MANUFACTURERS STANDARD
GRIP LENGTH0.178 INCHES MINIMUM AND 0.198 INCHES MAXIMUM IN
GRIP DIAMETER0.2490 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN
OTHER ITEMS IN FSC 5305 — Screws
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5305-00-001-5016 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 2
GB510BF4-3Reference document
Same NSN cross-reference
Reference document — Vendor item drawing reference
BM19047C4H3Reference document
Same NSN cross-reference
Reference document — Secondary reference
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Normally procured from the manufacturer (OEM)No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 76121-4-3?
76121-4-3 is a SCREW,CLOSE TOLERANCE.
What parts can replace 76121-4-3?
There are 2 known substitutes for 76121-4-3: GB510BF4-3, BM19047C4H3. Substitute compatibility should be verified for your specific system.
What is the NSN for 76121-4-3?
76121-4-3 is cataloged in the U.S. Government catalog under NSN 5305-01-043-7715. 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.