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HP6551C3-768 — SCREW,SHOULDER

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

HP6551C3-768: SCREW,SHOULDER.

The SCREW,SHOULDER is a the manufacturer industrial component. Key specifications include material: STEEL COMP 4037 OR STEEL COMP 8740 OVERALL, head_style: FLAT COUNTERSUNK, thread_class: 3A A, head_diameter: 0.276 INCHES NOMINAL IN, thread_length: 0.285 INCHES MINIMUM AND 0.351 INCHES MAXIMUM IN, shoulder_shape: ROUND FIRST SHOULDER. This part is cataloged in the U.S.

Government catalog under NSN 5305-00-151-8664, 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
HP6551C3-768
NSN: 5305-00-151-8664
FSC: 5305 — Screws
CAGE: 0ZC92 — HEARTLAND PRECISION FASTENERS INC (USA)
SPECIFICATIONS
materialSTEEL COMP 4037 OR STEEL COMP 8740 OVERALL
head_styleFLAT COUNTERSUNK
thread_class3A A
head_diameter0.276 INCHES NOMINAL IN
thread_length0.285 INCHES MINIMUM AND 0.351 INCHES MAXIMUM IN
shoulder_shapeROUND FIRST SHOULDER
fastener_length1.016 INCHES MINIMUM AND 1.046 INCHES MAXIMUM IN
hardness_rating33.0 ROCKWELL C MINIMUM AND 37.0 ROCKWELL C MAXIMUM OVERALL
shoulder_length0.193 INCHES MINIMUM AND 0.195 INCHES MAXIMUM FIRST SHOULDER IN
thread_directionRIGHT-HAND
countersink_angle100.0 DEGREES NOMINAL
shoulder_diameter0.655 INCHES MINIMUM AND 0.685 INCHES MAXIMUM FIRST SHOULDER IN
NSN5305-00-151-8664
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: HP6551C3-768 · 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: 1.016 INCHES MINIMUM AND 1.046 INCHES MAXIMUM IN
•
SHOULDER LENGTH: 0.193 INCHES MINIMUM AND 0.195 INCHES MAXIMUM FIRST SHOULDER IN
•
SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: QQ-P-416,TY 2,CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
•
SHOULDER DIAMETER: 0.655 INCHES MINIMUM AND 0.685 INCHES MAXIMUM FIRST SHOULDER IN
•
THREAD LENGTH: 0.285 INCHES MINIMUM AND 0.351 INCHES MAXIMUM IN
•
SHOULDER SHAPE: ROUND FIRST SHOULDER
•
HARDNESS RATING: 33.0 ROCKWELL C MINIMUM AND 37.0 ROCKWELL C MAXIMUM OVERALL
•
NOMINAL THREAD DIAMETER: 0.190 INCHES IN
TECHNICAL CHARACTERISTICS
FASTENER LENGTH1.016 INCHES MINIMUM AND 1.046 INCHES MAXIMUM IN
SHOULDER LENGTH0.193 INCHES MINIMUM AND 0.195 INCHES MAXIMUM FIRST SHOULDER IN
SURFACE TREATMENT DOCUMENT AND CLASSIFICATIONQQ-P-416,TY 2,CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
SHOULDER DIAMETER0.655 INCHES MINIMUM AND 0.685 INCHES MAXIMUM FIRST SHOULDER IN
THREAD LENGTH0.285 INCHES MINIMUM AND 0.351 INCHES MAXIMUM IN
SHOULDER SHAPEROUND FIRST SHOULDER
HARDNESS RATING33.0 ROCKWELL C MINIMUM AND 37.0 ROCKWELL C MAXIMUM OVERALL
NOMINAL THREAD DIAMETER0.190 INCHES IN
HEAD STYLEFLAT COUNTERSUNK
THREAD DIRECTIONRIGHT-HAND
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 2
B1990-9Reference document
Same NSN cross-reference
Reference document — Secondary reference
GS551C3-768Reference document
Same NSN cross-reference
Reference document — Vendor item drawing 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 HP6551C3-768?
HP6551C3-768 is a SCREW,SHOULDER.
What parts can replace HP6551C3-768?
There are 2 known substitutes for HP6551C3-768: B1990-9, GS551C3-768. Substitute compatibility should be verified for your specific system.
What is the NSN for HP6551C3-768?
HP6551C3-768 is cataloged in the U.S. Government catalog under NSN 5305-00-151-8664. 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.