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GS551P4-621 — SCREW,CLOSE TOLERANCE

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

GS551P4-621: SCREW,CLOSE TOLERANCE.

The SCREW,CLOSE TOLERANCE is a the manufacturer industrial component. Key specifications include material: STEEL COMP 4037 OVERALL, head_style: FLAT COUNTERSUNK, grip_length: 0.545 INCHES MINIMUM AND 0.575 INCHES MAXIMUM IN, thread_class: 2A A, grip_diameter: 0.2540 INCHES MINIMUM AND 0.2550 INCHES MAXIMUM IN, head_diameter: 0.357 INCHES NOMINAL IN. This part is cataloged in the U.S.

Government catalog under NSN 5305-00-151-8656, 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
GS551P4-621
NSN: 5305-00-151-8656
FSC: 5305 — Screws
CAGE: 06725 — SPS TECHNOLOGIES, LLC DBA AIR INDUSTRIES COMPANY DIV AIR INDUSTRIES COMPANY (USA)
SPECIFICATIONS
materialSTEEL COMP 4037 OVERALL
head_styleFLAT COUNTERSUNK
grip_length0.545 INCHES MINIMUM AND 0.575 INCHES MAXIMUM IN
thread_class2A A
grip_diameter0.2540 INCHES MINIMUM AND 0.2550 INCHES MAXIMUM IN
head_diameter0.357 INCHES NOMINAL IN
thread_length0.379 INCHES MINIMUM AND 0.439 INCHES MAXIMUM IN
fastener_length0.954 INCHES MINIMUM AND 0.984 INCHES MAXIMUM IN
hardness_rating33.0 ROCKWELL C MINIMUM OVERALL
special_featuresCOLOR BLACK,SURFACE OF HEAD
thread_directionRIGHT-HAND
countersink_angle99.0 DEGREES MINIMUM AND 101.0 DEGREES MAXIMUM
NSN5305-00-151-8656
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: GS551P4-621 · 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: 0.954 INCHES MINIMUM AND 0.984 INCHES MAXIMUM IN
•
SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: QQ-P-416,TY 2,CL 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
•
THREAD LENGTH: 0.379 INCHES MINIMUM AND 0.439 INCHES MAXIMUM IN
•
HARDNESS RATING: 33.0 ROCKWELL C MINIMUM OVERALL
•
MATERIAL DOCUMENT AND CLASSIFICATION: AISI ASSN STD SINGLE MATERIAL RESPONSE OVERALL
•
NOMINAL THREAD DIAMETER: 0.250 INCHES IN
•
HEAD STYLE: FLAT COUNTERSUNK
•
THREAD DIRECTION: RIGHT-HAND
TECHNICAL CHARACTERISTICS
FASTENER LENGTH0.954 INCHES MINIMUM AND 0.984 INCHES MAXIMUM IN
SURFACE TREATMENT DOCUMENT AND CLASSIFICATIONQQ-P-416,TY 2,CL 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
THREAD LENGTH0.379 INCHES MINIMUM AND 0.439 INCHES MAXIMUM IN
HARDNESS RATING33.0 ROCKWELL C MINIMUM OVERALL
MATERIAL DOCUMENT AND CLASSIFICATIONAISI ASSN STD SINGLE MATERIAL RESPONSE OVERALL
NOMINAL THREAD DIAMETER0.250 INCHES IN
HEAD STYLEFLAT COUNTERSUNK
THREAD DIRECTIONRIGHT-HAND
GRIP LENGTH0.545 INCHES MINIMUM AND 0.575 INCHES MAXIMUM IN
GRIP DIAMETER0.2540 INCHES MINIMUM AND 0.2550 INCHES MAXIMUM IN
OTHER ITEMS IN FSC 5305 — Screws
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5305-00-000-0094 5305-00-000-1397 5305-00-000-2625 5305-00-000-3669 5305-00-000-3830 5305-00-000-3831
SUBSTITUTES & CROSS-REFERENCES 2
2R1465-8Reference document
Same NSN cross-reference
Reference document — Secondary reference
BM19070-4-621Reference 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 GS551P4-621?
GS551P4-621 is a SCREW,CLOSE TOLERANCE.
What parts can replace GS551P4-621?
There are 2 known substitutes for GS551P4-621: 2R1465-8, BM19070-4-621. Substitute compatibility should be verified for your specific system.
What is the NSN for GS551P4-621?
GS551P4-621 is cataloged in the U.S. Government catalog under NSN 5305-00-151-8656. 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.