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Technical Data Sheet
PartsTable / COMPONENT / 277A-20
277A-20 ✓ Verified by PartsTable
— · BOLT SCREW
WHAT YOU NEED TO KNOW
Grade/class stamped on head determines strength Metric and imperial threads look similar — measure pitch
Verify thread pitch — metric != imperial
PRODUCT OVERVIEW

The STUD,BALL is a the manufacturer industrial component. Key specifications include material: COPPER ALLOY AND STEEL, thread_class: 2A LOCATION NOT OTHERWISE SPECIFIED A, head_diameter: 0.625 INCHES NOMINAL IN, neck_diameter: 0.391 INCHES NOMINAL IN, thread_length: 0.875 INCHES NOMINAL LOCATION NOT OTHERWISE SPECIFIED IN, overall_length: 2.250 INCHES NOMINAL IN. This product is currently in active production with full OEM support.

This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 5307-01-389-3445, 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
277A-20
NSN: 5307-01-389-3445
FSC: 5307
CAGE: 55242 — ISOMETRICS INC (USA)
SPECIFICATIONS
materialCOPPER ALLOY AND STEEL
thread_class2A LOCATION NOT OTHERWISE SPECIFIED A
head_diameter0.625 INCHES NOMINAL IN
neck_diameter0.391 INCHES NOMINAL IN
thread_length0.875 INCHES NOMINAL LOCATION NOT OTHERWISE SPECIFIED IN
overall_length2.250 INCHES NOMINAL IN
style_designatorBALL
thread_directionRIGHT-HAND LOCATION NOT OTHERWISE SPECIFIED
nominal_thread_size0.375 INCHES LOCATION NOT OTHERWISE SPECIFIED IN
distance_across_flats0.625 INCHES NOMINAL IN
thread_quantity_per_inch16 LOCATION NOT OTHERWISE SPECIFIED
thread_series_designatorUNIFIED NATIONAL COARSE (UNC) LOCATION NOT OTHERWISE SPECIFIED
NSN5307-01-389-3445
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: 277A-20 · 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
•
NECK DIAMETER: 0.391 INCHES NOMINAL IN
•
THREAD SERIES DESIGNATOR: UNIFIED NATIONAL COARSE (UNC) LOCATION NOT OTHERWISE SPECIFIED
•
DISTANCE ACROSS FLATS: 0.625 INCHES NOMINAL IN
•
THREAD DIRECTION: RIGHT-HAND LOCATION NOT OTHERWISE SPECIFIED
•
THREAD QUANTITY PER INCH: 16 LOCATION NOT OTHERWISE SPECIFIED
•
NOMINAL THREAD SIZE: 0.375 INCHES LOCATION NOT OTHERWISE SPECIFIED IN
•
DISTANCE FROM SPHERICAL HEAD CENTERLINE TO HEAD END: 0.312 INCHES NOMINAL IN
TECHNICAL CHARACTERISTICS (FLIS)
NECK DIAMETER0.391 INCHES NOMINAL IN
THREAD SERIES DESIGNATORUNIFIED NATIONAL COARSE (UNC) LOCATION NOT OTHERWISE SPECIFIED
DISTANCE ACROSS FLATS0.625 INCHES NOMINAL IN
THREAD DIRECTIONRIGHT-HAND LOCATION NOT OTHERWISE SPECIFIED
OVERALL LENGTH2.250 INCHES NOMINAL IN
THREAD QUANTITY PER INCH16 LOCATION NOT OTHERWISE SPECIFIED
NOMINAL THREAD SIZE0.375 INCHES LOCATION NOT OTHERWISE SPECIFIED IN
DISTANCE FROM SPHERICAL HEAD CENTERLINE TO HEAD END0.312 INCHES NOMINAL IN
STYLE DESIGNATORBALL
THREAD CLASS2A LOCATION NOT OTHERWISE SPECIFIED A
VERIFIED SUBSTITUTES & CROSS-REFERENCES 11
7523Interchangeable
interchangeable cross-reference
interchangeable
4841Interchangeable
interchangeable cross-reference
interchangeable
4841-1Interchangeable
interchangeable cross-reference
interchangeable
531682-163NDInterchangeable
interchangeable cross-reference
interchangeable
7524Interchangeable
interchangeable cross-reference
interchangeable
GPN7523Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusACTIVE
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is 277A-20?
277A-20 is a STUD,BALL.
What parts can replace 277A-20?
There are 11 known substitutes for 277A-20: 7523, 4841, 4841-1 and 8 more. Substitute compatibility should be verified for your specific system.
What is the NSN for 277A-20?
277A-20 is cataloged in the Federal Logistics Information System (FLIS) under NSN 5307-01-389-3445. This indicates validated use in U.S. government and defense supply chains.
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✓ Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
PartsTable Design LLC · partstable.com
Last verified: July 2026