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1/4 20UNC 3A X 1 IN LG — Technical Data Sheet

✓ 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 SCREW,MACHINE is a the manufacturer industrial component. Key specifications include material: NICKEL ALLOY 400 OVERALL, head_style: FLAT COUNTERSUNK, thread_class: 3A A, head_diameter: 0.480 INCHES MINIMUM AND 0.531 INCHES MAXIMUM IN, thread_length: 0.739 INCHES MINIMUM AND 1.000 INCHES MAXIMUM IN, screw_material: NICKEL ALLOY 400. This product is currently in active production with full OEM support.

This part is cataloged in the Federal Logistics Information System under NSN 5305-01-321-6226, 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
1/4 20UNC 3A X 1 IN LG
NSN: 5305-01-321-6226
FSC: 5305
CAGE: 80204 — AMERICAN NATIONAL STANDARDS INSTITUTE INCORPORATED DBA AMERICAN NATIONAL STANDARDS INSTITUTE (USA)
SPECIFICATIONS
materialNICKEL ALLOY 400 OVERALL
head_styleFLAT COUNTERSUNK
thread_class3A A
head_diameter0.480 INCHES MINIMUM AND 0.531 INCHES MAXIMUM IN
thread_length0.739 INCHES MINIMUM AND 1.000 INCHES MAXIMUM IN
screw_materialNICKEL ALLOY 400
fastener_length1.000 INCHES NOMINAL IN
thread_directionRIGHT-HAND
countersink_angle80.0 DEGREES MINIMUM AND 84.0 DEGREES MAXIMUM
width_across_flats0.156 INCHES NOMINAL IN
internal_drive_styleHEXAGON
nominal_thread_diameter0.250 INCHES IN
NSN5305-01-321-6226
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: 1/4 20UNC 3A X 1 IN LG · 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
•
THREAD SERIES DESIGNATOR: UNIFIED NATIONAL COARSE (UNC)
•
FASTENER LENGTH: 1.000 INCHES NOMINAL IN
•
MINIMUM TENSILE STRENGTH: 80000 POUNDS PER SQUARE INCH LBS
•
INTERNAL DRIVE STYLE: SLOT
•
HEAD DIAMETER: 0.452 INCHES MINIMUM AND 0.507 INCHES MAXIMUM IN
•
THREAD QUANTITY PER INCH: 20
•
THREAD CLASS: 3A A
•
COUNTERSINK ANGLE: 80.0 DEGREES MINIMUM AND 82.0 DEGREES MAXIMUM
TECHNICAL CHARACTERISTICS
THREAD SERIES DESIGNATORUNIFIED NATIONAL COARSE (UNC)
FASTENER LENGTH1.000 INCHES NOMINAL IN
MINIMUM TENSILE STRENGTH80000 POUNDS PER SQUARE INCH LBS
INTERNAL DRIVE STYLESLOT
HEAD DIAMETER0.452 INCHES MINIMUM AND 0.507 INCHES MAXIMUM IN
THREAD QUANTITY PER INCH20
THREAD CLASS3A A
COUNTERSINK ANGLE80.0 DEGREES MINIMUM AND 82.0 DEGREES MAXIMUM
SCREW MATERIALNICKEL ALLOY 400
THREAD DIRECTIONRIGHT-HAND
VERIFIED SUBSTITUTES & CROSS-REFERENCES 4
FF-S-86 TYPE IVInterchangeableGOVERNMENT REGISTRY
interchangeable cross-reference
interchangeable
FF-S-86InterchangeableGOVERNMENT REGISTRY
interchangeable cross-reference
interchangeable
FF-S-92InterchangeableGOVERNMENT REGISTRY
Same NIIN cross-reference
interchangeable
845-4687407-257 1.000IN SCREWInterchangeableGOVERNMENT REGISTRY
Same NIIN cross-reference
interchangeable
LIFECYCLE
StatusACTIVEGOVERNMENT REGISTRY
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is 1/4 20UNC 3A X 1 IN LG?
1/4 20UNC 3A X 1 IN LG is a SCREW,MACHINE.
What parts can replace 1/4 20UNC 3A X 1 IN LG?
There are 4 known substitutes for 1/4 20UNC 3A X 1 IN LG: FF-S-86 TYPE IV, FF-S-86, FF-S-92 and 1 more. Substitute compatibility should be verified for your specific system.
What is the NSN for 1/4 20UNC 3A X 1 IN LG?
1/4 20UNC 3A X 1 IN LG is cataloged in the Federal Logistics Information System under NSN 5305-01-321-6226. 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: October 2026