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1/4-20UNC-3A 1 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,CAP,SOCKET HEAD 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, fastener_length: 1.000 INCHES NOMINAL IN. This product is currently in active production with full OEM support.

This part is cataloged in the Federal Logistics Information System under NSN 5305-01-332-2167, 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 1 LG
NSN: 5305-01-332-2167
FSC: 5305
CAGE: 05047 — THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS (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
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
minimum_tensile_strength80000 POUNDS PER SQUARE INCH LBS
NSN5305-01-332-2167
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: 1/4-20UNC-3A 1 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
•
COUNTERSINK ANGLE: 80.0 DEGREES MINIMUM AND 84.0 DEGREES MAXIMUM
•
HEAD DIAMETER: 0.480 INCHES MINIMUM AND 0.531 INCHES MAXIMUM IN
•
THREAD QUANTITY PER INCH: 20
•
THREAD SERIES DESIGNATOR: UNIFIED NATIONAL COARSE (UNC)
•
NONDEFINITIVE SPEC/STD DATA: 4 TYPE
•
THREAD CLASS: 3A A
•
MATERIAL: NICKEL ALLOY 400 OVERALL
•
FASTENER LENGTH: 1.000 INCHES NOMINAL IN
TECHNICAL CHARACTERISTICS
COUNTERSINK ANGLE80.0 DEGREES MINIMUM AND 84.0 DEGREES MAXIMUM
HEAD DIAMETER0.480 INCHES MINIMUM AND 0.531 INCHES MAXIMUM IN
THREAD QUANTITY PER INCH20
THREAD SERIES DESIGNATORUNIFIED NATIONAL COARSE (UNC)
NONDEFINITIVE SPEC/STD DATA4 TYPE
THREAD CLASS3A A
MATERIALNICKEL ALLOY 400 OVERALL
FASTENER LENGTH1.000 INCHES NOMINAL IN
MINIMUM YIELD STRENGTH40000 POUNDS PER SQUARE INCH LBS
WIDTH ACROSS FLATS0.156 INCHES NOMINAL IN
VERIFIED SUBSTITUTES & CROSS-REFERENCES 16
NASM24671-78InterchangeableGOVERNMENT REGISTRY
interchangeable cross-reference
interchangeable
MS24671-78InterchangeableGOVERNMENT REGISTRY
interchangeable cross-reference
interchangeable
FF-S-86 TYPE IVInterchangeableGOVERNMENT REGISTRY
interchangeable cross-reference
interchangeable
51480InterchangeableGOVERNMENT REGISTRY
interchangeable cross-reference
interchangeable
100A905078InterchangeableGOVERNMENT REGISTRY
interchangeable cross-reference
interchangeable
92197A244InterchangeableGOVERNMENT REGISTRY
interchangeable 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 1 LG?
1/4-20UNC-3A 1 LG is a SCREW,CAP,SOCKET HEAD.
What parts can replace 1/4-20UNC-3A 1 LG?
There are 16 known substitutes for 1/4-20UNC-3A 1 LG: NASM24671-78, MS24671-78, FF-S-86 TYPE IV and 13 more. Substitute compatibility should be verified for your specific system.
What is the NSN for 1/4-20UNC-3A 1 LG?
1/4-20UNC-3A 1 LG is cataloged in the Federal Logistics Information System under NSN 5305-01-332-2167. This indicates validated use in U.S. government and defense supply chains.
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Last verified: October 2026