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4F81B1 — NUT,PLAIN,KNURLED

✓ Government record, cited
— · NUT WASHER
PRODUCT OVERVIEW

4F81B1: NUT,PLAIN,KNURLED.

The NUT,PLAIN,KNURLED is a the manufacturer industrial component. Key specifications include material: COPPER ALLOY OVERALL, nut_style: KNURLED, knurl_width: 0.156 INCHES NOMINAL IN, nut_diameter: 0.625 INCHES NOMINAL IN, thread_class: 2B, nut_thickness: 0.375 INCHES NOMINAL IN. This part is cataloged in the U.S.

Government catalog under NSN 5310-00-796-4786, 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
4F81B1
NSN: 5310-00-796-4786
FSC: 5310 — Nuts and Washers
CAGE: 10001 — NAVAIR AND NAVSEA MANAGED ORIGINAL DESIGN ACTIVITY DWG NOT MATERIAL/PARTS SUPPLIER (USA)
SPECIFICATIONS
materialCOPPER ALLOY OVERALL
nut_styleKNURLED
knurl_width0.156 INCHES NOMINAL IN
nut_diameter0.625 INCHES NOMINAL IN
thread_class2B
nut_thickness0.375 INCHES NOMINAL IN
thread_seriesUNIFIED NATIONAL COARSE (UNC)
thread_directionRIGHT-HAND
countersink_angle45.0 DEGREES NOMINAL NUT
nominal_thread_size0.250 INCHES IN
counterbore_diameter0.375 INCHES NOMINAL NUT IN
nut_counterbore_depth0.016 INCHES NOMINAL NUT IN
NSN5310-00-796-4786
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: 4F81B1 · OEM ⚠ VERIFY BEFORE ORDERING Grade matters for torque spec — don't mix grades. A Grade 5 nut on a Grade 8 bolt weakens the joint. Lock nuts, wing nuts, and castle nuts are NOT interchangeable with standard hex ✓ BROKER TIP Match nut to bolt thread class and material. Stainless bolt + zinc nut = galvanic corrosion. Always verify finish matches (plain, zinc, hot-dip galvanized) PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
THREAD SERIES: UNIFIED NATIONAL COARSE (UNC)
•
MATERIAL DOCUMENT AND CLASSIFICATION: QQ-B-626 FED SPEC SINGLE MATERIAL RESPONSE OVERALL
•
NUT COUNTERBORE DEPTH: 0.016 INCHES NOMINAL NUT IN
•
THREAD DIRECTION: RIGHT-HAND
•
NOMINAL THREAD SIZE: 0.250 INCHES IN
•
NUT DIAMETER: 0.625 INCHES NOMINAL IN
•
COUNTERBORE DIAMETER: 0.375 INCHES NOMINAL NUT IN
•
NUT THICKNESS: 0.375 INCHES NOMINAL IN
TECHNICAL CHARACTERISTICS
THREAD SERIESUNIFIED NATIONAL COARSE (UNC)
MATERIAL DOCUMENT AND CLASSIFICATIONQQ-B-626 FED SPEC SINGLE MATERIAL RESPONSE OVERALL
NUT COUNTERBORE DEPTH0.016 INCHES NOMINAL NUT IN
THREAD DIRECTIONRIGHT-HAND
NOMINAL THREAD SIZE0.250 INCHES IN
NUT DIAMETER0.625 INCHES NOMINAL IN
COUNTERBORE DIAMETER0.375 INCHES NOMINAL NUT IN
NUT THICKNESS0.375 INCHES NOMINAL IN
COUNTERSINK ANGLE45.0 DEGREES NOMINAL NUT
PART NAME ASSIGNED BY CONTROLLING AGENCYNAVY SPECIAL PROJECT
OTHER ITEMS IN FSC 5310 — Nuts and Washers
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5310-00-000-0040 5310-00-000-0077 5310-00-000-0079 5310-00-000-1146 5310-00-000-3815 5310-00-000-4532 5310-00-000-4540
SUBSTITUTES & CROSS-REFERENCES 1
64A98B780-1Reference document
Same NSN cross-reference
Reference document — Secondary reference
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Normally procured from the manufacturer (OEM)No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 4F81B1?
4F81B1 is a NUT,PLAIN,KNURLED.
What parts can replace 4F81B1?
There is 1 known substitute for 4F81B1: 64A98B780-1. Substitute compatibility should be verified for your specific system.
What is the NSN for 4F81B1?
4F81B1 is cataloged in the U.S. Government catalog under NSN 5310-00-796-4786. 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.