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C306-6 — NUT,SELF-LOCKING,EXTENDED WASHER

✓ Government record, cited
— · NUT WASHER
PRODUCT OVERVIEW

C306-6: NUT,SELF-LOCKING,EXTENDED WASHER.

NUT,SELF-LOCKING,EXTENDED WASHER. Key specifications include material: STEEL COMP 601 OVERALL, nut_style: DOUBLE HEXAGON, lubrication: DRY FILM LUBRICANT, temp_rating: 450.0 FAHRENHEIT NOMINAL DEGF, thread_class: 3B, thread_series: UNIFIED NATIONAL JOINT FINE (UNJF). This part is cataloged in the U.S.

Government catalog under NSN 5310-00-931-8607, 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
C306-6
NSN: 5310-00-931-8607
FSC: 5310 — Nuts and Washers
CAGE: 81755 — LOCKHEED MARTIN CORPORATION DIV LOCKHEED MARTIN AERONAUTICS COMPANY (USA)
SPECIFICATIONS
materialSTEEL COMP 601 OVERALL
nut_styleDOUBLE HEXAGON
lubricationDRY FILM LUBRICANT
temp_rating450.0 FAHRENHEIT NOMINAL DEGF
thread_class3B
thread_seriesUNIFIED NATIONAL JOINT FINE (UNJF)
overall_height0.725 INCHES MAXIMUM IN
locking_featurePREVAILING TORQUE ALL METAL DESIGN
thread_directionRIGHT-HAND
washer_thickness0.031 INCHES MINIMUM IN
surface_treatmentCADMIUM AND CHROMATE OVERALL
width_across_flats0.492 INCHES MINIMUM AND 0.504 INCHES MAXIMUM IN
NSN5310-00-931-8607
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: C306-6 · 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
•
LUBRICATION: DRY FILM LUBRICANT
•
WASHER OUTSIDE DIAMETER: 0.725 INCHES MAXIMUM IN
•
WIDTH ACROSS FLATS: 0.492 INCHES MINIMUM AND 0.504 INCHES MAXIMUM IN
•
THREAD SERIES: UNIFIED NATIONAL JOINT FINE (UNJF)
•
TEMP RATING: 450.0 FAHRENHEIT NOMINAL DEGF
•
WASHER THICKNESS: 0.031 INCHES MINIMUM IN
•
MATERIAL DOCUMENT AND CLASSIFICATION: AMS 6304 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
TECHNICAL CHARACTERISTICS
LUBRICATIONDRY FILM LUBRICANT
OVERALL HEIGHT0.725 INCHES MAXIMUM IN
WASHER OUTSIDE DIAMETER0.725 INCHES MAXIMUM IN
WIDTH ACROSS FLATS0.492 INCHES MINIMUM AND 0.504 INCHES MAXIMUM IN
THREAD SERIESUNIFIED NATIONAL JOINT FINE (UNJF)
TEMP RATING450.0 FAHRENHEIT NOMINAL DEGF
WASHER THICKNESS0.031 INCHES MINIMUM IN
MATERIAL DOCUMENT AND CLASSIFICATIONAMS 6304 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
THREAD DIRECTIONRIGHT-HAND
NOMINAL THREAD SIZE0.375 INCHES IN
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 2
FNF26-624Reference document
Same NSN cross-reference
Reference document — Secondary reference
LH7896-6Reference 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 C306-6?
C306-6 is a NUT,SELF-LOCKING,EXTENDED WASHER.
What parts can replace C306-6?
There are 2 known substitutes for C306-6: FNF26-624, LH7896-6. Substitute compatibility should be verified for your specific system.
What is the NSN for C306-6?
C306-6 is cataloged in the U.S. Government catalog under NSN 5310-00-931-8607. This indicates validated use in U.S. government and defense supply chains.
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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.