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K39781-7 — WASHER,CONVEX

✓ Government record, cited
— · NUT WASHER
PRODUCT OVERVIEW

K39781-7: WASHER,CONVEX.

The WASHER,CONVEX is a the manufacturer industrial component. Key specifications include radius: 0.515 INCHES MINIMUM AND 0.535 INCHES MAXIMUM IN, material: STEEL OVERALL, recess_angle: 88.000 DEGREES MINIMUM AND 92.000 DEGREES MAXIMUM, hole_diameter: 0.448 INCHES MINIMUM AND 0.458 INCHES MAXIMUM IN, surface_finish: 32.0 MICROINCHES ALL SURFACES, hardness_rating: 40.0 ROCKWELL C MINIMUM AND 46.0 ROCKWELL C MAXIMUM. This part is cataloged in the U.S.

Government catalog under NSN 5310-01-392-4127, 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
K39781-7
NSN: 5310-01-392-4127
NIINs: 013924127, 016590049
FSC: 5310 — Nuts and Washers
CAGE: 15653 — HOWMET GLOBAL FASTENING SYSTEMS INC (USA)
SPECIFICATIONS
radius0.515 INCHES MINIMUM AND 0.535 INCHES MAXIMUM IN
materialSTEEL OVERALL
recess_angle88.000 DEGREES MINIMUM AND 92.000 DEGREES MAXIMUM
hole_diameter0.448 INCHES MINIMUM AND 0.458 INCHES MAXIMUM IN
surface_finish32.0 MICROINCHES ALL SURFACES
hardness_rating40.0 ROCKWELL C MINIMUM AND 46.0 ROCKWELL C MAXIMUM
recess_diameter0.845 INCHES MINIMUM AND 0.855 INCHES MAXIMUM IN
outside_diameter0.552 INCHES MINIMUM AND 0.562 INCHES MAXIMUM IN
special_featuresPER ENGINEERING NOTES, MAX TEMP USEAGE 450 DEGREES
style_designatorRECESSED
surface_treatmentCADMIUM OVERALL
material_thickness0.160 INCHES MINIMUM AND 0.185 INCHES MAXIMUM IN
NSN5310-01-392-4127
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: K39781-7 · 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
•
SURFACE FINISH: 32.0 MICROINCHES ALL SURFACES
•
SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: QQ-P-416,TY 2,CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
•
HARDNESS RATING: 40.0 ROCKWELL C MINIMUM AND 46.0 ROCKWELL C MAXIMUM
•
STYLE DESIGNATOR: CONVEX
•
MATERIAL DOCUMENT AND CLASSIFICATION: MIL-S-6049 MIL SPEC 1ST MATERIAL RESPONSE OR MIL-S-6758 MIL SPEC 2ND MATERIAL RESPONSE OR MIL-S-18729 MIL SPEC 2ND MATERIAL RESPONSE OVERALL
•
OUTSIDE DIAMETER: 0.845 INCHES MINIMUM AND 0.855 INCHES MAXIMUM IN
•
MATERIAL THICKNESS: 0.160 INCHES MINIMUM AND 0.180 INCHES MAXIMUM IN
TECHNICAL CHARACTERISTICS
SURFACE FINISH32.0 MICROINCHES ALL SURFACES
SURFACE TREATMENT DOCUMENT AND CLASSIFICATIONQQ-P-416,TY 2,CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
HARDNESS RATING40.0 ROCKWELL C MINIMUM AND 46.0 ROCKWELL C MAXIMUM
STYLE DESIGNATORCONVEX
MATERIAL DOCUMENT AND CLASSIFICATIONMIL-S-6049 MIL SPEC 1ST MATERIAL RESPONSE OR MIL-S-6758 MIL SPEC 2ND MATERIAL RESPONSE OR MIL-S-18729 MIL SPEC 2ND MATERIAL RESPONSE OVERALL
OUTSIDE DIAMETER0.845 INCHES MINIMUM AND 0.855 INCHES MAXIMUM IN
MATERIAL THICKNESS0.160 INCHES MINIMUM AND 0.180 INCHES MAXIMUM IN
SPECIAL FEATURESSPHERICAL RADIUS 0.515 IN. MIN 0.535 IN. MAX,COUNTERSINK DIA 0.552 IN. MIN 0.562 IN. MAX,COUNTERSINK DEPTH 0.025 IN.,RECESS ANGLE 89 DEG MIN 91 DEG MAX IN
SURFACE TREATMENTCADMIUM AND CHROMATE OVERALL
MATERIALSTEEL COMP 8740 OR STEEL COMP 4130 OVERALL
SUBSTITUTES & CROSS-REFERENCES 2
M45595/6-05Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
MIL-W-45595/6Reference document
Same NSN cross-reference
Reference document — Identification reference
LIFECYCLE
NSN statusCancelled· U.S. Government catalog
Acquisition advice: Normally procured from the manufacturer (OEM)No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is K39781-7?
K39781-7 is a WASHER,CONVEX.
What parts can replace K39781-7?
There are 2 known substitutes for K39781-7: M45595/6-05, MIL-W-45595/6. Substitute compatibility should be verified for your specific system.
What is the NSN for K39781-7?
K39781-7 is cataloged in the U.S. Government catalog under NSN 5310-01-392-4127. 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.