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MILB857 ✓ 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,HEXAGON HEAD is a the manufacturer industrial component. Key specifications include material: NICKEL ALLOY 400 OVERALL, head_style: HEXAGON, head_height: 0.302 INCHES MINIMUM AND 0.323 INCHES MAXIMUM IN, thread_class: 2A A, thread_length: 0.984 INCHES NOMINAL IN, fastener_length: 3.000 INCHES NOMINAL IN. This product is currently in active production with full OEM support.

This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 5305-00-009-9157, 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
MILB857
NSN: 5305-00-009-9157
FSC: 5305
CAGE: 81349 — MILITARY SPECIFICATIONS PROMULGATED BY MILITARY DEPARTMENTS/AGENCIES UNDER AUTHORITY OF DEFENSE STANDARDIZATION MANUAL 4120 3-M
SPECIFICATIONS
materialNICKEL ALLOY 400 OVERALL
head_styleHEXAGON
head_height0.302 INCHES MINIMUM AND 0.323 INCHES MAXIMUM IN
thread_class2A A
thread_length0.984 INCHES NOMINAL IN
fastener_length3.000 INCHES NOMINAL IN
hardness_rating80.0 ROCKWELL B MINIMUM OVERALL
thread_directionRIGHT-HAND
width_between_flats1.100 INCHES MINIMUM AND 1.125 INCHES MAXIMUM IN
minimum_yield_strength40000 MEGAPASCALS
end_item_identificationHATCH COVER, LOCKING RING TYPE
nominal_thread_diameter0.750 INCHES IN
NSN5305-00-009-9157
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: MILB857 · 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
•
WIDTH BETWEEN FLATS: 1.100 INCHES MINIMUM AND 1.125 INCHES MAXIMUM IN
•
MATERIAL: NICKEL ALLOY 400 OVERALL
•
TEST DATA DOCUMENT: 81349-MIL-P-23199 SPECIFICATION (INCLUDES ENGINEERING TYPE BULLETINS, BROCHURES,ETC., THAT REFLECT SPECIFICATION TYPE DATA IN SPECIFICATION FORMAT; EXCLUDES COMMERCIAL CATALOGS, INDUSTRY DIRECTORIES, AND SIMILAR TRADE PUBLICATIONS, REFLECTING GENERAL TYPE DATA ON CERTAIN ENVIRONMENTAL AND PERFORMANCE REQUIREMENTS AND TEST CONDITIONS THAT ARE SHOWN AS "TYPICAL", "AVERAGE", "NOMINAL", ETC.).
•
NONDEFINITIVE SPEC/STD DATA: 3 TYPE
•
SPECIAL TEST FEATURES: SPECIAL QUALITY CONTROL TESTING
•
THREAD SERIES DESIGNATOR: UNIFIED NATIONAL COARSE (UNC)
•
MATERIAL DOCUMENT AND CLASSIFICATION: QQ-N-281,CLASS A FED SPEC SINGLE MATERIAL RESPONSE OVERALL
•
REFERENCE NUMBER DIFFERENTIATING CHARACTERISTICS: MATERIAL MUST CONFORM TO SHIPS PARTS CONTROL CENTER SPECIAL QUALITY CONTROL PROVISIONS
TECHNICAL CHARACTERISTICS (FLIS)
WIDTH BETWEEN FLATS1.100 INCHES MINIMUM AND 1.125 INCHES MAXIMUM IN
MATERIALNICKEL ALLOY 400 OVERALL
TEST DATA DOCUMENT81349-MIL-P-23199 SPECIFICATION (INCLUDES ENGINEERING TYPE BULLETINS, BROCHURES,ETC., THAT REFLECT SPECIFICATION TYPE DATA IN SPECIFICATION FORMAT; EXCLUDES COMMERCIAL CATALOGS, INDUSTRY DIRECTORIES, AND SIMILAR TRADE PUBLICATIONS, REFLECTING GENERAL TYPE DATA ON CERTAIN ENVIRONMENTAL AND PERFORMANCE REQUIREMENTS AND TEST CONDITIONS THAT ARE SHOWN AS "TYPICAL", "AVERAGE", "NOMINAL", ETC.).
NONDEFINITIVE SPEC/STD DATA3 TYPE
SPECIAL TEST FEATURESSPECIAL QUALITY CONTROL TESTING
THREAD SERIES DESIGNATORUNIFIED NATIONAL COARSE (UNC)
MATERIAL DOCUMENT AND CLASSIFICATIONQQ-N-281,CLASS A FED SPEC SINGLE MATERIAL RESPONSE OVERALL
REFERENCE NUMBER DIFFERENTIATING CHARACTERISTICSMATERIAL MUST CONFORM TO SHIPS PARTS CONTROL CENTER SPECIAL QUALITY CONTROL PROVISIONS
THREAD CLASS2A A
HEAD HEIGHT0.455 INCHES MINIMUM AND 0.483 INCHES MAXIMUM IN
VERIFIED SUBSTITUTES & CROSS-REFERENCES 2
5305PL1732615Interchangeable
Same NIIN cross-reference
interchangeable
2620-709X4PC154Interchangeable
Same NIIN cross-reference
interchangeable
LIFECYCLE
StatusACTIVE
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is MILB857?
MILB857 is a SCREW,CAP,HEXAGON HEAD.
What parts can replace MILB857?
There are 2 known substitutes for MILB857: 5305PL1732615, 2620-709X4PC154. Substitute compatibility should be verified for your specific system.
What is the NSN for MILB857?
MILB857 is cataloged in the Federal Logistics Information System (FLIS) under NSN 5305-00-009-9157. 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: July 2026