PartsTable
Technical Data Sheet
Download PDF

MS9491-20 — BOLT,MACHINE

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

MS9491-20: BOLT,MACHINE.

The BOLT,MACHINE is a the manufacturer industrial component. Key specifications include material: IRON ALLOY 660 OVERALL, head_style: HEXAGON, head_height: 0.188 INCHES NOMINAL IN, thread_class: 3A A, thread_length: 0.875 INCHES MINIMUM AND 0.935 INCHES MAXIMUM IN, fastener_length: 1.500 INCHES NOMINAL IN. This part is cataloged in the U.S.

Government catalog under NSN 5306-01-009-6631, 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
MS9491-20
NSN: 5306-01-009-6631
NIINs: 010096631, 014974197
FSC: 5306 — Bolts
CAGE: 96906 — MILITARY STANDARDS PROMULGATED BY MILITARY DEPARTMENTS UNDER AUTHORITY OF DEFENSE STANDARDIZATION MANUAL 4120 3-M
SPECIFICATIONS
materialIRON ALLOY 660 OVERALL
head_styleHEXAGON
head_height0.188 INCHES NOMINAL IN
thread_class3A A
thread_length0.875 INCHES MINIMUM AND 0.935 INCHES MAXIMUM IN
fastener_length1.500 INCHES NOMINAL IN
thread_directionRIGHT-HAND
width_between_flats0.492 INCHES MINIMUM AND 0.502 INCHES MAXIMUM IN
nominal_thread_diameter0.312 INCHES IN
thread_quantity_per_inch24
thread_series_designatorUNIFIED NATIONAL JOINT FINE (UNJF)
material_document_and_classificationAMS 5731 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
NSN5306-01-009-6631
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: MS9491-20 · 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
•
SURFACE FINISH: 32.0 MICROINCHES THREADS
•
HEAD HEIGHT: 0.188 INCHES NOMINAL IN
•
FASTENER LENGTH: 1.490 INCHES MINIMUM AND 1.510 INCHES MAXIMUM IN
•
THREAD LENGTH: 0.865 INCHES MINIMUM AND 0.945 INCHES MAXIMUM IN
•
HARDNESS RATING: 24.0 ROCKWELL C MINIMUM AND 35.0 ROCKWELL C MAXIMUM OVERALL
•
MATERIAL DOCUMENT AND CLASSIFICATION: AMS 5731 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
TECHNICAL CHARACTERISTICS
SURFACE FINISH32.0 MICROINCHES THREADS
SURFACE FINISH32.0 MICROINCHES GRIP
SURFACE FINISH32.0 MICROINCHES BEARING SURFACE OF HEAD
HEAD HEIGHT0.188 INCHES NOMINAL IN
FASTENER LENGTH1.490 INCHES MINIMUM AND 1.510 INCHES MAXIMUM IN
THREAD LENGTH0.865 INCHES MINIMUM AND 0.945 INCHES MAXIMUM IN
HARDNESS RATING24.0 ROCKWELL C MINIMUM AND 35.0 ROCKWELL C MAXIMUM OVERALL
MATERIAL DOCUMENT AND CLASSIFICATIONAMS 5731 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
NOMINAL THREAD DIAMETER0.312 INCHES IN
FEATURES PROVIDEDFINISHED HEAD
SUBSTITUTES & CROSS-REFERENCES 1
5306PL1496495Reference document
Same NSN cross-reference
Reference document — Informative reference only
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Terminal item — no further procurement; issued until stock is exhaustedNo demilitarization required
Ready to buy MS9491-20?
Compare prices from verified sellers on eBay
Buy on eBay →
As an eBay Partner, PartsTable may earn a commission. Your price is not affected.
FREQUENTLY ASKED QUESTIONS
What is MS9491-20?
MS9491-20 is a BOLT,MACHINE.
What parts can replace MS9491-20?
There is 1 known substitute for MS9491-20: 5306PL1496495. Substitute compatibility should be verified for your specific system.
What is the NSN for MS9491-20?
MS9491-20 is cataloged in the U.S. Government catalog under NSN 5306-01-009-6631. This indicates validated use in U.S. government and defense supply chains.
Community Feedback
Leave a Comment
Comments are reviewed before appearing. You will receive an email to verify before your comment appears.

Request a Quote — MS9491-20

✓ 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.