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MS21281-11 — BOLT,MACHINE

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

MS21281-11: BOLT,MACHINE.

The BOLT,MACHINE is a the manufacturer industrial component. Key specifications include material: IRON ALLOY 660 OVERALL, head_style: DOUBLE HEXAGON W/HOLE, head_height: 0.365 INCHES MINIMUM AND 0.385 INCHES MAXIMUM IN, thread_class: 3A A, thread_length: 0.845 INCHES MINIMUM AND 0.948 INCHES MAXIMUM IN, surface_finish: 63.0 MICROINCHES BEARING SURFACE OF HEAD. This part is cataloged in the U.S.

Government catalog under NSN 5306-01-113-9733, 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
MS21281-11
NSN: 5306-01-113-9733
FSC: 5306 — Bolts
CAGE: 81349 — MILITARY SPECIFICATIONS PROMULGATED BY MILITARY DEPARTMENTS/AGENCIES UNDER AUTHORITY OF DEFENSE STANDARDIZATION MANUAL 4120 3-M
SPECIFICATIONS
materialIRON ALLOY 660 OVERALL
head_styleDOUBLE HEXAGON W/HOLE
head_height0.365 INCHES MINIMUM AND 0.385 INCHES MAXIMUM IN
thread_class3A A
thread_length0.845 INCHES MINIMUM AND 0.948 INCHES MAXIMUM IN
surface_finish63.0 MICROINCHES BEARING SURFACE OF HEAD
fastener_length0.928 INCHES MINIMUM AND 0.948 INCHES MAXIMUM IN
hardness_rating24.0 ROCKWELL C MINIMUM AND 35.0 ROCKWELL C MAXIMUM OVERALL
thread_directionRIGHT-HAND
features_providedFINISHED HEAD
width_between_flats0.367 INCHES MINIMUM AND 0.376 INCHES MAXIMUM IN
nominal_thread_diameter0.312 INCHES IN
NSN5306-01-113-9733
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: MS21281-11 · 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
•
EXTENDED WASHER THICKNESS: 0.070 INCHES MINIMUM AND 0.080 INCHES MAXIMUM IN
•
HEAD HEIGHT: 0.365 INCHES MINIMUM AND 0.385 INCHES MAXIMUM IN
•
FASTENER LENGTH: 0.928 INCHES MINIMUM AND 0.948 INCHES MAXIMUM IN
•
EXTENDED WASHER DIAMETER: 0.490 INCHES MINIMUM AND 0.510 INCHES MAXIMUM IN
•
THREAD LENGTH: 0.845 INCHES MINIMUM AND 0.948 INCHES MAXIMUM IN
TECHNICAL CHARACTERISTICS
SURFACE FINISH32.0 MICROINCHES THREADS
SURFACE FINISH63.0 MICROINCHES GRIP
SURFACE FINISH63.0 MICROINCHES BEARING SURFACE OF HEAD
EXTENDED WASHER THICKNESS0.070 INCHES MINIMUM AND 0.080 INCHES MAXIMUM IN
HEAD HEIGHT0.365 INCHES MINIMUM AND 0.385 INCHES MAXIMUM IN
FASTENER LENGTH0.928 INCHES MINIMUM AND 0.948 INCHES MAXIMUM IN
EXTENDED WASHER DIAMETER0.490 INCHES MINIMUM AND 0.510 INCHES MAXIMUM IN
THREAD LENGTH0.845 INCHES MINIMUM AND 0.948 INCHES MAXIMUM IN
HARDNESS RATING24.0 ROCKWELL C MINIMUM AND 35.0 ROCKWELL C MAXIMUM OVERALL
MATERIAL DOCUMENT AND CLASSIFICATIONAMS 5732 ASSN STD SINGLE MATERIAL RESPONSE OVERALL
OTHER ITEMS IN FSC 5306 — Bolts
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5306-00-001-1276 5306-00-001-1949 5306-00-001-1988 5306-00-001-1989 5306-00-001-1990 5306-00-001-1991 5306-00-001-1993 5306-00-001-2017
SUBSTITUTES & CROSS-REFERENCES 2
HT2804 REF.A2H 6630Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
26000465Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
LIFECYCLE
NSN statusActive· U.S. Government catalog
No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is MS21281-11?
MS21281-11 is a BOLT,MACHINE.
What parts can replace MS21281-11?
There are 2 known substitutes for MS21281-11: HT2804 REF.A2H 6630, 26000465. Substitute compatibility should be verified for your specific system.
What is the NSN for MS21281-11?
MS21281-11 is cataloged in the U.S. Government catalog under NSN 5306-01-113-9733. 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.