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1M644 — SCREW,CAP,HEXAGON HEAD

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

1M644: SCREW,CAP,HEXAGON HEAD.

The SCREW,CAP,HEXAGON HEAD is a the manufacturer industrial component. Key specifications include head_style: HEXAGON, head_height: 0.270 INCHES MINIMUM AND 0.295 INCHES MAXIMUM IN, thread_class: 2A A, thread_length: 1.625 INCHES NOMINAL IN, fastener_length: 2.250 INCHES NOMINAL IN, width_between_flats: 0.551 INCHES MINIMUM AND 0.562 INCHES MAXIMUM IN. This part is cataloged in the U.S.

Government catalog under NSN 5305-00-253-7630, 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
1M644
NSN: 5305-00-253-7630
FSC: 5305 — Screws
CAGE: 11083 — CATERPILLAR INC DIV CATERPILLAR DEFENSE (USA)
SPECIFICATIONS
head_styleHEXAGON
head_height0.270 INCHES MINIMUM AND 0.295 INCHES MAXIMUM IN
thread_class2A A
thread_length1.625 INCHES NOMINAL IN
fastener_length2.250 INCHES NOMINAL IN
width_between_flats0.551 INCHES MINIMUM AND 0.562 INCHES MAXIMUM IN
end_item_identificationLOGISTICS SUPPORT VESSEL
NSN5305-00-253-7630
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: 1M644 · 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
•
HEAD HEIGHT: 0.270 INCHES MINIMUM AND 0.295 INCHES MAXIMUM IN
•
FASTENER LENGTH: 2.250 INCHES NOMINAL IN
•
THREAD LENGTH: 1.625 INCHES NOMINAL IN
•
HEAD STYLE: HEXAGON
•
WIDTH BETWEEN FLATS: 0.551 INCHES MINIMUM AND 0.562 INCHES MAXIMUM IN
•
THREAD CLASS: 2A A
TECHNICAL CHARACTERISTICS
HEAD HEIGHT0.270 INCHES MINIMUM AND 0.295 INCHES MAXIMUM IN
FASTENER LENGTH2.250 INCHES NOMINAL IN
THREAD LENGTH1.625 INCHES NOMINAL IN
HEAD STYLEHEXAGON
WIDTH BETWEEN FLATS0.551 INCHES MINIMUM AND 0.562 INCHES MAXIMUM IN
THREAD CLASS2A A
END ITEM IDENTIFICATIONLOGISTICS SUPPORT VESSEL
OTHER ITEMS IN FSC 5305 — Screws
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5305-00-001-5016 5305-00-001-9160 5305-00-001-9629 5305-00-001-9742 5305-00-001-9768 5305-00-003-4306 5305-00-003-6694 5305-00-003-6753
SUBSTITUTES & CROSS-REFERENCES 2
17KP397Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
1M0644Same NSN cross-reference
Same NSN cross-reference
Also cataloged under this NSN
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 1M644?
1M644 is a SCREW,CAP,HEXAGON HEAD.
What parts can replace 1M644?
There are 2 known substitutes for 1M644: 17KP397, 1M0644. Substitute compatibility should be verified for your specific system.
What is the NSN for 1M644?
1M644 is cataloged in the U.S. Government catalog under NSN 5305-00-253-7630. 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.