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21-1538 — SCREW,MACHINE

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

21-1538: SCREW,MACHINE.

The SCREW,MACHINE is a the manufacturer industrial component. Key specifications include head_style: FLAT COUNTERSUNK, thread_class: 2A A, head_diameter: 0.249 INCHES MINIMUM AND 0.279 INCHES MAXIMUM IN, thread_length: 0.250 INCHES MINIMUM AND 0.312 INCHES MAXIMUM IN, screw_material: STEEL COMP 1010, fastener_length: 0.281 INCHES MINIMUM AND 0.312 INCHES MAXIMUM IN. This part is cataloged in the U.S.

Government catalog under NSN 5305-00-006-9249, 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
21-1538
NSN: 5305-00-006-9249
NIINs: 000069249, 001443949
FSC: 5305 — Screws
CAGE: 66935 — JOHNSON CONTROLS NAVY SYSTEMS, LLC (USA)
SPECIFICATIONS
head_styleFLAT COUNTERSUNK
thread_class2A A
head_diameter0.249 INCHES MINIMUM AND 0.279 INCHES MAXIMUM IN
thread_length0.250 INCHES MINIMUM AND 0.312 INCHES MAXIMUM IN
screw_materialSTEEL COMP 1010
fastener_length0.281 INCHES MINIMUM AND 0.312 INCHES MAXIMUM IN
thread_directionRIGHT-HAND
countersink_angle99.0 DEGREES MINIMUM AND 101.0 DEGREES MAXIMUM
internal_drive_styleCROSS RECESS TYPE 1
nominal_thread_diameter0.138 INCHES IN
screw_surface_treatmentCADMIUM
minimum_tensile_strength55 POUNDS PER SQUARE INCH LBS
NSN5305-00-006-9249
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: 21-1538 · 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
•
GENERAL CHARACTERISTICS ITEM DESCRIPTION: STEEL,UNCOATED,7/16-14 UNC 2A THD SIZE,1.250 IN.LG A
TECHNICAL CHARACTERISTICS
GENERAL CHARACTERISTICS ITEM DESCRIPTIONSTEEL,UNCOATED,7/16-14 UNC 2A THD SIZE,1.250 IN.LG A
SUBSTITUTES & CROSS-REFERENCES

No substitute or cross-reference records for this part.

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 21-1538?
21-1538 is a SCREW,MACHINE.
What is the NSN for 21-1538?
21-1538 is cataloged in the U.S. Government catalog under NSN 5305-00-006-9249. 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.