PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

S643Screw,cap,socket Head

Bae Systems Land & Armaments L.p. · NSN 5305-00-639-8085 · FSC 5305 · No Item Name Available
Verified by PartsTable
NSN 5305-00-639-8085 — this item is cataloged by the U.S. Government under National Stock Number 5305-00-639-8085. Primary manufacturer part number: S643.
Features
  • Screw,cap,socket Head — FSC 5305
  • Head Diameter: 0.367 INCHES MINIMUM AND 0.375 INCHES MAXIMUM IN
  • Minimum Yield Strength: 140000 POUNDS PER SQUARE INCH LBS
  • Thread Direction: RIGHT-HAND
  • Thread Series Designator: UNIFIED NATIONAL COARSE (UNC)
  • Thread Quantity Per Inch: 20
  • Nondefinitive Spec/std Data: 1 TYPE AND 11 STYLE
  • Material Document and Classification: QQ-S-624 FED SPEC ALL MATERIAL RESPONSES OVERALL
Applications
  • Structural fastening and assembly
  • Equipment mounting
  • Panel and housing attachment
  • Applications requiring Steel Comp 2340 or Steel Comp 3135 or Steel Comp 4037 or Steel Comp 4137 or Steel Comp 4140 or Steel Comp 4340 or Steel Comp 8630 or Steel Comp 8740 Overall construction
General Description

The Screw,cap,socket Head, cataloged under National Stock Number 5305-00-639-8085, is classified within Federal Supply Class 5305 (No Item Name Available) of the Hardware and Abrasives group. The primary manufacturer of record is Bae Systems Land & Armaments L.p.. Government technical data includes 18 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 2 commercial cross-references from 2 manufacturers, enabling identification through both NSN and commercial part number lookups. 9 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Cancelled.

Technical Specifications
ParameterValue
NSN5305-00-639-8085
Primary Part NumberS643
Item NameScrew,cap,socket Head
FSC / FSG5305 / 53 — No Item Name Available
ManufacturerBae Systems Land & Armaments L.p.
StatusCANCELLED
Head Diameter0.367 INCHES MINIMUM AND 0.375 INCHES MAXIMUM IN
Minimum Yield Strength140000 POUNDS PER SQUARE INCH LBS
Thread DirectionRIGHT-HAND
Thread Series DesignatorUNIFIED NATIONAL COARSE (UNC)
Thread Quantity Per Inch20
Nondefinitive Spec/std Data1 TYPE AND 11 STYLE
Material Document and ClassificationQQ-S-624 FED SPEC ALL MATERIAL RESPONSES OVERALL
Head StyleFLAT CHAMFER
Nominal Thread Diameter0.250 INCHES IN
Internal Drive StyleHEXAGON
Surface TreatmentCADMIUM OR ZINC OVERALL
MaterialSTEEL COMP 2340 OR STEEL COMP 3135 OR STEEL COMP 4037 OR STEEL COMP 4137 OR STEEL COMP 4140 OR STEEL COMP 4340 OR STEEL COMP 8630 OR STEEL COMP 8740 OVERALL
Head Height0.244 INCHES MINIMUM AND 0.250 INCHES MAXIMUM IN
Hardness Rating36.0 ROCKWELL C MINIMUM AND 43.0 ROCKWELL C MAXIMUM OVERALL
Fastener Length2.750 INCHES NOMINAL IN
Thread Class3A A
Width Across Flats0.187 INCHES MINIMUM AND 0.189 INCHES MAXIMUM IN
Thread Length1.375 INCHES NOMINAL IN
Lifecycle & Compliance
Acquisition StatusCANCELLED
HAZMATNo
Verified Substitutes 9
4310-00-060-4586 INTERCHANGEABLE
Ring,piston
5940-00-115-2676MS20659-143 INTERCHANGEABLE
Terminal,lug
Sae International Dba Sae International
3940-00-235-84534080517 INTERCHANGEABLE
Link,hoisting
Textron Aviation Inc
5365-01-036-7243 INTERCHANGEABLE
Ring,connecting,round
5365-01-056-834111153730 INTERCHANGEABLE
Ring,connecting,round
Us Army Aviation and Missile Command
5365-01-227-9457521-4788614 ITEM 114 INTERCHANGEABLE
Ring,connecting,round
Naval Ship Systems Command
4730-01-251-221913228E2595-67 INTERCHANGEABLE
Plug,pipe
Cecom Lr Center
5360-01-481-9878S-643 INTERCHANGEABLE
Spring,helical,extension
Matthew Warren, Inc. Dba Century Spring Corp. Div Century Spring Corp.
5325-01-557-9361S643 INTERCHANGEABLE
Ring,retaining
Palfinger Marine Usa, Llc
Cross-Reference Index
Part NumberManufacturer
S643 PRIMARY Bae Systems Land & Armaments L.p. (USA)
587452 Army Weapons Command Attn Amswe-Ree-S (USA)
Related Parts
4310-00-060-4586INTERCHANGEABLE
RING,PISTON
5940-00-115-2676INTERCHANGEABLE
TERMINAL,LUG
MS20659-143
3940-00-235-8453INTERCHANGEABLE
LINK,HOISTING
4080517
5365-01-036-7243INTERCHANGEABLE
RING,CONNECTING,ROUND
5365-01-056-8341INTERCHANGEABLE
RING,CONNECTING,ROUND
11153730
5365-01-227-9457INTERCHANGEABLE
RING,CONNECTING,ROUND
521-4788614 ITEM 114
4730-01-251-2219INTERCHANGEABLE
PLUG,PIPE
13228E2595-67
5360-01-481-9878INTERCHANGEABLE
SPRING,HELICAL,EXTENSION
S-643
5325-01-557-9361INTERCHANGEABLE
RING,RETAINING
S643

Frequently Asked Questions

What is NSN 5305-00-639-8085?

NSN 5305-00-639-8085 is a Screw,cap,socket Head, manufactured by Bae Systems Land & Armaments L.p., classified under FSC 5305 (No Item Name Available). Status: cancelled.

What are the part numbers for NSN 5305-00-639-8085?

NSN 5305-00-639-8085 has 2 cross-referenced part numbers: S643 (Bae Systems Land & Armaments L.p.), 587452 (Army Weapons Command Attn Amswe-Ree-S).

What NSN replaces 5305-00-639-8085?

There are 9 known substitutes for 5305-00-639-8085: 4310-00-060-4586, 5940-00-115-2676, 3940-00-235-8453 and 6 more. Verify interchangeability with system specifications before substitution.

What are the specifications of S643?

Key specifications for S643: Head Diameter: 0.367 INCHES MINIMUM AND 0.375 INCHES MAXIMUM IN; Minimum Yield Strength: 140000 POUNDS PER SQUARE INCH LBS; Thread Direction: RIGHT-HAND; Thread Series Designator: UNIFIED NATIONAL COARSE (UNC). 18 total characteristics are documented in the Federal Logistics Information System.

Is NSN 5305-00-639-8085 still in active supply?

NSN 5305-00-639-8085 is currently cancelled. Check with the Defense Logistics Agency for current availability and authorized substitutes.

Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
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