PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

MS51021-56Setscrew

National Aerospace Standards Committee Aerospace Industries Association of America Inc Not for Rfq or Solicitation Use · NSN 5305-00-817-6139 · FSC 5305 · No Item Name Available
Verified by PartsTable
NSN 5305-00-817-6139 — this item is cataloged by the U.S. Government under National Stock Number 5305-00-817-6139. Primary manufacturer part number: MS51021-56.
Features
  • Setscrew — FSC 5305
  • Nominal Thread Diameter: 0.250 INCHES IN
  • Thread Quantity Per Inch: 20
  • Thread Series Designator: UNIFIED NATIONAL COARSE (UNC)
  • Surface Treatment Document and Classification: QQ-P-35 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
  • Material: STEEL COMP 302 OR STEEL COMP 303 OR STEEL COMP 304 OR STEEL COMP 316 OVERALL
  • Material Document and Classification: 66 FED STD ALL MATERIAL RESPONSES OVERALL
  • Surface Treatment: PASSIVATE OVERALL
Applications
  • Applications requiring Steel Comp 302 or Steel Comp 303 or Steel Comp 304 or Steel Comp 316 Overall construction
General Description

The Setscrew, cataloged under National Stock Number 5305-00-817-6139, is classified within Federal Supply Class 5305 (No Item Name Available) of the Hardware and Abrasives group. The primary manufacturer of record is National Aerospace Standards Committee Aerospace Industries Association of America Inc Not for Rfq or Solicitation Use. Government technical data includes 16 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 10 commercial cross-references from 9 manufacturers, enabling identification through both NSN and commercial part number lookups. 11 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Cancelled.

Technical Specifications
ParameterValue
NSN5305-00-817-6139
Primary Part NumberMS51021-56
Item NameSetscrew
FSC / FSG5305 / 53 — No Item Name Available
ManufacturerNational Aerospace Standards Committee Aerospace Industries Association of America Inc Not for Rfq or Solicitation Use
StatusCANCELLED
Nominal Thread Diameter0.250 INCHES IN
Thread Quantity Per Inch20
Thread Series DesignatorUNIFIED NATIONAL COARSE (UNC)
Surface Treatment Document and ClassificationQQ-P-35 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
MaterialSTEEL COMP 302 OR STEEL COMP 303 OR STEEL COMP 304 OR STEEL COMP 316 OVERALL
Material Document and Classification66 FED STD ALL MATERIAL RESPONSES OVERALL
Surface TreatmentPASSIVATE OVERALL
Nondefinitive Spec/std Data1 TYPE AND 4 STYLE
Width Across Flats0.125 INCHES NOMINAL IN
Internal Drive StyleHEXAGON
Head StyleHEADLESS (SETSCREW)
Fastener Length0.250 INCHES NOMINAL IN
Point StyleCUP
Thread DirectionRIGHT-HAND
Thread Class3A A
Thread Length0.250 INCHES MAXIMUM IN
Lifecycle & Compliance
Acquisition StatusCANCELLED
HAZMATNo
Verified Substitutes 11
5331-00-171-8266PRP902-53-718-40 INTERCHANGEABLE
O-Ring
Parker Hannifin Corporation Div O-Ring Division
5305-00-484-69788344 INTERCHANGEABLE
Setscrew
Triumph Engine Control Systems Llc
4720-00-580-74708380781 INTERCHANGEABLE
Hose Assembly,nonmetallic
U S Army Tank Automotive Command Amsta-Im-Mm
5310-00-591-31728344 INTERCHANGEABLE
Nut,self-Locking,cone Seat,hexag
Eaton Corp Transmission Div
5905-00-846-9289 INTERCHANGEABLE
Resistor,variable,wire Wound,non
4940-01-285-5676 INTERCHANGEABLE
Tablemat,static Eliminator
5340-01-341-5213 INTERCHANGEABLE
Plate,mounting
5340-01-417-2951 INTERCHANGEABLE
Standoff,threaded,spacing
5136-01-431-64938344 INTERCHANGEABLE
Tap,thread Cutting
Stanley Tools Div of Stanley Works
5305-01-432-2140 INTERCHANGEABLE
Screw,machine
Cross-Reference Index
Part NumberManufacturer
20-140C4 Hf Group Inc Dba Hf Group Inc (USA)
003-07941-056 Northrop Grumman Systems Corporation Dba Northrop Grumman Systems Corp Div Multiple (USA)
MS51021-56 Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M
MS51021-56 PRIMARY National Aerospace Standards Committee Aerospace Industries Association of America Inc Not for Rfq or Solicitation Use (USA)
H81-1/4-20 X 4 Flowserve Corp Dba Automax Actuators Div Flowserve Us Company (USA)
FF-S-200 Federal Specifications Promulgated by General Services Administration Washington DC (USA)
01-435-0403-4 ITEM 143 Flowserve Corp Dba Automax Actuators Div Flowserve Us Company (USA)
6634436-001 Naval Sea Systems Command (USA)
83-44 Cnh Industrial America Llc Dba Cnh America (USA)
5305PL1336637 Jednolity Indeks Materialowy - Uniform Material Index (POL)
Related Parts
5331-00-171-8266INTERCHANGEABLE
O-RING
PRP902-53-718-40
5305-00-484-6978INTERCHANGEABLE
SETSCREW
8344
4720-00-580-7470INTERCHANGEABLE
HOSE ASSEMBLY,NONMETALLIC
8380781
5310-00-591-3172INTERCHANGEABLE
NUT,SELF-LOCKING,CONE SEAT,HEXAG
8344
5905-00-846-9289INTERCHANGEABLE
RESISTOR,VARIABLE,WIRE WOUND,NON
4940-01-285-5676INTERCHANGEABLE
TABLEMAT,STATIC ELIMINATOR
5340-01-341-5213INTERCHANGEABLE
PLATE,MOUNTING
5340-01-417-2951INTERCHANGEABLE
STANDOFF,THREADED,SPACING
5136-01-431-6493INTERCHANGEABLE
TAP,THREAD CUTTING
8344
5305-01-432-2140INTERCHANGEABLE
SCREW,MACHINE
5305-01-463-1046INTERCHANGEABLE
SCREW,MACHINE
741279-A

Frequently Asked Questions

What is NSN 5305-00-817-6139?

NSN 5305-00-817-6139 is a Setscrew, manufactured by National Aerospace Standards Committee Aerospace Industries Association of America Inc Not for Rfq or Solicitation Use, classified under FSC 5305 (No Item Name Available). Status: cancelled.

What are the part numbers for NSN 5305-00-817-6139?

NSN 5305-00-817-6139 has 10 cross-referenced part numbers: 20-140C4 (Hf Group Inc Dba Hf Group Inc), 003-07941-056 (Northrop Grumman Systems Corporation Dba Northrop Grumman Systems Corp Div Multiple), MS51021-56 (Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M), MS51021-56 (National Aerospace Standards Committee Aerospace Industries Association of America Inc Not for Rfq or Solicitation Use), H81-1/4-20 X 4 (Flowserve Corp Dba Automax Actuators Div Flowserve Us Company) and 5 more.

What NSN replaces 5305-00-817-6139?

There are 11 known substitutes for 5305-00-817-6139: 5331-00-171-8266, 5305-00-484-6978, 4720-00-580-7470 and 8 more. Verify interchangeability with system specifications before substitution.

What are the specifications of MS51021-56?

Key specifications for MS51021-56: Nominal Thread Diameter: 0.250 INCHES IN; Thread Quantity Per Inch: 20; Thread Series Designator: UNIFIED NATIONAL COARSE (UNC); Surface Treatment Document and Classification: QQ-P-35 FED SPEC SINGLE TREATMENT RESPONSE OVERALL. 16 total characteristics are documented in the Federal Logistics Information System.

Is NSN 5305-00-817-6139 still in active supply?

NSN 5305-00-817-6139 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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