PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

B18.3Key,socket Head Screw

The American Society of Mechanical Engineers · NSN 5120-00-781-8977 · FSC 5120 · No Item Name Available
Verified by PartsTable
NSN 5120-00-781-8977 — this item is cataloged by the U.S. Government under National Stock Number 5120-00-781-8977. Primary manufacturer part number: B18.3.
Features
  • Key,socket Head Screw — FSC 5120
  • Wrenching Surface Flute Quantity: 4
  • Style Designator: L-HANDLE
  • Wrenching Surface Shape: SPLINE BOTH ENDS EXTERNAL
  • Wrenching Surface Size: 0.076 INCHES NOMINAL BOTH ENDS IN
  • Specification/standard Data: 05047-ASME B18.3 PROFESSIONAL/INDUSTRIAL ASSOCIATION STANDARD
  • Long Arm Length: 1.656 INCHES MINIMUM AND 1.844 INCHES MAXIMUM IN
  • Features Provided: SHORT SERIES
Applications
  • Structural fastening and assembly
  • Equipment mounting
  • Panel and housing attachment
  • Applications requiring Steel Overall construction
General Description

The Key,socket Head Screw, cataloged under National Stock Number 5120-00-781-8977, is classified within Federal Supply Class 5120 (No Item Name Available) of the Hand Tools group. The primary manufacturer of record is The American Society of Mechanical Engineers. Government technical data includes 9 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 18 commercial cross-references from 14 manufacturers, enabling identification through both NSN and commercial part number lookups. 12 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Cancelled.

Technical Specifications
ParameterValue
NSN5120-00-781-8977
Primary Part NumberB18.3
Item NameKey,socket Head Screw
FSC / FSG5120 / 51 — No Item Name Available
ManufacturerThe American Society of Mechanical Engineers
StatusCANCELLED
Wrenching Surface Flute Quantity4
Style DesignatorL-HANDLE
Wrenching Surface ShapeSPLINE BOTH ENDS EXTERNAL
Wrenching Surface Size0.076 INCHES NOMINAL BOTH ENDS IN
Specification/standard Data05047-ASME B18.3 PROFESSIONAL/INDUSTRIAL ASSOCIATION STANDARD
Long Arm Length1.656 INCHES MINIMUM AND 1.844 INCHES MAXIMUM IN
Features ProvidedSHORT SERIES
MaterialSTEEL OVERALL
Short Arm Length0.469 INCHES MINIMUM AND 0.656 INCHES MAXIMUM IN
Lifecycle & Compliance
Acquisition StatusCANCELLED
HAZMATNo
Verified Substitutes 12
6150-00-214-2682119032 INTERCHANGEABLE
Housing,electrical Rotating Equi
Schwitzer Engine Components a Household Intl Co
5120-00-224-2482 INTERCHANGEABLE
Key,socket Head Screw
5120-00-224-2496 INTERCHANGEABLE
Key,socket Head Screw
5120-00-277-1724 INTERCHANGEABLE
Key,socket Head Screw
5120-00-288-90855120-00-288-9085 INTERCHANGEABLE
Key,socket Head Screw
General Services Administration Federal Supply Service
5120-00-293-0195 INTERCHANGEABLE
Key,socket Head Screw
2240-00-367-3470MS6A INTERCHANGEABLE
Pawl Lever Arm
Ohio Industries Inc
5120-00-529-2553 INTERCHANGEABLE
Key Set,socket Head Screw
5120-00-832-6216 INTERCHANGEABLE
Key,socket Head Screw
5120-00-893-5686 INTERCHANGEABLE
Key Set,socket Head Screw
Cross-Reference Index
Part NumberManufacturer
B18.3 The American Society of Mechanical Engineers (USA)
S0764 Bristol Babcock Inc Instruments-Systems Div Sub of Babcock Intl Inc (USA)
A-A-2925 TY2 General Services Administration Federal Supply Service (USA)
S-076-4 Mahalo Industries Inc Dba Bristol Wrench Co. (USA)
A18223-3 Honeywell International Inc Dba Honeywell (USA)
MS6A Sna Germany Gmbh (DEU)
A-A-2925 Federal Commercial Item Description Promulgated by General Services Administration Washington DC (USA)
7871267P1 Lockheed Martin Corporation Div Rms (USA)
GGG-K-275 TY2CL1 General Services Administration Federal Supply Service (USA)
119032 Northrop Grumman Systems Corporation Dba Northrop Grumman Systems Corp (USA)
MS6 Sna Germany Gmbh (DEU)
024-9730-00 Rockwell Collins, Inc. Dba Collins Aerospace Government Systems Div Collins Aerospace - Government Systems (USA)
024-9730-000 Rockwell Collins, Inc. Dba Collins Aerospace Government Systems Div Collins Aerospace - Government Systems (USA)
135A1013B Cosmos Industries Inc (USA)
S-076-4 See-Lect Industrial Equipment Co. Inc. Dba See Lect Industrl Equip (USA)
994900-5 Raytheon Company Dba Raytheon (USA)
GGG-K-275 Federal Specifications Promulgated by General Services Administration Washington DC (USA)
A-A-2473 Federal Commercial Item Description Promulgated by General Services Administration Washington DC (USA)
Related Parts
6150-00-214-2682INTERCHANGEABLE
HOUSING,ELECTRICAL ROTATING EQUI
119032
5120-00-224-2482INTERCHANGEABLE
KEY,SOCKET HEAD SCREW
5120-00-224-2496INTERCHANGEABLE
KEY,SOCKET HEAD SCREW
5120-00-277-1724INTERCHANGEABLE
KEY,SOCKET HEAD SCREW
5120-00-288-9085INTERCHANGEABLE
KEY,SOCKET HEAD SCREW
5120-00-288-9085
5120-00-293-0195INTERCHANGEABLE
KEY,SOCKET HEAD SCREW
2240-00-367-3470INTERCHANGEABLE
PAWL LEVER ARM
MS6A
5120-00-529-2553INTERCHANGEABLE
KEY SET,SOCKET HEAD SCREW
5120-00-832-6216INTERCHANGEABLE
KEY,SOCKET HEAD SCREW
5120-00-893-5686INTERCHANGEABLE
KEY SET,SOCKET HEAD SCREW
5120-00-970-8947INTERCHANGEABLE
KEY SET,SOCKET HEAD SCREW
8135-01-015-4139INTERCHANGEABLE
WRAP,PLASTIC FILM

Frequently Asked Questions

What is NSN 5120-00-781-8977?

NSN 5120-00-781-8977 is a Key,socket Head Screw, manufactured by The American Society of Mechanical Engineers, classified under FSC 5120 (No Item Name Available). Status: cancelled.

What are the part numbers for NSN 5120-00-781-8977?

NSN 5120-00-781-8977 has 18 cross-referenced part numbers: B18.3 (The American Society of Mechanical Engineers), S0764 (Bristol Babcock Inc Instruments-Systems Div Sub of Babcock Intl Inc), A-A-2925 TY2 (General Services Administration Federal Supply Service), S-076-4 (Mahalo Industries Inc Dba Bristol Wrench Co.), A18223-3 (Honeywell International Inc Dba Honeywell) and 13 more.

What NSN replaces 5120-00-781-8977?

There are 12 known substitutes for 5120-00-781-8977: 6150-00-214-2682, 5120-00-224-2482, 5120-00-224-2496 and 9 more. Verify interchangeability with system specifications before substitution.

What are the specifications of B18.3?

Key specifications for B18.3: Overall Length: 1.731 INCHES MINIMUM AND 1.920 INCHES MAXIMUM IN; Wrenching Surface Flute Quantity: 4; Style Designator: L-HANDLE; Wrenching Surface Shape: SPLINE BOTH ENDS EXTERNAL. 10 total characteristics are documented in the Federal Logistics Information System.

Is NSN 5120-00-781-8977 still in active supply?

NSN 5120-00-781-8977 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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