PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

B1821BH031F125NScrew,cap,hexagon Head

American National Standards Institute Incorporated Dba American National Standards Institute · NSN 5305-00-051-4078 · FSC 5305 · No Item Name Available
Verified by PartsTable
NSN 5305-00-051-4078 — this item is cataloged by the U.S. Government under National Stock Number 5305-00-051-4078. Primary manufacturer part number: B1821BH031F125N.
Features
  • Screw,cap,hexagon Head — FSC 5305
  • Thread Series Designator: UNF
  • Thread Direction: RIGHT-HAND
  • Nominal Thread Diameter: 0.312 INCHES IN
  • Material: STEEL OVERALL
  • Hardness Rating: 32.0 ROCKWELL C MINIMUM AND 38.0 ROCKWELL C MAXIMUM OVERALL
  • Material Document and Classification: ASTM A354, GRADE BD ASSN STD SINGLE MATERIAL RESPONSE OVERALL
  • Thread Quantity Per Inch: 24
Applications
  • Structural fastening and assembly
  • Equipment mounting
  • Panel and housing attachment
  • Applications requiring Steel Overall construction
General Description

The Screw,cap,hexagon Head, cataloged under National Stock Number 5305-00-051-4078, is classified within Federal Supply Class 5305 (No Item Name Available) of the Hardware and Abrasives group. The primary manufacturer of record is American National Standards Institute Incorporated Dba American National Standards Institute. Government technical data includes 15 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 10 commercial cross-references from 8 manufacturers, enabling identification through both NSN and commercial part number lookups. 3 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Cancelled.

Technical Specifications
ParameterValue
NSN5305-00-051-4078
Primary Part NumberB1821BH031F125N
Item NameScrew,cap,hexagon Head
FSC / FSG5305 / 53 — No Item Name Available
ManufacturerAmerican National Standards Institute Incorporated Dba American National Standards Institute
StatusCANCELLED
Thread Series DesignatorUNF
Thread DirectionRIGHT-HAND
Nominal Thread Diameter0.312 INCHES IN
MaterialSTEEL OVERALL
Hardness Rating32.0 ROCKWELL C MINIMUM AND 38.0 ROCKWELL C MAXIMUM OVERALL
Material Document and ClassificationASTM A354, GRADE BD ASSN STD SINGLE MATERIAL RESPONSE OVERALL
Thread Quantity Per Inch24
Width Between Flats0.489 INCHES MINIMUM AND 0.500 INCHES MAXIMUM IN
Head StyleHEXAGON
Surface Treatment Document and ClassificationASTM B633, TYPE FE/ZN5 OR FE/ZN8 ASSN STD ALL TREATMENT RESPONSES OVERALL
Thread Class2A A
Surface TreatmentZINC AND CHROMATE OVERALL
Head Height0.195 INCHES MINIMUM AND 0.211 INCHES MAXIMUM IN
Fastener Length1.250 INCHES NOMINAL IN
Thread Length0.875 INCHES MINIMUM IN
Lifecycle & Compliance
Acquisition StatusCANCELLED
HAZMATNo
Verified Substitutes 3
2805-00-356-1579 INTERCHANGEABLE
Valve,poppet,engine
5306-00-543-5727 INTERCHANGEABLE
Bolt,machine
5365-01-190-2130186505 INTERCHANGEABLE
Shim
Woodward, Inc. Div Fuel Systems and Controls
Cross-Reference Index
Part NumberManufacturer
AESQ1F312A25AW9A91 The American Society of Mechanical Engineers (USA)
MS35304-36 Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M
186505 Rolls-Royce Solutions America Inc (USA)
223587 CAGE 00000
B1821BH031F125N PRIMARY American National Standards Institute Incorporated Dba American National Standards Institute (USA)
63-CL-3335-1 PRIMARY Rockford Powertrain Inc Div Powertrain Rockford, Inc. (USA)
C10-26066 PRIMARY Brunswick Corp Dba Mercury Marine Div Mercury Marine (USA)
157D4350-105 PRIMARY General Dynamics-Ots, Inc. Div Ordnance and Tactical Systems (USA)
5306000514078 E.c.a Etablissement Central Des Approvisionnements Des Forces Armees Royales
MS90727-36 Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M
Related Parts
2805-00-356-1579INTERCHANGEABLE
VALVE,POPPET,ENGINE
5306-00-543-5727INTERCHANGEABLE
BOLT,MACHINE
5365-01-190-2130INTERCHANGEABLE
SHIM
186505

Frequently Asked Questions

What is NSN 5305-00-051-4078?

NSN 5305-00-051-4078 is a Screw,cap,hexagon Head, manufactured by American National Standards Institute Incorporated Dba American National Standards Institute, classified under FSC 5305 (No Item Name Available). Status: cancelled.

What are the part numbers for NSN 5305-00-051-4078?

NSN 5305-00-051-4078 has 10 cross-referenced part numbers: AESQ1F312A25AW9A91 (The American Society of Mechanical Engineers), MS35304-36 (Military Standards Promulgated by Military Departments Under Authority of Defense Standardization Manual 4120 3-M), 186505 (Rolls-Royce Solutions America Inc), 223587, B1821BH031F125N (American National Standards Institute Incorporated Dba American National Standards Institute) and 5 more.

What NSN replaces 5305-00-051-4078?

There are 3 known substitutes for 5305-00-051-4078: 2805-00-356-1579, 5306-00-543-5727, 5365-01-190-2130. Verify interchangeability with system specifications before substitution.

What are the specifications of B1821BH031F125N?

Key specifications for B1821BH031F125N: Thread Series Designator: UNF; Thread Direction: RIGHT-HAND; Nominal Thread Diameter: 0.312 INCHES IN; Material: STEEL OVERALL. 15 total characteristics are documented in the Federal Logistics Information System.

Is NSN 5305-00-051-4078 still in active supply?

NSN 5305-00-051-4078 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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