PartsTable TECHNICAL DATA SHEET
JULY 2026Technical Data Sheet

21057Buffer Assembly,recoil

Charles Reed Knight Jr Dba Knight's Armament Company · NSN 1005-01-601-5581 · FSC 1005 · No Item Name Available
Verified by PartsTable
NSN 1005-01-601-5581 — this item is cataloged by the U.S. Government under National Stock Number 1005-01-601-5581. Primary manufacturer part number: 21057.
Features
  • Buffer Assembly,recoil — FSC 1005
  • Overall Diameter: 24.2 MILLIMETERS NOMINAL MM
  • Material: STEEL AND PLASTIC NYLON
  • Surface Treatment: CHROMATE
  • 1 verified cross-reference
  • Primary manufacturer: Charles Reed Knight Jr Dba Knight's Armament Company
Applications
  • Applications requiring Steel and Plastic Nylon construction
General Description

The Buffer Assembly,recoil, cataloged under National Stock Number 1005-01-601-5581, is classified within Federal Supply Class 1005 (No Item Name Available) of the Weapons group. The primary manufacturer of record is Charles Reed Knight Jr Dba Knight's Armament Company. Government technical data includes 3 verified specifications, sourced from the Federal Logistics Information System (FLIS). This item has 1 commercial cross-reference from 1 manufacturer, enabling identification through both NSN and commercial part number lookups. 10 verified substitutes exist in the FLIS interchangeability database. Current acquisition status: Active.

Technical Specifications
ParameterValue
NSN1005-01-601-5581
Primary Part Number21057
Item NameBuffer Assembly,recoil
FSC / FSG1005 / 10 — No Item Name Available
ManufacturerCharles Reed Knight Jr Dba Knight's Armament Company
StatusACTIVE
Overall Diameter24.2 MILLIMETERS NOMINAL MM
MaterialSTEEL AND PLASTIC NYLON
Surface TreatmentCHROMATE
Lifecycle & Compliance
Acquisition StatusACTIVE
HAZMATNo
Verified Substitutes 10
3040-00-463-5261 INTERCHANGEABLE
Shaft,shouldered
5905-00-816-4311210-57 INTERCHANGEABLE
Resistor,variable,nonwire Wound,
Keysight Technologies Inc
5930-01-089-5163 INTERCHANGEABLE
Switch,rotary
5330-01-168-5401 INTERCHANGEABLE
Seal
6140-01-238-4932 INTERCHANGEABLE
Battery Assembly
4810-01-305-316021057 INTERCHANGEABLE
Rack,actuator
Parker Hannifin Corp Dba Pneutronics
5895-01-407-764021057 INTERCHANGEABLE
Modem Assembly,communications
Motorola/codex Corp Sub of Motorola Inc
5310-01-481-5763 INTERCHANGEABLE
Nut,plain,hexagon
4820-01-519-660821057-001 INTERCHANGEABLE
Valve,regulating,fluid Pressure
Sargent Aerospace & Defense, Llc Dba Sargent Controls & Aerospace Div Sargent Controls & Aerospace
5325-01-689-4058 INTERCHANGEABLE
Fastener Tape,hook and Pile
Cross-Reference Index
Part NumberManufacturer
21057 PRIMARY Charles Reed Knight Jr Dba Knight's Armament Company (USA)
Related Parts
3040-00-463-5261INTERCHANGEABLE
SHAFT,SHOULDERED
5905-00-816-4311INTERCHANGEABLE
RESISTOR,VARIABLE,NONWIRE WOUND,
210-57
5930-01-089-5163INTERCHANGEABLE
SWITCH,ROTARY
5330-01-168-5401INTERCHANGEABLE
SEAL
6140-01-238-4932INTERCHANGEABLE
BATTERY ASSEMBLY
4810-01-305-3160INTERCHANGEABLE
RACK,ACTUATOR
21057
5895-01-407-7640INTERCHANGEABLE
MODEM ASSEMBLY,COMMUNICATIONS
21057
5310-01-481-5763INTERCHANGEABLE
NUT,PLAIN,HEXAGON
4820-01-519-6608INTERCHANGEABLE
VALVE,REGULATING,FLUID PRESSURE
21057-001
5325-01-689-4058INTERCHANGEABLE
FASTENER TAPE,HOOK AND PILE

Frequently Asked Questions

What is NSN 1005-01-601-5581?

NSN 1005-01-601-5581 is a Buffer Assembly,recoil, manufactured by Charles Reed Knight Jr Dba Knight's Armament Company, classified under FSC 1005 (No Item Name Available). Status: active.

What are the part numbers for NSN 1005-01-601-5581?

NSN 1005-01-601-5581 has 1 cross-referenced part number: 21057 (Charles Reed Knight Jr Dba Knight's Armament Company).

What NSN replaces 1005-01-601-5581?

There are 10 known substitutes for 1005-01-601-5581: 3040-00-463-5261, 5905-00-816-4311, 5930-01-089-5163 and 7 more. Verify interchangeability with system specifications before substitution.

What are the specifications of 21057?

Key specifications for 21057: Overall Length: 82.6 MILLIMETERS NOMINAL MM; End Item Identification: 7.62 X 51 MM SEMI-AUTOMATIC SNIPER RIFLE M110 MM; Part Name Assigned by Controlling Agency: BUFFER ASSY., M110 CARBINE (HH); Overall Diameter: 24.2 MILLIMETERS NOMINAL MM. 7 total characteristics are documented in the Federal Logistics Information System.

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