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MS21060 : Mil-Spec Hardware

MS21060 : Mil-Spec Hardware Specification
Nut, Self-Locking, Plate, Two-Lug, Floating, Low Height, CRES, 125 KSI, Ftu, 450°F 800°F

MS21060 CAD DrawingClick on drawing for larger view


1. MATERIAL: Corrosion resistant steel, Type A286 (UNS S66286) in accordance with AMS3525, AMS5732 or AMS5737.

2. FINISH: Only 800°F nuts: silver plate all threaded surfaces of nut element in accordance with AMS 2410. Threads shall show complete coverage. Silver plating on all other surfaces optional. Tarnishing or discoloration of silver not cause for rejection.

3. LUBRICANT: Only 450°F nuts: dry film lubricant in accordance with MIL-N-25027.

4. DIMENSIONING AND TOLERANCING: Dimensioning and tolerancing shall be in accordance with ANSI Y14 5M


6. THREADS: Threads before lubrication in accordance with MIL-S-8879

7. SURFACE TEXTURE: Surface texture unless otherwise specified shall not exceed 125 microinches, in accordance with ANSI/ASME B46 1

8. COUNTERBORE/COUNTERSINK: On size .164 and larger thread relief shall be .062 minimum, on size .138 and smaller, countersink or radiused within “P” diameter

9. PERFORMANCE: See specification, except 450°F dry film lubricated nuts limited to five cycles.

10. FLOAT OF NUT PORTION: Float of nut portion of assembly shall not be less than .030 radially from centered position. Nut element shall be capable of engagement with bolt in the maximum misaligned position.

11. PART NUMBER: The part number shall consist of the basic MS number followed by a dash number from Table 1

Example MS21060L4K

  • MS21060 Basic MS Number
  • L4K Dash Number

MS21060L4K indicates: Nut, self-locking, plate, two lug, floating low height, CRIS; 125 KSI Ftu 450°F; dry film lubrication; .250-28 UNJF-38, countersunk or dimpled holes


  • 1. All dimensions are in inches
  • 2. In the event of a conflict between the text of this standard and the references cited herein the text of this standard shall take precedence.
  • 3. Referenced government (or non-government) documents of the issue listed in that issue of the Department of Defense Index of Specifications and Standards (DODISS) specified in the solicitation form a part of this standard to the extend specified herein
  • 4. Design and usage limitations these nuts are designed to develop the tensile strength of bolts and screws with an ultimate tensile strength of 125 KSI based on the cross section area at the basic root diameter of the threads. These nuts are designed to be used on 3A external threads. These nuts shall be used in accordance with the limitations of MS33588. Only nuts which there are qualified products listed on QPL 25027 shall be used.

Interchangeability Relationship

MS21060 nuts can universally replace NAS686 and NAS1031 nuts of like material, thread size lubricant (dry film or silver plate) rivet spacing and fastening method (plain rivet holes dimpled or countersunk rivet holes or Projection welding), but these NAS686 and NAS1031 nuts cannot universally replace MS21060 nuts.

Need the Spec?

Click here to download MS21060 Specification
(PDF Format).

Great Lakes Fasteners
2204 East Enterprise Parkway
Twinsburg, Ohio 44087

Ohio: 330-425-4488
Nationwide: 800-589-4578
Fax: 330-425-4705

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Copyright Great Lakes Fasteners, Inc. 2008

GLFTechnical Fastener Supply specializes in a wide range of industrial and military specification (MIL Spec) fasteners; including MS fasteners, AN Fasteners, and NAS Fasteners.