Top 27 Mil-Spec Fastener Questions & Expert Answers on AN, MS, NAS & MIL-STD Hardware Frequently Asked Questions About Military Standard (MIL-STD) Hardware (Part 2 of 4)
Posted: February 24, 2026 Filed under: DFARS, Domestic Fasteners, Mil-Spec Fasteners | Tags: Certificate of conformance, COC, DFARS Compliant, Domestic Fasteners, Mil-spec, Mil-spec fasteners, Mil-Spec Fasteners Cross-Reference, Mil-Spec Fasteners Distributor, Mil-Spec Fasteners Supplier Leave a comment
Welcome back to our 4-part series on Mil-Spec Fastener Questions and Expert Answers. In part one, we covered what makes a fastener truly Mil-Spec. In Part 2, we focus on Mil-spec fastener compliance, certifications, and documentation.
In this installment, we break down DFARS and specialty metals, qualifying countries, certification and COC requirements. We also cover when additional documentation must be requested, how to interpret Mil-Spec part numbers, and where to obtain official prints and supporting documentation, the practical checkpoints in the life of a Mil-Spec fastener.
Part 2 – DFARS Specialty Metals, COCs/MTRs & Compliance Paperwork
8. What does DFARS compliance mean?
DFARS (Defense Federal Acquisition Regulation Supplement) compliance means that the specialty metals used in the fasteners are sourced and manufactured from approved countries. DFARS is often required for Defense Department related contracts.
9. What materials are DFARS-eligible?
DFARS only pertains to fasteners made from “specialty metals” including stainless steel, high alloy steel, like Grade-BD, or Grade 5 Chromium steel with high chromium content. “Specialty metals” means:
- Steel:
- With a maximum alloy content exceeding one or more of the following limits:
- 1.65% Manganese
- 0.60% Silicon
- 0.60% Copper
- With a maximum alloy content exceeding one or more of the following limits:
- Metal alloys consisting of:
- Containing more than 0.25% of any of the following elements:
- Aluminum
- Chromium
- Cobalt
- Molybdenum
- Nickel
- Niobium (Columbium)
- Titanium
- Tungsten
- Vanadium
- Containing more than 0.25% of any of the following elements:
- Titanium and titanium alloys
- Nickel or iron-nickel alloys that contain a total of alloying metals other than nickel and iron in excess of 10%.
- Cobalt alloys that contain a total of alloying metals other than cobalt and iron in excess of 10%.
- Zirconium and zirconium alloys
“Steel” means an iron alloy that includes between .02 and 2 percent carbon and may include other elements.
Restriction: Except as provided in paragraph (c) of this clause, any specialty metals incorporated in items delivered under this contract shall be melted or produced in the United States, its outlying areas, or a qualifying country.
10. More about DFARS
Almost a decade ago, the term “DFARS Compliant Material” came to the forefront for companies supplying parts and services to the government. The original Federal Acquisition Regulation (FAR) clause 252.225-7014 specified “A Preference for Domestic Specialty Metals.” What that means in our world is that for fasteners to be DFARS compliant, the metal used to fabricate them must be melted or manufactured in the United States or a qualifying country.
Qualifying countries: Australia, Austria, Belgium, Canada, Czech Republic, Denmark, Egypt, Finland, France, Germany, Greece, Israel, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, Turkey, United Kingdom of Great Britain and Northern Ireland. Visit the DPC website, section 252.225, or the ACQ website to keep up to date with DFARs requirements, which were updated January 2023. To learn more about DFARS as it pertains to Mil-Spec fasteners, refer to this link.
11. How do I know if a fastener is Mil-Spec certified?
Mil-Spec fasteners are commonly supplied with a manufacturer’s Certificate of Conformance (COC) referencing the part number which calls out the standard the fastener is made to.
12. What paperwork comes with Mil-Spec fasteners?
Although Mil-Spec fasteners are commonly provided with the Manufacturer’s Certificate of Conformance (COC), other paperwork such as Material Test Report (MTRs), Plating or Heat Treatment Certifications, DFARS certification, Lot traceability or Dimensional Test reports may also be available and sometimes involve a fee.
Here is a more extensive list of paperwork that might accompany Mil-spec fasteners:
- Manufacturer’s Certificate of Conformance (COC)
- Verifies that the parts meet the specified Mil-Spec standard
- Should include part number, lot number, specification, and manufacturer info
- Material Test Reports (MTRs) (if required)
- Confirms the chemical and mechanical properties of the raw material
- Typically needed for DFARS compliance or aerospace contracts
- DFARS Compliance Statement (if applicable)
- Required if your project is subject to DFARS specialty metals clause
- Should confirm country of melt and manufacture is DFARS-approved
- Plating or Finish Certifications (if applicable)
- Certifies any surface treatments (e.g., cadmium, zinc, passivation) meet required specs
- Heat Treat Certification (for heat-treated parts)
- Confirms the heat treatment process meets the Mil-Spec requirements
- Dimensional or Inspection Reports (on request or for critical parts)
- Documents that parts were inspected and meet dimensional tolerances
- Lot Traceability
- Ensures all fasteners in your order can be traced back to the original manufacturing lot
13. How do I read a Mil-Spec part number?
Each character in the part number provides information about the size, material, thread, and finish. For example, MS24693C4, sometimes expressed MS24693-C4 or MS24693C-4 is a 4-40 x 3/8 Phillips Flat 100 Degree Machine Screw in 300 Series Stainless Steel. Contact us if you need help decoding a part number!
14. Where can I get a print of a Mil-Spec part number?
Documentation for MIL-STD parts are maintained by the Defense Logistics Agency (DLA). The Aerospace Industries Association (AIA) has a database of prints available for purchase.
The fastest way to avoid delays is to align documentation requirements up front, especially when DFARS applies or when your flowdown calls for more than a standard COC.
Lessons learned: Mil-spec fastener compliance, certifications, and documentation.
Material test reports, plating/finish certs, heat-treat certs, dimensional/inspection reports, and lot traceability can be available, but they often need to be explicitly requested, and sometimes also carry added cost, so it’s smart to define that scope before release and ensure all needed documents are included during your receiving process.
In our next installment, Part 3, we’ll shift from compliance to sourcing strategy: where to find Mil-Spec catalogs/specs, what types of MIL-STD hardware are commonly used, which materials show up most, and how to think about functional equivalents and cross-referencing without compromising requirements.
In the meantime, if you have any questions, feel free to Connect withour team or send us a request for quote and our team of sourcing experts will help you find what you need. “Finding the right screw for you” is our tag line after all!
Related:
- Top 27 Mil-Spec Fastener Questions & Expert Answers Part 1 (Blog)
- Buyer’s Guide to Mil-Spec Fasteners
- Mil-Spec DFARS!? What the heck is that?
- Mil-Spec Fasteners Guide: Frequently Asked Questions
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