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Hexavalent Chrome Replacement for Small Caliber Barrels




The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.


OBJECTIVE: Develop and demonstrate a high temperature, corrosion, and wear resistant hexavalent chrome replacement for use on small caliber weapon system barrels.


DESCRIPTION: Small caliber weapon system barrels operate in a high temperature, chemically corrosive, and high mechanical wear environment. This environment leads to rapid deterioration of substrate materials and ultimately, failure of the barrel to meet performance requirements. In extreme cases, the combination of extreme environments can cause catastrophic failure of the weapon system component, resulting in injury to the operator. Future weapon systems are anticipated to further push the extremes with a combination of hotter flame temperature and more chemically corrosive propellants, higher pressures, and harder projectiles. Chrome application processes result in environmentally hazardous byproducts and does not sufficiently perform under the required conditions


There is a need for the development of coatings / plating for barrel bores internal surfaces which can perform / remain adhered under extreme temperatures, and which prevent chemical and mechanical corrosion associated with small arms firing. Proposed coatings / plating shall be compatible chemically, thermally, and mechanically with a variety of materials, both traditional and novel. Proposed coating / plating materials and application processes shall be compatible with small caliber barrel bores as small as 5.56mm in diameter. Further, application processes shall take into account the requirements of the coated / plated components in the small arms system - the application processes shall not adversely affect the substrate material in ways that may affect performance, including dimensional changes or effects on material properties, such as strength or fatigue life.


PHASE I: Phase I is expected to yield the following:

  • Baseline or existing coating / plating properties to be used as starting point for this application, including: Coating thickness, Coating hardness, Coefficient(s) of friction, Corrosion resistance, Color ranges, Operating temperatures and thermal stability, Adhesion to substrate, Chemical compatibility, Application limitations, including internal diameter limitations, Line of sight or Non-Line of sight, substrate compatibility, etc.
  • Baseline or existing coating / plating application parameters, including: Application temperature, Application time, Other relevant application parameters,
  • Baseline or existing coating / plating performance, including: Description of the system and operating environment that the existing coating is applied to,
  • Performance metrics and data in that application
  • Cost of the baseline or existing coating / plating
  • Estimated or predicted properties of the proposed coating / plating, including: Coating thickness, Coating hardness, Coefficient(s) of friction, Corrosion resistance, Color ranges, Operating temperatures and thermal stability, Adhesion to substrate, Chemical compatibility, Application limitations, including internal diameter limitations, substrate compatibility, etc.
  • Predicted application parameters of the proposed coating / plating, including: Application temperature, Application time, Other relevant application parameters
  • Results of all analyses performed to show that the proposed development process will result in coating / plating that will meet the Government's needs, including:
  • Results of modeling and simulation, Results of all analyses, including chemical, thermal, and structural analyses, Ability of the coating / plating to be applied to the internal bore of the barrel, Overall predicted performance in use as a small caliber bore coating or an internal signature suppressor coating
  • Estimated cost of proposed coating / plating


The Offeror is encouraged to provide any other relevant information at the conclusion of Phase I to substantiate that the proposed technology is sufficiently feasible to proceed to Phase II.


PHASE II: The primary deliverables for Phase II should include:

Development of one or more coating(s) / plating(s) formulations and associated application processes that meet the Government's requirements. This deliverable includes all necessary documentation to define the formulation as well as the application process.


A comprehensive report that documents the entirety of the effort. The report shall highlight the development process, results of all analyses performed throughout the development process, results of destructive testing (i.e. coating thickness in sectioned barrels), and contractor's test results in lab (coupon testing) as well as simulated operational environment (live fire testing of coated barrels. The report shall highlight and address any shortcomings in performance, propose potential fixes to these shortcomings, and shall address any anticipated challenges with scaling to full rate production. The report shall also provide estimates of the cost to implement the proposed coating / plating in a production setting.


Quantity of five (5) small caliber barrels with coated / plated bores (weapon system / caliber to be determined - barrels may be provided as GFM).


PHASE III DUAL USE APPLICATIONS: The following post Phase II R&D efforts will be instrumental to transition:

  • Additional Science and Technology development of coatings to improve performance in extreme operating regimes
  • Application of coating / plating to additional quantities of barrels that represent either challenging performance requirements or challenging application requirements.


Virtually all small caliber weapon systems, commercial and military, would benefit from improved barrel systems. There is a large commercial market for small arms, and much money is spent by individuals upgrading barrels. An Offeror would likely need to partner with an OEM barrel manufacturer and have this technology offered as part of the item itself, since it is unlikely that existing barrels would be able to be coated or plated at a reasonable cost to the consumer.


From the DoD/military side, again the technology would apply to virtually all small arms systems, but primarily to advanced next generation systems or legacy belt fed systems that generate large amounts of heat, chemical erosion, and mechanical wear from the projectile. For newly acquired systems, Program Management offices could include this technology as part of the TDP. For legacy systems, the technology could be added to TDPs as Engineering Change Proposals (ECP) and could be included in weapon system overhauls and rebuilds.



  1. Xiaolong Li, Yong Zang, Lei Mu, Yong Lian, Qin Qin, 2020, Erosion analysis of machine gun barrel and lifespan prediction under typical shooting conditions, Wear, Volumes 444-445, 203177, ISSN 0043-1648,;
  2. Sopok, Samuel. (2010). Modeling Gun Bore Heat Transfer & Degradation. 10th AIAA/ASME Joint Thermophysics and Heat Transfer Conference. 10.2514/6.2010-5063.;
  3. Wear and Erosion in Large Caliber Gun Barrels, Richard G. Hasenbein,;
  4. Understanding and Predicting Gun Barrel Erosion, Ian A. Johnston,


KEYWORDS: hexavalent chrome, barrel, advanced coating, high temperature, bore erosion, small caliber, small arms

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