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Preview – Finish Strong – A Guide to Coatings, Finishes, and Treatments

For all the advances in polymers and Hollywood nonsense about plastic guns, metal remains the fundamental building block of firearms. And where there is metal, there are many options for how to treat, finish, or coat it. Long past the days of just choosing between bluing or raw stainless steel, we now have a veritable bounty of options. Each has a certain set of characteristics that may make one or another more suitable for your particular needs. Read on to learn more.

Key characteristics to keep in mind include the following:
Hardness, durability, and wear resistance: For hard-use weapons, whether for duty or competition, this is often a key consideration. Thousands of presentations from a Kydex holster, thousands of rounds through a barrel — this will take a toll on metal. For our purposes, standardized hardness testing is measured on the Rockwell C scale (HRC) and Vickers (HV) scale, by putting an indenter under load against the surface.

Corrosion resistance: Carry guns pressed up against your sweaty body or used in maritime or humid environments are often a recipe for rust and corrosion. It’s not a license to abuse your gear, but finishes intended for this purpose can help a lot — of course, remember that nothing is truly corrosion proof. While it cannot exactly represent real-world performance, a standardized salt spray test (ASTM B-117) is typically used to assess the corrosion resistance of materials and finishes. In such a test, the parts are placed in a testing chamber and exposed to a dense fog of 5-percent salt solution until they begin to show the effects of corrosion.

Titanium Nitride by Coasting Services GroupGlock Store 19 - Titanium Nitride

Lubricity: Many finishes have very low coefficients of friction — a measure of how easily one surface slides against another. For example, the coefficient of friction for steel on steel is over 0.7 dry and around 0.2 with lubrication, which is more than halved by many of the coatings. Again, we always advocate properly lubricating your weapons, but these finishes enhance performance and provide you with more leeway in your maintenance schedule.

Type of material/substrate: Some finishes or treatments can only be applied to steel, not to aluminum or polymers. Note also that many companies and end users mix and match finishes on different components.

Method of application: Some require high heat, electrical processes, or specific characteristics, which may completely preclude use on, or else not be desirable for certain components (e.g. an optic, non-ferrous metals, non-conductive materials, etc).

Tolerances: All except one of these processes add material to the substrate, so this must be considered for specific applications (e.g. slide rails, sears, etc). In some cases, high-tolerance areas might be masked off, require some fitting afterwards, or even be considered in advance during gunsmithing or manufacturing, given an intended coating (e.g. with custom 1911 builds or chrome-lined barrels).

Aesthetics: Desired color, surface treatment, and ability to mask flaws in the base metal all come into play here.

Cost: Specialized equipment and solutions, as well as how time and labor intensive the process is, factor into the cost. Note also that many processes benefit from economies of scale, so one-offs can be more expensive or your job might need to be batched with others to bring down the cost, potentially increasing wait times.

It may go without saying, but a reliable, experienced shop with talented craftsmen is important to achieving satisfactory results. As with so many things, prep work is absolutely critical, equipment can set limitations on what a shop is capable of, and attention to detail (whether in properly maintaining the chemistry of solutions or achieving proper tolerances) will ensure a good end product. Do your research and set realistic expectations.

Kimber - NP3 FinishHydrographics - MultiCam

H&M Metal Processing - Ferritic NitrocarburizingOD Green Cerakote AR-15For the rest of this article, subscribe here: RECOIL Issue 13

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