February 18th, 2009

Melonite Surface Treatment for Barrels, Bolts, and Actions

Melonite surface hardeningAce trigger-puller Joel Kendrick, a former IBS 600-yard Shooter of the Year, has been working on a MELONITE┬« nitrocarburizing process for surface-hardening barrels and other gun parts. The main advantage of Melonite barrel treatment is that it reduces friction in the bore and lessens bore surface wear, potentially extending barrel life. Melonite-treatment of a bore creates a new compound layer in the top 10-20 microns of the surface, creating a very hard, slick surface. Joel has found that this surface is so slick that carbon does not easily adhere, so the barrel is easier to keep clean. Real-world tests have shown that Melonite barrel treatment definitely reduces internal barrel friction. Joel notes that, after processing, barrels deliver 50 to 100 fps LESS velocity with the same load, a reliable indicator of reduced friction. (Likewise, you’ll get less velocity when switching from naked to moly-coated bullets.) Butch Lambert has tried some Melonite-treated barrels, and he reports: “I have had Joel Kendrick do three barrels for me in Melonite. I polished them first and the finish is like a deep polished black-bluing. One Krieger has 5000 rounds on it and it is shooting just as well as when new. It has been an incredible barrel. It has no throat erosion. It has developed a bunch of pinprick looking spots in the throat, but doesn’t seem to hurt anything. The finish is so hard you can’t thread it. I have not put one of the LV barrels on yet and the heavy is a great shooter and doesn’t have many rounds on it. My experience has been great, but a more extensive test is needed.”

Salt-bath nitrocarburizing by Melonite process has been applied in a wide range of industries throughout the world for many decades. It is used to improve the wear resistance, the fatigue strength, and corrosion resistance of components made from steel, cast iron, and sintered iron materials. The Melonite process is used as an alternative to other surface engineering processes such as case hardening.

Kendrick Melonite barrel

Joel tells us: “I have been experimenting with this Melonite process for the last five years. I have been testing nitrocarburized barrels on my F-class and Long Range equipment since 2005 with good results. What will it cost? Joel expects Melonite treatment will cost under $100.00 per barrel, but the final pricing structure hasn’t been set yet. There will be volume discounts for gunsmiths and manufacturers.

There are many potential applications of Melonite processing for shooters, Joel believes. In addition to barrels, bolts, actions, internal components, and even reloading equipment can be surface-hardened with the Melonite process. After processing, the surface compound layers formed consist of iron, nitrogen, carbon and oxygen. Due to its microstructure, the compound layer does not possess metallic properties. Depending on material used, the compound layer will have a Vickers hardness of about 800 to 1500 HV, and a layer depth of 10 to 20 micorons. That’s so hard that conventional reamers won’t work well on a Melonited surface, so the barrel must be chambered BEFORE Melonite processing.

Kendrick Melonite barrel

Lower Friction, Less Throat Erosion, Longer Barrel Life
Joel believes there are many benefits to Melonite barrel processing. The barrels he has treated and tested have shown reduced fouling, less throat erosion, and extended useful barrel life. Melonite-treated Chrome-moly barrels will have improved corrosion resistance as well. But are there negatives? According to Joel, “with stainless barrels, Melonite processing may reduce corrosion resistance slightly. Also, the treatment process makes the surface so hard that re-chambering is not practical — so this is something you do to already-chambered barrels.”

What about accuracy? Joel says: “Melonite barrel treatment should have no effect, positive or negative, on accuracy… except to the extent that your barrel may retain its best accuracy longer since it won’t wear out as fast.”

To learn more about the Melonite nitrocarburizing process and its application to shooting products, contact Joel Kendrick, joelkndrck [at] aol.com, or call (704) 616-6442.

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