Melonite vs Chrome-Lined Barrels – Differences Explained

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Maybe there are times that you forget or some times that you come home from the field dead tired, but let’s be real—most of the time you’re just too lazy to do your homework as a gun owner. But these days, gun cleaning is not as unforgivable as earlier—thanks to the innovations of different gun coatings.

In this article, we discuss two of the most debated barrel coatings—Melonite and Chrome lining—and help you decide which to opt for considering not only your cleaning habits but also your style of shooting

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TL;DR: Melonite vs Chrome Lined Barrels

Melonite Barrels

Chrome-Lined Barrels

Pros

Pros

Cheaper than chrome lining

Easier to clean

More resistant to corrosion than a chrome

Intended for hard use barrels

Coats both the exterior and interior of the barrel

Chrome will handle the extreme heat better than Nitride

Cons

Cons

The barrel needs to be "shot in" before treatment

More expensive

It will be eroded much quicker than a good chrome lining

Usually, be less accurate

Cell

Chrome plating may go on not perfectly evenly

Cell

Barrel exterior must get an added manganese phosphate treatment

Best For

Best For

Pro shooters and high volume of fire

Tactical applications, rapid fire plinking, and other less accurate applications

What is Melonite Processing? 

Technically, we’re talking about Ferritic Nitro-Carburizing (FNC)—a thermochemical surface hardening process invented in the ‘40s in Germany and England. It was first used in the 1950s by the automotive, aerospace, and firearm industries.

While this treatment is more commonly referred to as FNC or just plain “nitriding,” Melonite is its registered trademark. There are many identical nitriding processes and variations under different trade names, including Tufftride, Tenifer, Ni-Corr, Blacknitride, Arcor, and QPQ.

This process, also known as salt bath nitriding, is used to produce a hard, wear-resistant surface on low steel grades to improve corrosion resistance, durability, and other features.

The firearm industry benefits from the corrosion resistance Melonite processing provides on both the inside and the outside of the barrel.

During this process, a nitride is applied by quenching-polishing-quenching (QPQ) the barrel in a nitrogen-rich salt bath. The nitride penetrates the steel structure by a few thousands of inches, forming alloying elements with chromium, molybdenum, and vanadium in barrel steel.

As for the result, a barrel treated with nitride becomes extremely hard, translated with a Rockwell C hardness system between 62-72.

One of the main differences between Melonite or salt bath nitride (SBN) and Chrome-lining is that the former is a chemical process, while the latter is an electroplating process.

Melonite involves processing at high temperature (975-1,100 degrees F) in a cyanate salt bath, where both nitrogen and carbon bond to the surface and become a "new” hardened surface.

Nitrided gun parts, especially barrels, are apparently all the rage these days, so this coating option is easy to avail in any small arm, from rack-grade semi-autos to high-end, bolt-action rifles.

What is Chrome Lining? 

Chrome lining is the classic and most widespread type of barrel treatment developed during the interwar period.

While chrome plating to small arms and sporting weapon bores was applied as a commercially practical process in 1927 in the USA, Japan's Empire was the earliest nation to adopt the military Type 99 Arisaka 7.7mm rifle with a chrome-plated bore. The U.S. Army only began with chromed small arm bores in the mid-1950s, well after Japanese and Russian adoption of this technology.

In this additive process, the barrel is submerged into a liquid solution. A movable anode is placed in the bore when a current is passed through the bath solution; the chrome bonds to the bore's inside surface, adding chrome material to the bore.

There are many chrome-lining benefits, but its primary role is to protect the rifle barrel (leade and rifling) from excess erosion.

Most military automatic weapons sustain high rates of fire, which markedly increases barrel wear and erosion. As a solution to that, a barrel with a thin coat of heat and pressure-resistant Chrome will significantly extend barrel life in high-powered machine guns and semiautomatic rifles.

Photo credit: thenewrifleman.com

Rifle barrels usually are made from gun steel between 32 and 37 R.C. in hardness on the Rockwell scale, while Chrome measures 72 to 76 R.C.—more than twice as hard as the typical steel barrel.

Hard chrome lining definitely protects the bore, but the barrel must be appropriately machined before the treatment. Unlike a quick "cover-up" coating, hard-chrome plating requires serious machinery. Since it adds to the barrel's physical dimensions, the rifling of the barrel has to be cut slightly oversize to allow chromium deposition.

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Relevant Characteristics Between Melonite and Chrome-Lined Barrels

Melonite Barrel

Characteristics

Chrome Lined Barrel

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Cell

Photo credit: thenewrifleman.com

Slightly more rust resistant

Corrosion Resistance

Very rust resistant

Lower

Heat Resistance

Higher

None

Added Surface Thickness

.0004" to .0015"

Much Lower

Friction Coefficient

Lower, but higher overall friction due to added material

Better

Impact on Accuracy

Slightly worse

Similarities and Differences 

For the average American gun owner, there's not much difference between chrome lining and Melonite. Both barrel treatments will perfectly serve, with only one deciding factor – the price tag for the casual and informal shooting events.

If you care about throat erosion, rust, and corrosion protection, both treatments greatly help minimize these problems compared to the non-lined barrels.

Melonite and Chrome-Lined Barrel Differences 

Whereas Melonite and chrome-lining processes are used for the same purpose, coating and/or finishing barrel treatment, they achieve the goal differently.

Unlike nitriding, which changes the surface properties, chrome lining adds a coating to the interior barrel surface that can be as thick as one-and-a-half thousandths, 0.0015". For that reason, the rifling and barrel must be oversized before the chrome plating process.

Furthermore, as chrome lining is applied only on the rifling and barrel interior, the manufacturer still needs to protect the outside of the barrel using the standard process involving manganese phosphate treatment.

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Hard Chrome insulates the rifling and barrel, significantly extending the barrel life in firearms. It is particularly noticeable under fully automatic fire where an enormous amount of heat is generated. In similar tactical applications or even rapid-fire plinking, the chrome plating will better handle the extreme heat.

One more difference that can be seen by the eyes is that chrome lining finish appears silvery, while Melonite, QPQ, or salt bath ferritic nitrocarburizing treatment results in a gray or black color, more like a deep polished black-bluing.

On the other side, Melonite finish is obtained during the heat treat chemical process done through the gun barrel's immersion in cyanate salt bath for 60-240 minutes at temperatures near the standard for steel in the gun industry. The nitrogen then penetrates the steel forming a hardened surface layer of anywhere between 62-72 HRC.

This method’s main benefit is that barrels can withstand direct exposure to water and corrosive elements better than any other chrome-moly or stainless-steel plain barrel.

Therefore, the surface of nitrided barrels is rendered much more resistant to corrosion when compared to those with chrome-lined barrel treatment.

Melonite and Chrome-Lined Barrel Similarities

First and foremost, both processes are about a century old and well-known in the weapons world.

When it comes to adding protection to the barrel against corrosion and abrasion, both do the job well. Melonite and chrome lining have very close round counts and will save your favorite firearm from a short lifespan and degradation of accuracy.

With increased barrel life and corrosion resistance, both Melonite and chrome-lined barrels benefit any kind of gun owner, to serious riflemen.

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Pricewise, both finishes are significantly more expensive than similar non-lined barrels. However, investing in any of the two presents a great cost-saving measure since they last longer than bare chrome-moly steel or even stainless barrel, usually by a few thousand rounds.

Besides the barrel life, both hard chrome-lining and nitriding methods increase the throat and leade’s life of a treated bore, often double the span of the standard chrome-moly barrels.

Another similarity between the two is the barrel preparation phase before treatment; Chrome-lining can be applied unevenly—the barrel has to be drilled, rifled, and chambered slightly oversize, while a nitrided barrel on the other hand must have a totally clean bore or the process will fail.

Just one note before we proceed to the next subject. Undoubtedly, both treatment methods provide a massive gain in corrosion resistance. But though they are making barrels highly resilient in the face of corrosive environments, neither process is 100% rust-proof.

Advantages of Melonite Barrels 

You have probably noticed the increasing trend towards the Melonite type of barrel treatment in the past couple of years. There are several reasons for that—one on top of those is it is more cost-effective than chrome plating or other barrel solutions.

Unlike barrels that need to be specially fabricated to accommodate chrome-lining treatment, nitrided barrels maintain a dimensional consistency as Nitride does not add any material to the bore.

 During a nitriding process, the nitrogen and carbon molecules are imbued into the metal surface to immensely increase the hardness of the barrel.

Generally, the rifle barrels with Melonite coating are better protected against galling, abrasive wear, and erosion but the primary benefit of this treatment is corrosion resistance. Some manufacturers even claim that their Melonite coating is 85 percent more resistant to corrosion than chrome plating.

One more notable advantage is that Melonite does not shrink nor enlarge the barrel at all, or reduces the rifling’s sharp edges. In addition, the hardened surface layer has a much lower coefficient of friction than chrome-moly steel or chrome plating barrels.

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Moreover, stainless steel barrels are easier nitrided than chrome-lined. The combination of all these features increases velocity, which in turn improves accuracy. While it is nothing noticeable up to 200-300 yards, it is a better option for those who need to reach out and touch something at a longer distance.

Lastly, the nitriding process encompasses the entire barrel, both inside and outside, making it significantly less expensive and less time-consuming than chrome plating.

Here’s a quick summary of the benefits of Melonite barrels:

  • It is a single process in comparison to chrome plating that requires phosphating of the exterior barrel surface

  • Melonite coating dramatically increases corrosion resistance without oil using

  • Melonite protects the inside and outside of the barrel

  • Melonite does not change the dimensions of the bore

  • This treatment offers longer barrel life before degradation of accuracy

  • Melonite process can be easily applied to stainless steel

  • Melonite does not diminish the sharpness of the rifling

Advantages of Chrome Lined Barrels

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Compared to the bare chrome-moly steel barrels, the Chome-lined barrels are more heat, chemical, and erosion-resistant. For that reason, this treatment is highly suitable for military-issued rifles that frequently use corrosive primed ammo.

The chrome-plated mil-spec barrels are an ideal match for full auto and sustained fire because the hard coating protects the barrel from high temperature produced during rapid fire. These features were the main factor in driving the military armorers to notice the advantages of chrome-lined barrels.

Chrome-lined barrels and chambers offer significantly greater corrosion resistance and a very low coefficient of friction. It is particularly important for military rifles and machine guns, as hard chrome-lining also protects the leade and barrel throat, enhancing chambering and extraction.

Another reason to lean towards Chrome-lining is the increased barrel life since they will last longer than non-coated barrels made of chrome-moly steels and stainless steels.

While this process reduces wear and corrosion, the slick hard chrome lining on barrels picks up less jacket material and carbon fouling in the rifling—meaning it does not foul as quickly, making them easier to clean.

A correctly done chrome lining process is superior to Melonite for the reason that it will fill many shallow tool marks like indentations and ridges inside a barrel.

Photo credit: thenewrifleman.com

Here’s the rundown on Chrome barrel benefits:

  • Undoubtedly, Chrome-lined barrels feature longer barrel life, especially when used by military and other full-auto shooters

  • A good chrome-lined barrel will last at least twice the life of a non-lined steel barrel

  • A properly chrome-lined barrel is less susceptible to corrosion, and it is easier to clean

  • Compared to trendy Melonite barrels, a classic chrome lining has a track record of working in the real world

What About Phosphate Coated Barrels?

The oldest of the two previously discussed treatments—the purpose of the phosphating is not to improve the protection of the barrel's interiors, but the outside surfaces. This type of coating is also called Parkerizing after the Parker Rust-Proof Company, which popularized it.

Phosphating or Parkerizing is a chemical conversion coating applied to steel surfaces at temperatures below 250°F in aqueous baths.

When you find a description of a phosphate-coated barrel, it means that only the exterior of a barrel is treated with a phosphate finish because it can't be applied inside standard carbon or stainless-steel barrels.

There are non-lined barrels with Parkerized finish on the market, but you will usually encounter a barrel with a chrome-lined bore and phosphate-coated treatment on the outside.

There are two types of phosphating—zinc phosphate and manganese phosphate. While the matte grey zinc phosphate coating is a great choice for most civilian firearms, the US Army armory system popularizes black manganese phosphating firearms.

Both types are soft and porous compared to Melonite coating, but when combined with proper lubrication, it’s effective in preventing rust and protecting steel surfaces from corrosion for years.

While the Mag Phosphate coating is incredibly resistant to heat elements, its function is somewhat limited compared to the other two coatings since it really does nothing other than protecting the bare metal.

Finally, it is less expensive—making it the most common treatment type applied to most current, military-issued rifles.

Bottom Line

Both processes are about a century old and well known in the firearms world. While you may consider chrome lining as a classic barrel treatment, Melonite or Nitride salt bath is considered the best to date for barrels.

Though manufacturers and dealers emphasize that Melonite's greatest trait is superior corrosion resistance without adding layers to the bore as chrome lining does, we believe that the driving force behind the trend towards this coating is the significantly less expensive and less time-consuming process.

Photo credit: thenewrifleman.com

Nitride was initially developed as a substitute for chrome-lining. As nitriding keeps the barrel's original internal dimensions, it supposedly offers better accuracy than chrome-plated barrels.

Today, the Melonite barrels are go-to options for the general consumer and pro-shooter, while Chrome-lined barrels are typically reserved for sustained, full-auto fire and less accurate applications.

The chrome coating is probably superior on firearms designed for rapid-fire applications such as those found on military and harsh use sporting guns.

People Also Ask

Though the younger shooting community tends to lean towards novelties and insufficiently tested innovations, the consensus is that neither chrome-lining nor Nitride is a better process than the other.

There are even more questions about these barrel treatments for a wider auditorium and less knowledgeable gun enthusiasts as they were shrouded in myths and misconceptions for a long time,

Are Chrome Lined Barrels More Accurate?

The Chrome-lined barrels are obtained by a chrome layer that is electro-mechanically bonded in the barrel.  Since that coating adds a thickness of up to .0015", the barrel will have excellent corrosion and abrasion-resistant properties. Still, a chrome-lined barrel would be less accurate than an equivalent plain chrome-moly barrel due to the inconsistent chrome finish.

However, the loss of accuracy of the chrome-lined barrel is generally unnoticeable, so most shooters will not be able to tell the difference.

How Long Will a Chrome Lined Barrel Last?

Many people will agree that Chrome-lined barrels would last longer than an otherwise identical steel barrel.

While the average non-chrome-lined barrel can last for over 5,000 rounds, your expectations regarding the Chrome-lined barrel's wear life should often go double the length of standard chrome-moly barrels.

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Is Chrome Moly the Same as Chrome Lined?

No, the Chrome-Moly is a type of steel, whereas the chrome-lined term describes the coating process of bore and chamber of a barrel.

Chrome-moly is an abbreviation for chromium molybdenum alloy steel, purposely developed for gun barrels.  On the other hand, chrome-lined means that the inside of a barrel has been plated with hard Chrome.

Is Melonite The Same as Nitride?

Generally, yes, because both names represent a salt bath process where the barrels are treated inside and out. Melonite, Tenifer, or Tufftride are all branding terms for various similar chemical processes performed at high temperatures to create a Nitride layer on the steel.

How to Tell if the Barrel is Melonite or Chrome-Lined?

When you receive a new rifle or buy a used one, the easiest way to tell if the barrel is Melonite or Chrome-lined is the manufacturer's markings stamped on the barrel's top. 

Usually, you can see marks like a "C" or CL (Chrome-lined) with a company name, rifle twist, and other things.

The second way is to look at the bore and chamber of the barrel. 

Chrome-lined has a different look than Melonite, as it has more of a matte or flat sheen and chamber will be white or shiny silver, while the Melonite finish comes with a blackish appearance that feels smooth to the touch. 



He is a military historian enthusiast and hobbyist, war veteran and an avid hunter with more than 30 years of experience. He began reviewing firearms for publications in the mid -1990s and have been fortunate to make many friends in the industry. He has improved continuously his firearms skills and knowledge, which is a never ending journey.