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TacticalDon
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Posted: 12/14/2011 7:02:39 PM
What is melonite barrel finish? Is it inside the barrel like a chrome lined barrel?
FrankSL
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Posted: 12/14/2011 7:11:13 PM
Originally Posted By TacticalDon:
What is melonite barrel finish? Is it inside the barrel like a chrome lined barrel?


Yes.

TacticalDon
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Posted: 12/14/2011 7:12:09 PM
Originally Posted By FrankSL:
Originally Posted By TacticalDon:
What is melonite barrel finish? Is it inside the barrel like a chrome lined barrel?


Yes.



How is it compared to a chrome lined barrel? Is it any good?
zulthor
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Posted: 12/14/2011 7:14:57 PM
[Last Edit: 12/14/2011 7:15:23 PM by zulthor]
Yes, it's inside the barrel and outside. Without getting technical it's a treatment for metal that makes the surface harder than chrome and pretty slick

It's better than chrome
6winchester2
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Posted: 12/14/2011 7:46:26 PM
As noted in the reply above, from what I have read melonite is more durable than chrome.
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Posted: 12/14/2011 8:21:11 PM
http://www.thetruthaboutguns.com/2011/06/benjamin-t-shotzberger/%EF%BB%BF-gun-review-smith-and-wesson-mp15-sport/

The M&P15 Sport’s barrel isn’t an M4 cut; if you’re looking to mount your M203, look elsewhere. The Smith sports a full-profile barrel of American 4140 Steel. The bolt carrier and gas key are chromed, and the barrel sports their Melonite coating. Smith claims that the bare bones approach has no effect on durability. They’ve fed two M&P15 Sport test rifles a combined ~170,000 rounds of various brands of ammunition without any [visible] damage to the Melonite finishing process.


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gunner76
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Posted: 12/14/2011 8:29:27 PM
CMMG's WASP coating is pretty much the same thing. I had a couple of their AR's with this and had good luck with them, accuracy was good and the barrels cleaned up easily. I've also heard it's better than chrome.
AR18
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Posted: 12/14/2011 9:48:22 PM
Melonite is great against corrosive munitions.
6winchester2
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Posted: 12/14/2011 9:51:19 PM
Originally Posted By AR18:
Melonite is great against corrosive munitions.


Stellite is good too.

Many heavy machine guns have stellite lined barrels.
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50cal
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Posted: 12/14/2011 10:14:38 PM
Originally Posted By 6winchester2:
Originally Posted By AR18:
Melonite is great against corrosive munitions.


Stellite is good too.

Many heavy machine guns have stellite lined barrels.



I thought those were just the chambers?
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Gamma762
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Posted: 12/15/2011 12:50:50 AM
[Last Edit: 12/15/2011 11:02:32 PM by Gamma762]
Originally Posted By 50cal:
Originally Posted By 6winchester2:
Originally Posted By AR18:
Melonite is great against corrosive munitions.

Stellite is good too.
Many heavy machine guns have stellite lined barrels.

I thought those were just the chambers?

The stellite barrels usually had a liner that went from the chamber out to something like 8 inches, then steel in front of that to the muzzle. Only put it in the highest heat area of the barrel, but a difficult process to precisely machine both parts of metals and precisely fit them together to match up the rifling lands and such. Really an amazing piece of technology.

Back to the OP's question, Melonite is a trade name for a salt-bath ferritic nitrocarburizing treatment process. "QPQ Nitriding" is a generic term for that kind of a process. Wikipedia has a reasonable page on ferritic nitrocarburizing, and if you want to see what the process looks like do a youtube search for "modern marvels salt" - the show "Modern Marvels" included some info on the salt-bath nitriding process in their program on "salt". IIRC you skip forward about 30 minutes into the video to get to the nitriding part.

ETA:
Wikipedia: http://en.wikipedia.org/wiki/Ferritic_nitrocarburizing
Youtube: http://www.youtube.com/watch?v=pCLzUcJrdOk Skip to the 33:00 minute mark.

Unlike chrome lining, nitriding processes change the steel at and under the surface instead of adding a layer of material. This allows more precise control of dimensions. In addition, unlike a separate layer of a dissimilar metal, the nitrided layer is integral with the rest of the steel barrel and doesn't experience crazing from thermal cycling. It's also much thicker than any additional layer like chrome, so a bore for example would be utterly worn and useless before you'd wear through the nitrided layer. Nitride, when done to carbon steels, results in very corrosion resistant as well as very hard, durable surfaces. Stainless steels are a poorer choice for salt bath nitriding processes because the different elements in the stainless alloys result in much reduced corrosion resistance, as well as lower heat resistance that's inherent in the underlying steel. Nitrided stainless means more expense for a poorer performing product.
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Troll_account
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Posted: 12/15/2011 10:06:08 AM
Originally Posted By Gamma762:
Originally Posted By 50cal:
Originally Posted By 6winchester2:
Originally Posted By AR18:
Melonite is great against corrosive munitions.

Stellite is good too.
Many heavy machine guns have stellite lined barrels.

I thought those were just the chambers?

The stellite barrels usually had a liner that went from the chamber out to something like 8 inches, then steel in front of that to the muzzle. Only put it in the highest heat area of the barrel, but a difficult process to precisely machine both parts of metals and precisely fit them together to match up the rifling lands and such. Really an amazing piece of technology.

Back to the OP's question, Melonite is a trade name for a salt-bath ferritic nitrocarburizing treatment process. "QPQ Nitriding" is a generic term for that kind of a process. Wikipedia has a reasonable page on ferritic nitrocarburizing, and if you want to see what the process looks like do a youtube search for "modern marvels salt" - the show "Modern Marvels" included some info on the salt-bath nitriding process in their program on "salt". IIRC you skip forward about 30 minutes into the video to get to the nitriding part.

Unlike chrome lining, nitriding processes change the steel at and under the surface instead of adding a layer of material. This allows more precise control of dimensions. In addition, unlike a separate layer of a dissimilar metal, the nitrided layer is integral with the rest of the steel barrel and doesn't experience crazing from thermal cycling. It's also much thicker than any additional layer like chrome, so a bore for example would be utterly worn and useless before you'd wear through the nitrided layer. Nitride, when done to carbon steels, results in very corrosion resistant as well as very hard, durable surfaces. Stainless steels are a poorer choice for salt bath nitriding processes because the different elements in the stainless alloys result in much reduced corrosion resistance, as well as lower heat resistance that's inherent in the underlying steel. Nitrided stainless means more expense for a poorer performing product.


Which surface is harder? Nitride or Chrome?

The_Texan_Ninja
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Posted: 12/15/2011 10:10:25 AM
Originally Posted By Troll_account:
Originally Posted By Gamma762:
Originally Posted By 50cal:
Originally Posted By 6winchester2:
Originally Posted By AR18:
Melonite is great against corrosive munitions.

Stellite is good too.
Many heavy machine guns have stellite lined barrels.

I thought those were just the chambers?

The stellite barrels usually had a liner that went from the chamber out to something like 8 inches, then steel in front of that to the muzzle. Only put it in the highest heat area of the barrel, but a difficult process to precisely machine both parts of metals and precisely fit them together to match up the rifling lands and such. Really an amazing piece of technology.

Back to the OP's question, Melonite is a trade name for a salt-bath ferritic nitrocarburizing treatment process. "QPQ Nitriding" is a generic term for that kind of a process. Wikipedia has a reasonable page on ferritic nitrocarburizing, and if you want to see what the process looks like do a youtube search for "modern marvels salt" - the show "Modern Marvels" included some info on the salt-bath nitriding process in their program on "salt". IIRC you skip forward about 30 minutes into the video to get to the nitriding part.

Unlike chrome lining, nitriding processes change the steel at and under the surface instead of adding a layer of material. This allows more precise control of dimensions. In addition, unlike a separate layer of a dissimilar metal, the nitrided layer is integral with the rest of the steel barrel and doesn't experience crazing from thermal cycling. It's also much thicker than any additional layer like chrome, so a bore for example would be utterly worn and useless before you'd wear through the nitrided layer. Nitride, when done to carbon steels, results in very corrosion resistant as well as very hard, durable surfaces. Stainless steels are a poorer choice for salt bath nitriding processes because the different elements in the stainless alloys result in much reduced corrosion resistance, as well as lower heat resistance that's inherent in the underlying steel. Nitrided stainless means more expense for a poorer performing product.


Which surface is harder? Nitride or Chrome?



Nitride is considerably harder than chrome lining
Troll_account
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Posted: 12/15/2011 10:22:33 AM
I dont mean to insult you, but are you sure? We are still using chrome lining in the military, is it institutional inertia? From what I understand meloniting is cheaper to do and makes consistent barrels?
Why are we still using chrome lining?
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Posted: 12/15/2011 10:50:05 AM
Inertia. It takes the military many years to make even the most basic of changes.
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Posted: 12/15/2011 10:50:05 AM
How would this (Melonite) work for bolts and BCGs? Or would it not be worth the cost?
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Posted: 12/15/2011 11:51:15 AM
Originally Posted By bmyk:
How would this (Melonite) work for bolts and BCGs? Or would it not be worth the cost?


J.P. Enterprises offers melonite carriers.
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LJP
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Posted: 12/15/2011 12:08:11 PM
As an aside, Glock uses essentially the same process on their slides and barrels; as I recall, they have a different name for it (tenifer I think it is) instead of melonite. There are variations of the "melonite" process –– different tempatures and maybe other parts of the process. I think the Wikipedia article someone here referenced talks about the differences. But, as others have said, the idea is to create a long-wearing and corrosion resistant finish that penetrates into, versus onto, the steel.
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Posted: 12/15/2011 12:29:51 PM
Ok started digging into it. Meloniting/Nitrocarburizing gets ya hardness ranges from 800 to 1500 HV depending on the steel grade. Chrome hovers around 900 Hv and 1200 being the absolute maximum and VERY hard to achive.
Thanks guys! this is VERY interesting.
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Posted: 12/15/2011 12:38:01 PM
Maybe I should give these barrels a try? LaRue melonites their barrels right?
Combat_Jack
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Posted: 12/15/2011 1:57:48 PM
No, LaRue uses LW-50 stainless.
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Posted: 12/15/2011 1:59:40 PM
Originally Posted By Combat_Jack:
No, LaRue uses LW-50 stainless.


That is the material of the barrel not the finishing process.

Gamma762
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Posted: 12/15/2011 2:19:58 PM
[Last Edit: 12/15/2011 2:56:02 PM by Gamma762]
Originally Posted By Troll_account:
Originally Posted By Combat_Jack:
No, LaRue uses LW-50 stainless.

That is the material of the barrel not the finishing process.

Still not melonited AFAIK, I believe that they "Ion Bond" the exterior of their barrels - Ion Bond is a trade name for a Physical Vapor Deposition coating process. And as I mentioned, nitride in general is not the best option for stainless.... or rather, if you're going to nitride, stainless is not the best option. From my understanding there are some lower temperature (non-ferritic) gas or plasma nitriding processes in development for stainless, but in general, why bother? Nitrided CM/CMV steels offer higher performance at lower cost.

Originally Posted By Troll_account:
I dont mean to insult you, but are you sure? We are still using chrome lining in the military, is it institutional inertia? From what I understand meloniting is cheaper to do and makes consistent barrels?
Why are we still using chrome lining?

Because the specifications say chrome.

If you want to use melonite, get new weapons/products adopted that use it, along with a complete specifications technical package so that they know how to deal with it.

Despite the apparent advantages there may be some cases where chrome is still a better choice. Something that used to get trotted out often was a couple decades old military test on 25mm cannon barrels where they compared a nitrided barrel (not sure what process) to the existing chrome lined, and got longer life out of the chrome. Large caliber barrels for cannons and artillery do have some different characteristics than small arms barrels, or it may have just been differences in the process that was used versus current processes.

One thing that is often overlooked in the "newness" of nitride to the firearms market is that it's really not new, even to the firearms market. HK for example has been using nitriding processes since the 60's, most all of their products have used some kind of nitriding (mostly gas nitriding) on various parts since that time. Nitride has been widely used for parts for the oil industry and especially the nuclear industry for almost as long, as well as automotive and industrial parts and other users. When I mentioned nitriding to my father he told me about his experiences with nitrided aircraft engine parts from the late 50's/early 60's. It just hasn't been traditional for firearms in the US and not "mil spec".
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Posted: 12/15/2011 2:39:04 PM
Do you know how the friction coefficents compare?
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Posted: 12/15/2011 10:23:22 PM
Originally Posted By LJP:
As an aside, Glock uses essentially the same process on their slides and barrels; as I recall, they have a different name for it (tenifer I think it is) instead of melonite. There are variations of the "melonite" process –– different tempatures and maybe other parts of the process. I think the Wikipedia article someone here referenced talks about the differences. But, as others have said, the idea is to create a long-wearing and corrosion resistant finish that penetrates into, versus onto, the steel.


Tenifer is correct.

Adams Arms uses Melonite on the bores and exterior of their barrels and BCGs of their 5.45x39 piston uppers. I have one and have only used surplus corrosive ammo in my rifle. It holds up extremely well. After almost 2000 rounds it still looks like the day I got it. I know thats not a lot of rounds but I've heard stories of untreated components exhibiting signs of corrosion if left unattended after only one shooting session. It appears to clean up and hold up extremely well.
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Posted: 12/16/2011 7:01:39 AM


I didn't know they coated barrel's too?
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