S&W Melonite coated barrel vs Noveske chrome lined barrel.

[rsilvers]

I would say 12,500 to 18,700 for chrome lined.

The burden is on you to back up your extraordinary claim.

True to win a debate, but our goal is simply to have barrels which will win military comparison testing.

[montrala]

My source is HK USA, but if you think HKO would nitride blanks before machining - well, that would be pretty odd, as the nitriding would be turned off the outside of the barrel and threads.

HK/O hammer forges complete barrel, with chamber in one process. Nitriding can be applied only to inside of barrel. In fact it can even be applied before chf process. I'm not saying it is - FB Radom tested it this way and it worked.


FB Radom (they were one of first to use rifle barrel bore nitriding on industrial scale) use nitriding only for inside of their barrel... and only for civilian barrels. 17 years ago they approached Polish Army General Staff with results of testing nitrided barrels, that show significant increase of barrel life, accuracy and rust resistance to chrome lined barrels. Army response was: "we can take those new barrels, but you must put chrome lining in it". So Radom is chrome lining military barrels and nitriding hunting/sporting barrels.

Going back to HK barrels: HK MR223 barrel is officialy "not lined". No chrome lining, etc. HK official statement for it is same as from MR556A1 - "this is match rifle, chrome lining reduce accuracy potential". But it works like it would be nitrided. Looks like one as well. My weapons safe is in very humid basement. My Stag barrel showed rust from outside within 2 months (after that I started to put anti rust oil over it every time I put it back into safe). My JP/Cooley brake on my MR223 showed rust within 2-3 month as well (kudos to PWS - FSC91 does not show rust!). But MR223 barres show no rust, even in areas that bare steel came out from under parkerising (on shoulder near muzzle thread). Inside is mirror smooth and cleans very easy. This let me to think it is nitrided. How this apply to MR556A1 barrel? I really do not believe, that after all this years of work to bring MR to US market, HK would settle with barrel worse than is offered on other markets in MR223. "Rusting HK barrels" in MR556 on US market would be like shooting themselves into knee.

[Alpha Sierra]

Seems like good advice maybe but you guys should think twice before treating parts that are critical to safe operation through an irreversible heat treatment without the ability to destructively test to verify. To me, it would be especially ironic for someone to be running a Mil-Spec HPT/MPI bolt in conjunction with a barrel that was once HPT/MPI certified but is now in unknown condition. The big concern is that without extensive testing, you really have no idea what has happened to your safety margins.

Amen.

People should stop playing with the material properties of critical parts in ways they do not understand.

[Alpha Sierra]

Nitriding can be applied only to inside of barrel.

That is simply not true.

[montrala]

That is simply not true.

Depend on process used. Most processes (like ion or plasma process) does not allow it but for example with low temperature gas process (I do not know english name for this process) you can contain gas to barrel bore only. Also when use salt bath for nitriding (like in Melonite process), you can protect selected surfaces from process.

BTW I heard that Melonite process is not longer legal to do in European Union due to environmental concerns.

[rsilvers]

Melonite is a US Trademark for a specific vendor and there are other names for Europe and other markets, Cyanide and non cyanide versions. It is possible that, for example, a cyanide version is no longer legal in Europe but an alternate version is still legal.

[Fabius]

Interesting debate. My take on chrome lining v. nitrocarburizing. Chrome lining was developed for machine gun barrels and full auto rifles. In those applications, barrel life is the top priority and accuracy a secondary consideration because no one puts a scope on a machine gun or uses a scope when firing full auto. The loss of accuracy that can result from chrome lining is less important than the increase in barrel life.

Civilian AR's are for the most part semi-auto, not full auto, but AR manufacturers stuck with chrome lining because its mil-spec for that platform. The loss of accuracy doesn't matter to most, because the AR was not designed to be a sniper rifle.

However, melonite treatment should be a perfectly acceptable alternative for most civilian users. It substantially increases barrel life over untreated barrels, provides excellent corrosion resistance and doesn't sacrifice accuracy.

For manufacturers, like S&W, who are already set up to do melonite treatment, the cost of producing a melonite treated barrel is less than chrome lining. It makes sense for them to offer consumers that option. It also makes sense for some consumers to choose that option, because it is highly unlikely that the average civilian AR owner with a semi-auto rifle will ever shoot out a melonite treated barrel.

So, I commend S&W for giving consumers a high quality, less expensive alternative. I think that it is perfectly reasonable for some consumers to choose that alternative, just as I think that it is perfectly reasonable for other consumers to choose chrome lining. That's the beauty of a free market - consumers get choices.

[montrala]

Chrome lining was developed for machine gun barrels and full auto rifles.

Chrome lining as way to improve small arms barrels longevity was first massively used to make up for poor steel used for war time production in Soviet Union and to make up to complete lack of weapon maintenance by uneducated soviet masses rushed to front, shooting corrosive ammo. Nobody was looking for accuracy - those weapons were used to shoot in general direction of enemy forces.

At same time US used stainless steel on M1 Garand gas cylinders to prevent rusting and specified that M1 Carbine ammo must be non-corrosive (first non-corrosive ammo in military use).

Later on other countries (included US that started to chrome plate gas port area in Garand barrels in late '40s) learned that with chrome lining they can use cheaper steel to make their weapons and that they will require less maintenance from conscripted soldier.

Militaries, while very innovative in some areas, tend to be dead on conservative in others. If chrome lining was good for WW2, it is good now. Why look for better solution for modern warrior - just add lasers and computers and what not, we do not need look inside barrel he use.

[rsilvers]

Fabius,

Your post implies nitriding is not as durable as chrome lining. That is not the case. It is superior for barrel life. There is no good reason to us chrome lining anymore other than certain customers request it.

[jbsmwd]

Fabius,

Your post implies nitriding is not as durable as chrome lining. That is not the case. It is superior for barrel life. There is no good reason to us chrome lining anymore other than certain customers request it.

So where do you go to get a mid-length 4150 barrel that's NOT recce/DMR/heavy profile but is nitride treated.