Nitride finished AR-15 barrels - Thoughts?

They are only popular because hard chrome is difficult to apply in the US for environmental reasons.

The technology when applied to firearm barrels is pretty new so it isn't well established how exactly it compares.

One of the few things that is generally agreed upon is that it allows for greater accuracy potential than chrome since it's a surface hardening treatment rather than a potentially uneven coating.

I agree with Koznak and further have found the exterior to be more protective than phosphate, most dings wipe away with an oily rag. Most of my pile of AR's have nitride treated BCG and barrels, the nitride in my opinion cleans up better than ni boron and does not stain like the ni baron can.
I have both QPQ nitride barrels and chrome lined traditional barrels as well as CHF--- chrome lined and can tell no difference in accuracy.

I don't know what the barrel life will be (other than that it will be better than bare chrome molly) but in terms of rust resistance and lubricity and uniform thickness the variations on salt bath ferritic nitrocarburizing seem like good choices.

They are only popular because hard chrome is difficult to apply in the US for environmental reasons.

They are popular because nitried is a surface hardening treatment, which phosphate or blueing does not do. More importantly, the rifling is the same as broached, with no additive plating. That means it's consistently more accurate if properly performed, and also can add a few fps to the velocity. Chrome has to be rifled oversized as the plating builds up the final dimension, and its also problematic about being concentric as the process is difficult to control. Barrels are routinely discarded - or salvaged in shorter lengths - because of bore obstructions due to uneven waviness in the bore. Tight spots can cause pressure spikes which can be dangerous - one early vendor of an alternate AR cartridge went out of business because of poor quality control by the plater.

Nitride avoids all that and makes for a better more concentric bore in large scale production, and is equally corrosion resistant. For the most part the Euro battle rifle companies switched to nitride decades ago when they went to cold hammer forged barrels. It was Colt who dragged their feet over it and the US Army saw no need to force the issue as they could provide milspec 2MOA accuracy with the old WWII standard of chrome.

Times are achanging, tho. Chrome will go away not because of the Hazmat, but because it's just easier to nitride a finished barrel with less rejects.

I believe that chrome lining holds up better to full auto use from some other things i have read, but for semi-auto i think i would rather use nitride due to accuracy potental

The two processes were tested by the military and CPL was found to hold up against throat erosion better under fully automatic fire. It seems the heat generated by firing affects the nitride barrels faster, as after all the process is a heat treat. Hardness values for all barrels go down significantly during the specified function testing due to heat. This testing was done many years ago, if any has been done since I haven't seen it.

For a civilian rifle I don't see any downside to nitriding, and the possibility of increased accuracy is indeed there. Even the best CPL barrels do have inconsistencies in the plating thickness, and as the barrel ages the chrome begins to crack microscopically and eventually starts to flake off, this is well documented even in the very best barrels. This can do nothing but affect accuracy. Of course it goes without saying that just because it's nitride doesn't automatically mean it's going to be more accurate, other factors could come into play there also.

Tirod, where do you get 2MOA as a mil-spec value?

I think nitride AR barrels are becoming very popular and would take over the market if it weren't for the folks that still want chrome-lined just because it is mil-spec.

PowerG said:

The two processes were tested by the military and CPL was found to hold up against throat erosion better under fully automatic fire.

Click to expand...

I was not aware of any small arms testing by the .mil to compare hard chrome lining vs. nitriding.

I've love a link!

It is my first choice of barrel material. bolt carrier too.

rbernie said:

I was not aware of any small arms testing by the .mil to compare hard chrome lining vs. nitriding.

I've love a link!

Click to expand...

I will see if I can find something. Someone posted a link on another forum I visit. will look after work

Well the chrome plating was really introduced for more than just anti-corrosion problems, the major complaint with the weapons first issued in Vietnam was a rash of failure to extract on the early, unlined weapons. Chrome lining of the chamber alleviated a lot of that problem. Additionally many rifles were inspected and found to have copper building up in the bores, and since chrome was known to reduce copper fouling they just started plating the whole thing. These early interviews also found that about half of the troops had used the forward assist.

rbernie, I have seen the study referenced online by other people but the only way I have seen it was in hard copy that a guy let me read years ago.

AFAIK, the original .mil analyses evaluated chrome lining vs. unlined/plain chrome moly barrels. I know that the .mil has recently looked at nitriding for field artillery barrels, but I've seen nothing in the .mil space that would provide a back-to-back between hard chrome lining and modern nitriding.

I found this one, but this is not the same one I read.

http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=AD0822736

There's nothing new about Nitride. It's been used for a long time in metal treatment. I bought my 1st Nitrided barrel 5-6 years ago. No more chrome barrels for me. I'm buying Nitride of stainless for my AR barrels.

Just a sample size of 1, but the one I have is the easiest cleaning barrel I've ever had.

Everready73 said:

I believe that chrome lining holds up better to full auto use from some other things i have read, but for semi-auto i think i would rather use nitride due to accuracy potental

Click to expand...

I've heard this also. Would be interested to research this a bit deeper to see what I can learn.

The only thing I can remember reading regarding longevity is something about battle field Las Vegas going through some (I think) H&K nitride barrels pretty quickly under a heavy firing schedule. That may be too small a sample size to cast blanket judgment.

I'm interested in the nitride process, though.

Tirod said:

They are only popular because hard chrome is difficult to apply in the US for environmental reasons.

They are popular because nitried is a surface hardening treatment, which phosphate or blueing does not do. More importantly, the rifling is the same as broached, with no additive plating. That means it's consistently more accurate if properly performed, and also can add a few fps to the velocity. Chrome has to be rifled oversized as the plating builds up the final dimension, and its also problematic about being concentric as the process is difficult to control. Barrels are routinely discarded - or salvaged in shorter lengths - because of bore obstructions due to uneven waviness in the bore. Tight spots can cause pressure spikes which can be dangerous - one early vendor of an alternate AR cartridge went out of business because of poor quality control by the plater.

Nitride avoids all that and makes for a better more concentric bore in large scale production, and is equally corrosion resistant. For the most part the Euro battle rifle companies switched to nitride decades ago when they went to cold hammer forged barrels. It was Colt who dragged their feet over it and the US Army saw no need to force the issue as they could provide milspec 2MOA accuracy with the old WWII standard of chrome.

Times are achanging, tho. Chrome will go away not because of the Hazmat, but because it's just easier to nitride a finished barrel with less rejects.

Click to expand...

Thanks for posting this, Tirod. Do you know off the top of your head which European military rifles use the nitride process?

My melonite 5.56 barrel is good but not great. It's a cheap barrel though so it may be more the quality than the finish. My new pistol barrel is nitrided but I haven't had the chance to run it through its paces yes.

Tirod said:

They are only popular because hard chrome is difficult to apply in the US for environmental reasons.

They are popular because nitried is a surface hardening treatment, which phosphate or blueing does not do. More importantly, the rifling is the same as broached, with no additive plating. That means it's consistently more accurate if properly performed, and also can add a few fps to the velocity. Chrome has to be rifled oversized as the plating builds up the final dimension, and its also problematic about being concentric as the process is difficult to control. Barrels are routinely discarded - or salvaged in shorter lengths - because of bore obstructions due to uneven waviness in the bore. Tight spots can cause pressure spikes which can be dangerous - one early vendor of an alternate AR cartridge went out of business because of poor quality control by the plater.

Nitride avoids all that and makes for a better more concentric bore in large scale production, and is equally corrosion resistant. For the most part the Euro battle rifle companies switched to nitride decades ago when they went to cold hammer forged barrels. It was Colt who dragged their feet over it and the US Army saw no need to force the issue as they could provide milspec 2MOA accuracy with the old WWII standard of chrome.

Times are achanging, tho. Chrome will go away not because of the Hazmat, but because it's just easier to nitride a finished barrel with less rejects.

Click to expand...

There are many reports that show, for military applications, namely full-auto, and extreme high pressure/temperature loadings, chrome plating is far superior to nitride. That is why the US still uses chromium plating in everything from small arms to 155mm howitzers....

(In the early 1990s, the US Army dropped nitride in favor of chrome plating in the M242 Bushmaster due to shorter that acceptable barrel life.)

Chrome will go away, only because current propellant flame temperatures are exceeding the ability of chromium to protect the barrel. It will not be replaced with nitride, at least in the US.

Oh, and one more thing...you can make a really good match grade barrel with a chrome plated bore. Find an L42A1, they all have chrome plated barrels and see how well they shoot. Or an M777 155mm howitzer, new, they are required to have a dispersion of no greater than 3/8 moa at 15 miles. They're chrome plated bores.

Nitride finished AR-15 barrels - Thoughts?

Click to expand...

At my LGS, an AR-15 with a chrome lined barrel is $1,100. An AR-15 with a nitrided barrel is $600.

I typically only recover about 60% of brass fired out of my ARs. That means that after about four reloadings, it's all been lost. Based on my exepcted use in retirement, I bought enough brass, bullets and powder to load about 5,000 rounds. Since all the writers in the Gun Press say that I should expect a nitrided barrel to last at least that long, that means barrel wear on my $600 AR will be a concern for my heirs.

So, I bought two of the $600 AR and gave one to my son.

"I typically only recover about 60% of brass fired out of my ARs. That means that after about four reloadings, it's all been lost. Based on my exepcted use in retirement, I bought enough brass, bullets and powder to load about 5,000 rounds."

Just FWIW: I have one of these brass catchers:
http://www.midwayusa.com/product/77...r-ar-15-picatinny-rail-mount-nylon-mesh-black
(additional mounts are $13)

Lake City once fired is what - 0.13 a round? If so 269 saved cases will pay for a catcher. 40% of 5000 is a lot more than 269 cases...

If I'm using it in one position - prone or off a bench, I leave the zipper open and cases just dribble out. If I'm shooting on the move then you have to empty it periodically - but that takes a lot less time than hunting brass.

IIRC the Garand was recommended to be chromed in the day, so that spec has been around a while.But the minimal cost was turned down. The Army added it back to the M16 when it was discovered that bare ordnance rifling tended to corrode and rust in a harsh wet climate. Duh. Budget mongers ignored it again to save a buck and it was a classic example of the wrong people handling the initial fielding when the subject matter experts were ignored and even shunted aside. Happens all the time in military and government procurement.

2 MOA has been the military standard specification for a long time, the process in testing for it was last refined in the 1950's and is still a subject of some debate in the internet. Milspec is to fire ten - 10 - rounds for a group using issue ammunition as provided by the ammo contractor and that group is measured for its deviation. All too many shooters like to shoot three or five and claim valid results, those discussions are notoriously defended in pages of posts all over the net.

The result of a 2MOA group is a ten inch group at 500m - which is a rare shot in battle - and certainly accurate enough considering the target area of an enemy soldier is 18 MOA - the height and width of the average human torso. It's the civilian shooter caught up in marketing who considers a smaller MOA to be needed - and for competition it may be, but for actual defense against other armed individuals, his skill under fire is more important.

I purchased an HK91 in the mid '70s for a deer rifle and those were CHF and nitrided barrels even then. One significant consideration of the M16 is that it MAY be fired full auto but consistently burning thru mags at a rapid rate is NOT doctrine nor was the weapon intended to be used that way all the time in battle. While a lot of folks like to say it's a better thing the reality is that no, the weapon doesn't get used that way very extensively at all, despite the hype. Rules of engagement have long set the firing rate at semi auto single fire simply to conserve ammo and get the soldier to slow down and aim - which is why we added red dot optics, too. As for full auto support fire the M60 and M249 is dedicated to that purpose and even then conserved to prevent drawing too much counterfire until it becomes obvious it's needed. The need for the M16 to resist full auto fire is largely overstated in practice. Don't forget that the Army switched away from full auto to three shot triggers for a long time - those guns never saw it.

So said my Infantry Officer instructors, who were all combat experienced NCO's been there and done that. And BTW, the red dots on military weapons are commonly 2MOA dots - or even larger. A smaller resolution wouldn't add nothing to the overall accuracy.

md7 said:

I've heard this also. Would be interested to research this a bit deeper to see what I can learn.

The only thing I can remember reading regarding longevity is something about battle field Las Vegas going through some (I think) H&K nitride barrels pretty quickly under a heavy firing schedule. That may be too small a sample size to cast blanket judgment.

I'm interested in the nitride process, though.



Thanks for posting this, Tirod. Do you know off the top of your head which European military rifles use the nitride process?

Click to expand...

There was a recent thread on M4c about that exact gun at Battlefield Vegas and it seems no one can figure out if the gun is even Nitrated or not. I guess even HK has given various answers.

http://www.dtic.mil/ndia/2002gun/waterfield.pdf That is a link for a study by Boeing that got similar results as the army one. The file for military testing is Technical Report ARCCD-TR-96002, 25-mm GUN SYSTEM WEAR ENGINEERING STUDY PROPOSAL 1A-0-8635 . I dont know how to access this though or where to find it